Female black-footed ferrets range in weight from 645 to 850 grams, while the weight of males ranges from 915 to 1,125grams. Mustela nigripes ranges in length from 380 to 600mm (head and body). In linear measurements, male black-footed ferrets are generally 10% larger than females. The fur of Mustela nigripes is yellowish-buff with pale underparts. The forehead, muzzle, and throat are white; while the feet are black. A black mask is observed around the eyes, which is well defined in young black-footed ferrets (Massicot 2000, Wilson & Ruff 1999, Nowak 1991, Hillman & Clark 1980).
Range mass: 645 to 1125 g.
Other Physical Features: endothermic ; bilateral symmetry
Average lifespan
Status: captivity: 12.0 years.
Black-footed ferrets can be found in the short or middle grass prairies and rolling hills of North America. Each ferret typically needs about 100-120 acres of space upon which to forage for food. They live within the abandoned burrows of prairie dogs and use these complex underground tunnels for shelter and hunting. A mother with a litter of three would need approximately 140 acres to survive (Massicot 2000, Nowak 1991).
Terrestrial Biomes: savanna or grassland
Historically, Mustela nigripes ranged throughout the interior regions of North America, from southern Canada to northern Mexico. Mustela nigripes is the only ferret that is native to North America. Today, Mustela nigripes exists in the wild in three locations, northeastern Montana, western South Dakota, and southeastern Wyoming. All three locations are sites where they have been reintroduced after the original populations were extirpated. Mustela nigripes populations also exist in seven zoos and breeding facilities (Massicot 2000, Wilson & Ruff 1999, Nowak 1991, Hillman & Clark 1980).
Biogeographic Regions: nearctic (Native )
Black-footed ferrets rely primarily on prairie dogs for food. However, they sometimes eat mice, ground squirrels, and other small animals. Normally, over 90% of a black-footed ferret's diet consists of prairie dogs, which are hunted and killed within their burrows. A black-footed ferret typically consumes between 50-70 grams of meat per day. It has been observed that black-footed ferrets only kill enough to eat, and caches of stored food are not usually found (Massicot 2000, Wilson & Ruff 1999, Nowak 1991, Hillman & Clark 1980).
Black-footed ferrets help control populations of prairie dogs, which are sometimes seen as pests because of their burrowing activities and because they as as reservoirs for zoonotic diseases such as bubonic plaque.
Black-footed ferrets are often seen as pests by ranchers. The tunnel systems that are used by ferrets and prairie dogs cause holes in the the earth in the grazing lands of cattle. Unfortunate livestock sometimes step into these holes and become lame, after which they must be destroyed.
Considered to be North America's rarest mammal. Black-footed ferrets have been heavily impacted by the extermination of prairie dogs. Ranchers poisoned prairie dogs because of destruction (tunneling and foraging) to rangelands. With the disappearance of prairie dogs, so too went black-footed ferrets. Numbers dropped to an astounding 31 in 1985, and by 1987 they were extinct in the wild. Of the original 100 million acres of black-footed ferret habitat, only 2 million acres remain. Many ferrets were also killed by a canine distemper epidemic that spread through the American grasslands.
Captive breeding and reintroduction programs are underway in several locations throughtout North America (Massicot 2000)
US Federal List: endangered
CITES: appendix i
IUCN Red List of Threatened Species: endangered
Perception Channels: tactile ; chemical
Females become sexually mature at the age of one year. The breeding season typically extends through March and April. The gestation period ranges from 35-45 days. Litters range from 1-6 young, with an average litter size of 3.5 young. Young remain in the burrow for about 42 days before coming aboveground. During the summer months of July and August females and their young stay together, in the fall they separate as the young ferrets reach their independence. Females ferrets have three pairs of mammae. Ferrets are sexually dimorphic, with males being larger than the female. During the mating season, females aggressively solicit males. Black-footed ferrets exhibit a phenomenon known as "delayed implantation," in which the fertilized egg does not start developing until conditions are appropriate for gestation (Massicot 2000, Wilson & Ruff 1999, Nowak 1991, Hillman & Clark 1980).
Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate); sexual
Average gestation period: 43 days.
Average number of offspring: 3.
Average age at sexual or reproductive maturity (male)
Sex: male: 365 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 365 days.
The spread of cattle ranching, farming and urban development in the 20th Century in the Great Plains has greatly stressed the North American prairie ecosystem. Ranchers asserted that grazing by prairie dogs deprived cattle of much otherwise available forage and began a campaign to eradicate this ‘pest’ species through strychnine poisoning (Jachowski and Lockhart, 2009). Black-footed ferrets, being a highly specialized predator on prairie dogs thus declined. In 1964 black-footed ferrets were believed to be extinct when a remnant population was found in South Dakota (Howard et al, 2002). Captive breeding of animals from this population was attempted at the Patuxent Wildlife Research Center in Maryland, but ultimately failed due to a flawed canine distemper vaccine and the disappearance of the wild population. In 1981the species was again believed extinct when a ranch dog near Meeteese,Wyoming brought home a dead ferret. From 1985 to 1987 the last 18 individuals were captured and brought into captivity, but only seven produced offspring. Since then the program has produced well over 6,000 animals. Over 3,000 captive-born ferrets have been released at 18 release sites ranging across the Great Plains and one in Mexico. Of these sites only two, Shirley Basin in Wyoming and Conata Basin in South Dakota, are showing a natural increase in population size. The ferret populations at the other sites may currently be too low to ensure survival into the future. Black-footed ferret prospects improve with larger habitat area and greater densities of prairie dogs. In addition diseases, such as plague or canine distemper, can wipe out ferrets locally. As of 2009 there are estimated to be over 800 black-footed ferrets in the wild, but only about 300 breeding adults (Jachowski and Lockhart, 2009).
Role of the Smithsonian in the Black-footed Ferret Recovery Program
In 1980 the black-footed ferret, Mustela nigripes, was feared extinct when an isolated remnant population was discovered Meeteese, Wyoming. In 1985 through 1987 the last 18 known individuals were captured and transported to a Wyoming Fish and Game facility for captive breeding. Only seven individuals successfully bred, from whom all living members of the species have descended. In 1988 the Smithsonian’s National Zoological Park became the first zoo to participate in the program when seven of the founders’ direct descendants were transferred to the Conservation Research Center in Front Royal, Virginia. In the mid-1980’s NZP researchers developed artificial insemination techniques on domestic ferrets and the Siberian polecat for use on black-footed ferrets. Techniques developed include evaluation of male testes and sperm, electroejaculation, cryopreservation of sperm and artificial insemination. From 1989 to 2009 566 ferrets were born at the CRC, 143 by artificial insemination. AI helped to insure against loss of the genetic diversity present in the founders. Positive results demonstrate that reproductive techniques are valuable for generating new knowledge of relevance to natural and assisted breeding and producing genetically valuable offspring useful for breeding stock and/or reintroduction (Hoard et al, 2002).
Historical habitats of the black-footed ferret included shortgrass prairie [41,49,65], mixed-grass prairie [27,49], desert grassland [51], shrub steppe [12,75], sagebrush steppe [7,11,12,20,30], mountain grassland, and semi-arid grassland [37].
Vegetation types occurring in 4 inventoried historic black-footed ferret habitats in Wyoming include: birdfoot sagebrush (Artemisia petadifida)/ western wheatgrass (Pascopyron smithii); big sagebrush (Artemisia tridentata); low sagebrush (Artemisia arbuscula)/mixed-grass (bottlebrush squirreltail (Elymus elymoides), western wheatgrass, and Sandberg bluegrass (Poa secunda)); Gardner's saltbush (Atriplex gardneri)/mixed-grass (Sandberg bluegrass and cheatgrass (Bromus tectorum)); thickspike wheatgrass (Elymus lanceolatus)-threadleaf sedge (Carex filifolia); mixed shrub (Artemisia spp.)/mixed-grass (thickspike wheatgrass and blue grama (Bouteloua gracilis)); and Gardner's saltbush [20].
Current habitat occupied by black-footed ferrets near Meeteetse, Wyoming, is wheatgrass (Agropyron spp.)-needlegrass (Stipa spp.) shrubsteppe (Artemisia spp.), dominated by bluebunch wheatgrass (Pseudoroegneria spicata), western wheatgrass, prairie junegrass (Koeleria macrantha), and big sagebrush [12,16,17,20,30]. Suitable habitat for black-footed ferrets near Meeteetse, Wyoming, may include meadows or saltbush (Atriplex spp.)/rabbitbrush (Chrysothamnus spp.) [5].
Information about plant communities at black-footed ferret reintroduction sites is sparse. In Aubrey Valley, Arizona, habitat is grassland dominated by blue grama, galleta grass (Hilaria jamesii), Indian ricegrass (Oryzopsis hymenoides), and other unspecified grasses [1].
Black-footed ferrets use prairie dog burrows for raising young, avoiding predators, and thermal cover [28,36,39]. Six black-footed ferret nests found near Mellette County, South Dakota, were lined with buffalo grass (Buchloe dactyloides), prairie threeawn (Aristita oligantha), sixweeks grass (Vulpia octoflora), and cheatgrass [65]. High densities of prairie dog burrows provide the greatest amount of cover for black-footed ferrets [28,39,61]. Black-tailed prairie dog colonies contain a greater burrow density per acre than white-tailed prairie dog colonies, and may be more suitable for the recovery of black-footed ferrets [39].
Type of prairie dog burrow may be important for occupancy by black-footed ferrets. Black-footed ferret litters near Meeteetse, Wyoming, were associated with mounded white-tailed prairie dog burrows, which are are less common than non-mounded burrows. Mounded burrows contain multiple entrances and probably have a deep and extensive burrow system that protects kits [28,39]. According to Richardson and others [61], however, black-footed ferrets used non-mounded prairie dog burrows (64%) more often than mounded burrows (30%) near Meeteetse, Wyoming.
The historical range of the black-footed ferret was closely correlated with, but not restricted to, the range of prairie dogs (Cynomys spp.). Its range extended from southern Alberta and southern Saskatchewan south to Texas, New Mexico, and Arizona [18,37,70].
As of 2007, the only known wild black-footed ferret population is located on approximately 6,000 acres (2,428 ha)in the western Big Horn Basin near Meeteetse, Wyoming [13,15,17,18,30,39,45,61]. It is possible that other wild black-footed ferret populations exist but remain undetected [12,37]. Since 1990, black-footed ferrets have been reintroduced to the following sites: Shirley Basin, Wyoming; UL Bend National Wildlife Refuge and Fort Belknap Reservation, Montana; Conata Basin/Badlands, Buffalo Gap National Grasslands, and the Cheyenne River Sioux Reservation in South Dakota; Aubrey Valley, Arizona [4,71]; Wolf Creek, Colorado; Coyote Basin, straddling Colorado and Utah [4]; and northern Chihuahua, Mexico [71]. Additional sites are being considered for the reintroduction of black-footed ferrets. NatureServe provides a distributional map for black-footed ferrets.
Up to 91% of black-footed ferret diet is composed of prairie dogs [18,34,36,65,66]. Most research indicates that prairie dogs are required prey for black-footed ferrets [6,10,13,16,26,36,53,53,64,67]. However, according to Owen and others [58], established colonies of prairie dogs may not be a prerequisite for successful reintroductions of black-footed ferrets. Anecdotal observations and 42% of examined fossil records indicated that any substantial colony of medium- to large-sized colonial ground squirrels, such as Richardson's ground squirrels (Spermophilus richardsonii), may provide a sufficient prey base and a source of burrows for black-footed ferrets. This suggests that black-footed ferrets and prairie dogs did not historically have an obligate predator-prey relationship [58].
Diet of black-footed ferrets varies depending on geographic location. In western Colorado, Utah, Wyoming, and Montana, black-footed ferrets historically associated with white-tailed prairie dogs and were required to find alternate prey when white-tailed prairie dogs hibernated for 4 months of the year [10,34]. In Wyoming, alternate prey items consumed during white-tailed prairie dog hibernation included voles (Microtus spp.) and mice (Peromyscus spp. and Mus spp.) found near streams. In South Dakota, black-footed ferrets associate with black-tailed prairie dogs. Because black-tailed prairie dogs do not hibernate, little seasonal change in black-footed ferret diet is necessary [10,61].
In Mellette County, South Dakota, black-tailed prairie dog remains occurred in 91% of 82 black-footed ferret scats. Mouse remains occurred in 26% of scats. Mouse remains could not be identified to species; however, deer mice, northern grasshopper mice (Onychomys leucogaster), and house mice (Mus musculus) were captured in snap-trap surveys [66]. Potential prey items included thirteen-lined ground squirrels (Spermophilus tridecemlineatus), plains pocket gophers (Geomys bursarius), mountain cottontails (Sylvilagus nuttallii), upland sandpipers (Bartramia longicauda), horned larks (Eremophila alpestris), and western meadowlarks (Sturnella neglecta) [36].
Based on 86 black-footed ferret scats found near Meeteetse, Wyoming, 87% of black-footed ferret diet was composed of white-tailed prairie dogs. Other food items included deer mice (Peromyscus maniculatus), sagebrush voles (Lemmiscus curtatus), meadow voles (Microtus pennsylvanicus), mountain cottontails , and white-tailed jackrabbits (Lepus townsendii) [7]. Water is obtained through consumption of prey [39].
One adult female black-footed ferret and her litter require approximately 474 to 1,421 black-tailed prairie dogs/year or 412 to 1,236 white-tailed prairie dogs/year for sustenance. These figures assume that each adult black-footed ferret occupies 1 prairie dog colony, each young black-footed ferret will disperse to a new colony when mature, and prairie dogs are the only prey species available. This dietary requirement would require protection of 91 to 235 acres (37-95 ha) of black-tailed prairie dog habitat or 413 to 877 acres (167-355 ha) of white-tailed prairie dog habitat for each female black-footed ferret with a litter [68].
As of 2007, no research has examined HABITAT RELATED FIRE EFFECTS for the black-footed ferret, and little is known about the effects of fire on prairie dogs. Despite the lack of information, some inferences may be possible. Because black-footed ferrets and prairie dogs occupy the same vegetation communities, HABITAT RELATED FIRE EFFECTS may be similar between the 2 species. If fire decreases or destroys prairie dog populations, associated black-footed ferret populations would most likely suffer from a loss in the prey base (see Food habits) and cover (see Cover Requirements).
An FEIS review on the black-tailed prairie dog suggests that fire may have positive or negative effects, depending on burn severity and season. Low-severity burns conducted during spring in non-drought years may stimulate the growth of black-tailed prairie dog colonies by reducing vegetational height and density at the colony periphery [24,25,35,40,42,43,44,55,57,60,69,73,76]. Prescribed burning and mechanical brush removal around the perimeter of black-tailed prairie dog colonies may encourage the expansion of black-tailed prairie dog colonies. High-severity burns have the potential of reducing habitat quality in a black-tailed prairie dog colony, at least in the short-term [67]. During the plant growing season, the absence of fire provides optimal conditions for black-tailed prairie dog colony growth [44]. For more information about HABITAT RELATED FIRE EFFECTS for the black-tailed prairie dog, see the FEIS review on the black-tailed prairie dog.
To increase the total area of prairie dog colonies in locations such as Grasslands National Park, range improvement via burning, seeding, grazing, or mowing tall vegetation is recommended before introducing black-footed ferrets [45]. Reintroductions of black-footed ferrets have been carried out at several locations (see Animal Distribution and Occurrence) but as of 2007, very little information has been published about habitat types at reintroduction sites, so HABITAT RELATED FIRE EFFECTS are unknown. If the habitat type is known at a black-footed ferret reintroduction site, refer to the table below for fire regime information.
The following table provides fire regime information on vegetation communities in which black-footed ferrets may occur. The selection of vegetation communities was based on vegetation communities inhabited by black-footed ferrets and prairie dogs, as well as limited historical data on black-footed ferret habitat. Black-footed ferrets may not currently occur in all of the habitat types listed, and some community types, especially those used rarely, may be omitted.
As of December 2006, 700 black-footed ferrets exist in the wild [71]. The national goal for a change in status of the black-footed ferret from endangered to threatened is to establish 10 wild, self-sustaining populations, each containing >30 breeding adults, and a total of 1,500 individuals spread over the widest possible geographic area [16,71]. Recovery efforts for black-footed ferrets include preserving prairie dog habitat [7,10,11,12,13,16,53,67], preserving remaining wild black-footed ferret populations, locating new black-footed ferret populations, and captive breeding and reintroduction into wild habitats [11,13,39,49].
Historically, large, nearly contiguous prairie dog colonies were interspersed with small, isolated colonies [28]. As a result of habitat fragmentation and eradication programs, prairie dog colonies are now smaller and more fragmented [7]. Prairie dog populations have recovered in many areas of the United States; however, the size and distribution of protected colonies are probably not sufficient to support large, stable populations of black-footed ferrets [53]. Clark [11] suggests that in rare species management, habitat should receive priority over scientific measurements.
To attract and maintain black-footed ferret populations, colony size and intercolony distance of prairie dogs are important [16,28]. Small peripheral prairie dog colonies that are associated with larger prairie dog colonies may be beneficial for occupancy by black-footed ferrets [30]. Hillman and others [38] and Forrest and others [28] recommend that each prairie dog colony within a complex of prairie dog colonies be >30 acres (12 ha), and ideally >124 acres (50 ha) in area. A preliminary estimate of 9,884 to 14,830 acres (4,000-6,000 ha) of prairie dog habitat is needed to support a minimum viable population of 100 black-footed ferrets [28,39]. Prairie dog complexes of this size are ideal but rare. Black-footed ferret populations can be maintained on smaller prairie dog complexes if genetic and population manipulations are conducted [28]. If prairie dog colonies are too small and spaced too far apart, black-footed ferrets will not be able to sustain themselves due to lack of food, burrows, and thermal cover. If prairie dog colonies are large and close together, it is easier for black-footed ferrets to move among prairie dog colonies [28,39]. In order to support black-footed ferret populations, most prairie dog colonies within a complex should occur within 4 miles (7 km) of each other, which is the distance that 1 black-footed ferret may travel in 1 night [28]. See Forrest and others [28] for a hypothetical prairie dog complex that may support black-footed ferrets.
White-tailed prairie dogs and black-tailed prairie dog colonies may offer slightly different advantages to black-footed ferrets. Some research suggests that black-footed ferrets may have a better chance of survival within black-tailed prairie dog colonies located in the Great Plains than those within white-tailed prairie dog colonies located in Montana, Wyoming, Utah, and Colorado [10,16]. Great Plains habitat supports dense colonies of black-tailed prairie dogs covering extensive areas, compared to white-tailed prairie dog habitat, where populations rarely exceed 100 individuals or several hectares in size. Burrow density is greater in Great Plains habitat, providing more cover for black-footed ferrets [39]. Because black-tailed prairie dogs do not hibernate, they provide a year-round food source for black-footed ferrets. The Great Plains also have more rainfall and more productive vegetation than white-tailed prairie dog habitat [10,16,39]. Other research suggests that black-footed ferrets have a better chance of survival within white-tailed prairie dog colonies because white-tailed prairie dogs occupy less-defined living areas, so the spread of sylvatic plague is inhibited [4,28].
A habitat suitability index model was designed by Houston and others [39] to locate reintroduction sites for black-footed ferrets. The model assumes that black-footed ferrets can meet year-round requirements in prairie dog colonies provided that prairie dog colonies are large enough, their burrows are numerous enough, and adequate prey are available for black-footed ferrets. The habitat suitability model should apply throughout the black-footed ferret's historic range [39]. A field habitat model was created by Miller and others [54] to compare prairie dog complexes with known black-footed ferret habitat. The model was created as an inexpensive method to search for black-footed ferret populations and to provide a rapid method for initial identification of prairie dog complexes to be considered for reintroduction sites. After sites are identified, they could be analyzed for reintroduction potential by Houston and others' [39] model [54].
Locating additional wild black-footed ferret populations may increase chances of recovery [16]. Trench-like formations are reliable indicators of black-footed ferret presence. Black-footed ferrets dig 2 to 10 foot (1-3 m) long trenches in prairie dog burrows to modify burrows and locate prey [36,49,61]. Prairie dogs destroy the trenches and plug new black-footed ferret burrows within 2 hours of sunrise. Black-footed ferret surveys must therefore be conducted before sunrise [49].
Captive breeding currently occurs at several zoos and the National Black-footed Ferret Conservation Center in Wyoming [71]. Captive breeding of black-footed ferrets allows population genetics, predation, and disease to be monitored and controlled [53]. Breeding black-footed ferrets in captivity and finding suitable sites for reintroduction are difficult [50]. Some problems associated with raising black-footed ferrets in captivity include abnormal physical features, lack of critical behavioral skills, and diseases [31]. For information about husbandry and veterinary care of black-footed ferrets, see Carpenter and Hillman [8]. Despite positive results with captive breeding, habitat destruction and disease in natural habitats will continue to be an issue [53].
Habitat management activities suggested for black-footed ferrets occupying white-tailed prairie dog colonies include: 1) recording white-tailed prairie dog emergence and breeding in late winter; 2) determining white-tailed prairie dog reproductive success in late spring; 3) mapping active and inactive white-tailed prairie dog colonies each fall; and 4) surveying alternate prey populations in late summer and early fall. For a detailed outline of annual monitoring and protection management needed for black-footed ferrets in Meeteetse, Wyoming, see Clark [13].
For information about current recovery efforts for the black-footed ferret, see the website for the National Black-Footed Ferret Recovery Program.
Domestic livestock grazing: According to Carrier and Czech [9], where wildlife occupy ecosystems used for livestock forage, grazing often alters these ecosystems, and native species often experience population declines as a result. Black-footed ferrets are a "priority species" in Arizona and New Mexico, meaning that they should receive greater consideration than non-priority wildlife species during development of management strategies related to livestock grazing [78].
Linder and others [48] recommend preserving prairie dog colonies for black-footed ferrets by obtaining easements from ranchers. A rancher could continue grazing livestock in a normal manner, but an easement could stipulate that prairie dogs not be eliminated or controlled using methods that are detrimental to black-footed ferrets. The rancher could be compensated for any increase in the size of prairie dog colonies. Miller and others [53] suggest an integrated management plan that satisfies ranchers and the conservation of grasslands. Federal money that is traditionally allocated to the prairie dog poisoning program could be used as a rebate for ranchers that manage livestock and preserve prairie dog colonies [53].
Other: Oil and natural gas exploration and extraction can have detrimental impacts on prairie dogs and black-footed ferrets. Seismic activity collapses prairie dog burrows. Other problems include potential leakages and spills, increased roads and fences, increased vehicle traffic and human presence, and an increased number of raptor perching sites on power poles. Traps set for coyotes, American mink (Mustela vison), and other animals may harm black-footed ferrets [13].
Native American tribes including the Crow, Blackfoot, Sioux, Cheyenne, and Pawnee used black-footed ferrets for religious rites and for food [10].
The black-footed ferret is apparently an obligate-dependent species (but see [58]), requiring white-tailed prairie dogs, black-tailed prairie dogs, or Gunnison's prairie dogs (Cynomys gunnisoni) for survival (see Food habits and Cover Requirements) [6,10,13,29,36,49,53,53,54,64].
The distribution, density, and potential for prairie dog colony expansion are important factors in identifying preferred habitat for black-footed ferrets [20,28]. Vegetation does not appear to have a direct influence on black-footed ferret distribution [20,28] and should not be considered an important factor when identifying suitable habitat for reintroduction [20].
Stand- and landscape-level habitat: As of 2007, the only wild population of black-footed ferrets occurs within 37 white-tailed prairie dog colonies in a grass/shrubsteppe vegetation community near Meeteetse, Wyoming (see Animal Distribution and Occurrence) [12,16,17,20,30]. Vegetation has been heavily grazed by domestic sheep, cattle, and horses for over 100 years [20]. Elevation ranges from 6,496 to 7,513 feet (1,980-2,290 m), and slopes do not exceed 30% [20,28]. Soils are shallow (1.6 feet (0.5 m)) [28], well-drained, and comprised of clay loams or clays derived from shale parent materials, which are ideal for prairie dog burrow construction. For more details on vegetation type and total percentage of cover, shrub density, topography, soils, climate, and geology near Meeteetse, Wyoming, see Collins and Lichvar [20] and Clark [13].
Black-footed ferrets cannot sustain their populations if prairie dog colonies are too small and the intercolony distance is too large [39]. In general, 1 black-footed ferret requires an area of 100 to 120 acres (40-49 ha) containing prairie dogs to survive [15,18,39]. To support 1 litter, approximately 99 to 148 acres (40-60 ha) of prairie dog habitat are required [18,28,30,38]; however, these numbers may vary depending on whether black-footed ferrets occupy white-tailed prairie dog colonies or black-tailed prairie dog colonies (see Food habits) [68].
In Mellette County, South Dakota, black-footed ferrets occupied black-tailed prairie dog colonies. Before the population disappeared, black-footed ferrets occupied 14 of 86 black-tailed prairie dog colonies, ranging from 20 to 35 acres (8-14 ha) in size. Four sites were located near creeks, 5 were in rolling grasslands, 4 were on flatlands, and 1 was located in a badland area [36].
Near Meeteetse, Wyoming, black-footed ferrets live within white-tailed prairie dog colonies, which range from 1.2 to 3,217.0 acres (0.5-1,302.0 ha) [28]. The mean distance between white-tailed prairie dog colonies is 0.57 miles (0.92 km) (range 0.08 to 2.30 miles (0.13-3.70 km)) [28,39,61]. The mean distance between white-tailed prairie dog colonies inhabited by black-footed ferrets is 3.4 miles (5.4 km) (range 0.6 to 6.9 miles (1.0-11.1 km)) [38].
Home range and density: Data are sparse on home range size for black-footed ferrets. Female black-footed ferrets have smaller home ranges than males. Home ranges of males may sometimes include the home ranges of several females [5,28,61]. Adult females usually occupy the same territory every year [53]. A female that was tracked for 4 months (December to March) occupied 39.5 acres (16.0 ha). Her territory was overlapped by a resident male that occupied 337.5 acres (136.6 ha) during the same period [28].
The average density of black-footed ferrets near Meeteetse, Wyoming, is estimated at 1 black-footed ferret /99 to148 acres (40-60 ha). As of 1985, 40 to 60 black-footed ferrets occupied a total of 6,178 to 7,413 acres (2,500-3,000 ha) of white-tailed prairie dog habitat [28,29,39].
Movement: From 1982 to 1984, the average year-round movement of 15 black-footed ferrets between white-tailed prairie dog colonies was 1.6 miles/night (2.5 km) ((SD 1.1 miles (1.7 km)) [28]. Movement of black-footed ferrets between prairie dog colonies is influenced by factors including breeding activity, season, sex, intraspecific territoriality, prey density, and expansion of home ranges with declining population density [5,12,28,30,61]. Movements of black-footed ferrets have been shown to increase during the breeding season [12,28]; however, snow-tracking from December to March over a 4-year period near Meeteetse, Wyoming revealed that factors other than breeding were responsible for movement distances [61]. One black-footed ferret (sex not given) near Meeteetse, Wyoming, traveled an average of 331 feet (101 m)/night prior to the breeding season and 19,370 feet (5,905 m)/night during the breeding season [12].
Temperature is positively correlated with distance of black-footed ferret movement [61]. Snow-tracking from December to March over a 4-year period near Meeteetse, Wyoming, revealed that movement distances were shortest during winter and longest between February and April, when black-footed ferrets were breeding and white-tailed prairie dogs emerged from hibernation. Nightly movement distance of 170 black-footed ferrets averaged 0.87 miles (1.41 km) (range 0.001 to 6.91 miles (0.002-11.12 km)). Nightly activity areas of black-footed ferrets ranged from 1.0 to 337.5 acres (0.4-136.6 ha), and were larger from February to March (x=110.2 acres (44.6 ha)) than from December to January (x=33.6 acres (13.6 ha)) [61]. Adult females establish activity areas based on access to food for rearing young. Males establish activity areas to maximize access to females, resulting in larger activity areas than those of females [61].
Prey density may account for movement distances. Black-footed ferrets may travel up to 11 miles (17 km) to seek prey, suggesting that they will interchange freely among white-tailed prairie dog colonies that are less than 11 miles apart [28]. In areas of high prey density, black-footed ferret movements were nonlinear in character, probably to avoid predators [61]. From December to March over a 4-year study period, black-footed ferrets investigated 68 white-tailed prairie dog holes per 1 mile (2 km) of travel/night. Distance traveled between white-tailed prairie dog burrows from December to March averaged 74.2 feet (22.6 m) (n=149 track routes)[61].
Population trends: Black-footed ferrets experience large population fluctuations that are determined by population density, prey availability, predation, and disease [30]. Populations are highest after kits first appear aboveground in summer [29,30]. A conservative minimum viable population size estimate for black-footed ferrets based on genetic considerations is 100 breeding individuals/12,360 acres (5,000 ha) [12,28,39] (see Management Considerations).
LIFE HISTORY:
Little is known about the life history, behavior, or ecology of black-footed ferrets due to their nocturnal and subterranean habits [29,37,49,53,61] and their rarity. Reproductive physiology of the black-footed ferret is similar to that of the European polecat (Mustela putorius) and the steppe polecat (Mustela eversmanii) [53].
Mating: Black-footed ferrets are probably polygynous, based on data collected from home range sizes, skewed sex ratios, and sexual dimorphism [5,28,30,61]. Mating occurs in February and March [15,61]. Unlike other mustelids, black-footed ferrets are habitat specialists and have low reproductive rates [8,30]. The sex ratio of adults near Meeteetse, Wyoming, was 1 male:2.2 females (n=128) [30].
Reproductive success: Reproductive success in the wild is unknown.
Gestation period and litter size: In captivity, gestation of black-footed ferrets lasts 42 to 45 days [8]. Litter size ranges from 1 to 5 kits [10,29,48]. In Mellette County, South Dakota, mean litter size was 3.4 kits (n=11) [48]. Near Meeteetse, Wyoming, mean litter size over a 4-year period was 3.3 kits (n=68) [30]. Kits are born in May and June [71] in prairie dog burrows (see Cover Requirements) [39].
Development: Kits are altricial and are raised by their mother for several months after birth [41,63]. Kits first emerge above ground in July, at 6 weeks old [30,36,71]. They are then separated into individual prairie dog burrows around their mother's burrow [36,53,63]. Kits reach adult weight and become independent several months following birth, from late August to October [5,30,36,63]. Sexual maturity occurs at 1 year old [36].
Social organization: Black-footed ferrets are solitary, except when breeding or raising litters [28,39,53,61,62].
Habits: Black-footed ferrets are primarily nocturnal [10,31,39,41]. They are most active above ground from dusk to midnight and 4 AM to midmorning [36]. Aboveground activity is greatest during late summer and early fall when juveniles become independent [5,36]. Climate generally does not limit black-footed ferret activity [36,61], but they may remain inactive inside burrows for up to 6 days at a time during winter [15].
Dispersal: Intercolony dispersal of juvenile black-footed ferrets occurs several months after birth, from early September to early November. Dispersal distances may be short or long. Near Meeteetse, Wyoming, 9 juvenile males and 3 juvenile females dispersed 1 to 4 miles (1-7 km) following litter breakup. Four juvenile females dispersed a short distance (<0.2 miles (0.3 km)) but remained on their natal area. One juvenile female remained on her mother's home range and reared a litter the following year in her mother's absence [30].
Mortality: Primary causes of mortality include habitat loss, human-introduced diseases, and indirect poisoning from prairie dog control [10,14,15,36,41,50,63,71]. Annual mortality of juvenile and adult black-footed ferrets over a 4-year period ranged from 59% to 83% (n=128) near Meeteetse, Wyoming [30]. During fall and winter, 50% to 70% of juveniles and older animals "disappear" due to emigration or death [28,29,30]. Average lifespan in the wild is probably only 1 year [29] but may be up to 5 years [4,41]. Males have higher rates of mortality than females due to longer dispersal distances when they are most vulnerable to predators [30].
Given an obligate-dependence of black-footed ferrets on prairie dogs (but see [58]), black-footed ferrets are extremely vulnerable to prairie dog habitat loss (see Preferred Habitat and Management Considerations) [53,54]. Habitat loss results from agriculture, livestock use, and other development [56,71].
Black-footed ferrets are susceptible to numerous diseases. They are fatally susceptible to canine distemper (Morbilivirus) [8,30,37], introduced by striped skunks (Mephitis mephitis), common raccoons (Procyon lotor), red foxes (Vulpes vulpes), coyotes (Canis latrans) [15,16], and American badgers (Taxidea taxus) [15]. A short-term vaccine for canine distemper is available for captive black-footed ferrets, but no protection is available for young born in the wild [8,31]. Other diseases that black-footed ferrets are susceptible to include rabies, tularemia, and human influenza [41]. Sylvatic plague (Yersinia pestis) probably does not directly affect black-footed ferrets, but epidemics in prairie dog towns may completely destroy the black-footed ferrets' prey base (see Food habits) [19,30,41,50,63].
Ar pudask pavioù du (Mustela nigripes) zo ur c'higdebrer bihan a vev en Amerika an Norzh. Kar eo da pudask ar stepennoù.
Aet e oa da get e Kanada e 1937 hag e 1980 ne chome nemet ur boblañs ouez, dizoloet dre zegouezh e Wyoming. Paket e oa bet evit he gwareziñ kent na yafe da get. Un nebeud loened maget er gwarezva a oa bet lezet da vont goude-se met ar poblañsoù a chom bihan.
War-dro 45 cm eo e hirder hag 1 kg e bouez. Ul lost blevek 15 cm en deus ivez. Evel izili all e gerentiad eo moan ha hir e gorf ha berr e bavioù. Gwenn eo e vlevenn dre vras nemet e bavioù, e c'houzoug ha penn e lost hag a zo du. Ne gemm ket e liv diouzh an amzer.
Ur c'higdebrer oberiant diouzh an noz eo. Chas-pradenn a zebront dreist-holl ha ne c'hellont ket treuzvevañ hepto. Kuzhat a reont en un douarenn diouzh an deiz.
Distruj ar pradennoù, digresk ar poblañsoù chas-pradenn hag efedoù drastus kleñvedoù evel kinomoz pe bosenn ar c'hoadegoù (heñvel a-walc'h ouzh ar vosenn) a voe abegoù diskar poblañs ar pudasked pavioù du. Aet e oant kazi da get e-pad an XIXvet hag an XXvet kantved.
Anavezet e voent evel ur spesad distag e 1851 hepken, goude embannadur ul levr gant John James Audubon ha John Bachman.
E 1981 e tizoljod ur boblañs vihan 130 hinienn enni e-kichen Meeteetse, Wyoming. War zigresk ez eas abred abalamour d'ar c'hleñved hag e 1986 e tapas ar Wyoming Game and Fish Department an 18 loen a chome d'o gwareziñ. D'ar poent-se na oa nemet 50 pudask pavioù du ken er bed.
E 1991 e teraoujod da lezel pudasked pavioù du da vont en natur en dro. Krediñ a reer e oa war-dro 400 penn er bed.
Ar pudask pavioù du (Mustela nigripes) zo ur c'higdebrer bihan a vev en Amerika an Norzh. Kar eo da pudask ar stepennoù.
Aet e oa da get e Kanada e 1937 hag e 1980 ne chome nemet ur boblañs ouez, dizoloet dre zegouezh e Wyoming. Paket e oa bet evit he gwareziñ kent na yafe da get. Un nebeud loened maget er gwarezva a oa bet lezet da vont goude-se met ar poblañsoù a chom bihan.
El turó de peus negres (Mustela nigripes) és un mamífer extint en estat salvatge que està sent reintroduït al centre dels Estats Units. Antigament vivia arreu de les praderies americanes. El 1991 se'n començaren a alliberar exemplars de manera controlada i des d'aleshores les poblacions n'han augmentat bastant. L'espècie estigué durant molt de temps al caire de l'extinció però, el 1981, uns investigadors en capturaren l'última població coneguda en un intent reeixit de salvar l'espècie.
El turó de peus negres (Mustela nigripes) és un mamífer extint en estat salvatge que està sent reintroduït al centre dels Estats Units. Antigament vivia arreu de les praderies americanes. El 1991 se'n començaren a alliberar exemplars de manera controlada i des d'aleshores les poblacions n'han augmentat bastant. L'espècie estigué durant molt de temps al caire de l'extinció però, el 1981, uns investigadors en capturaren l'última població coneguda en un intent reeixit de salvar l'espècie.
Tchoř černonohý (Mustela nigripes) je ohrožená šelma z čeledi lasicovitých. Jeho domovem byly severoamerické Velké pláně.
Je považován za nejvzácnějšího severoamerického savce, v roce 1985 přežívalo jen 31 jedinců (někdy se uvádí pouhých 18). Stalo se tak v důsledku hubení psounů, kteří jsou jeho hlavní potravou, a jejichž nory mu slouží jako úkryt. Poslední žijící zvířata byla odchycena a chována v zajetí. Roku 1994 bylo v Národním parku Badlands vypuštěno 36 jedinců, v následujících letech bylo několik stovek tchořů přemístěno do psouních kolonií nacházejících se na chráněných územích. V roce 2007 existovalo v přírodě 650 kusů těchto tchořů.
V současnosti žijí v sedmi zoologických zahradách, v severovýchodní Montaně, západní Jižní Dakotě a v jihovýchodním Wyomingu. Přežití tchoře černonohého je předmětem diskusí mezi ochranáři a zemědělci , jak by měly být využity a spravovány severoamerické prérie. Ekosystém prérií je velmi citlivý a vyvážené soužití predátorů s kořistí velmi křehké. Populace predátorů kolísá v závislosti na podnebí i místních podmínkách a pochopitelně i podle osudových zásahů člověka. Tchoř černonohý stál na pokraji vyhynutí několikrát. Jeho existence je závislá na dostatku psounů prériových, kteří tvoří 90 % jeho jídelníčku. Pokles početnosti psounů je důsledkem pronásledování ze strany chovatelů dobytka, kteří je tradičně považují za nebezpečná zvířata, jež škodí na pastvinách. Nesčetné vyhlazovací akce namířené proti psounům vedly nevyhnutelně také k poklesu počtu tchořů, kteří na obdělávaných polích a pastvinách nenacházejí dostatek jiné potravy. Původně se tchoři vyskytovali od Kanady po Texas a Arizonu, ale dnes jim zůstala jen 2 % původního biotopu, jež jsou navíc rozdrobena na nepatrné plochy, oddělené obrovskými lány polí a městy. Pro tchoře je jejich překonávání při hledání potravy příliš nebezpečné nebo přímo nemožné. Kromě toho tchoři doplatili na lov a trávení. V šedesátých letech 20. století byl považován takřka za vyhubeného, a byl zahájen program chovu a rozmnožení v lidské péči a pozdějšího navrácení do přírody. První skupiny zvířat uhynuly v důsledku psinky, kterou přenášejí domácí zvířata. Následoval další odchyt a odchov 50 tchořů, jež byli vráceni k volně žijící populaci. Ta stále přežívá v sedmi chráněných oblastech. Tchoř černonohý je noční samotář. Samec se od samice liší hlavně větší velikostí. Dospělí jedinci dosahují průměrné délky 60–63 cm i s ocasem.
Obrázky, zvuky či videa k tématu tchoř černonohý ve Wikimedia Commons
Tchoř černonohý (Mustela nigripes) je ohrožená šelma z čeledi lasicovitých. Jeho domovem byly severoamerické Velké pláně.
Je považován za nejvzácnějšího severoamerického savce, v roce 1985 přežívalo jen 31 jedinců (někdy se uvádí pouhých 18). Stalo se tak v důsledku hubení psounů, kteří jsou jeho hlavní potravou, a jejichž nory mu slouží jako úkryt. Poslední žijící zvířata byla odchycena a chována v zajetí. Roku 1994 bylo v Národním parku Badlands vypuštěno 36 jedinců, v následujících letech bylo několik stovek tchořů přemístěno do psouních kolonií nacházejících se na chráněných územích. V roce 2007 existovalo v přírodě 650 kusů těchto tchořů.
V současnosti žijí v sedmi zoologických zahradách, v severovýchodní Montaně, západní Jižní Dakotě a v jihovýchodním Wyomingu. Přežití tchoře černonohého je předmětem diskusí mezi ochranáři a zemědělci , jak by měly být využity a spravovány severoamerické prérie. Ekosystém prérií je velmi citlivý a vyvážené soužití predátorů s kořistí velmi křehké. Populace predátorů kolísá v závislosti na podnebí i místních podmínkách a pochopitelně i podle osudových zásahů člověka. Tchoř černonohý stál na pokraji vyhynutí několikrát. Jeho existence je závislá na dostatku psounů prériových, kteří tvoří 90 % jeho jídelníčku. Pokles početnosti psounů je důsledkem pronásledování ze strany chovatelů dobytka, kteří je tradičně považují za nebezpečná zvířata, jež škodí na pastvinách. Nesčetné vyhlazovací akce namířené proti psounům vedly nevyhnutelně také k poklesu počtu tchořů, kteří na obdělávaných polích a pastvinách nenacházejí dostatek jiné potravy. Původně se tchoři vyskytovali od Kanady po Texas a Arizonu, ale dnes jim zůstala jen 2 % původního biotopu, jež jsou navíc rozdrobena na nepatrné plochy, oddělené obrovskými lány polí a městy. Pro tchoře je jejich překonávání při hledání potravy příliš nebezpečné nebo přímo nemožné. Kromě toho tchoři doplatili na lov a trávení. V šedesátých letech 20. století byl považován takřka za vyhubeného, a byl zahájen program chovu a rozmnožení v lidské péči a pozdějšího navrácení do přírody. První skupiny zvířat uhynuly v důsledku psinky, kterou přenášejí domácí zvířata. Následoval další odchyt a odchov 50 tchořů, jež byli vráceni k volně žijící populaci. Ta stále přežívá v sedmi chráněných oblastech. Tchoř černonohý je noční samotář. Samec se od samice liší hlavně větší velikostí. Dospělí jedinci dosahují průměrné délky 60–63 cm i s ocasem.
Den sortfodede ilder (Mustela nigripes) er et dyr i mårfamilien under rovdyrene. Den blev for nylig[2] udryddet i naturen, men er gradvist ved at blive genindført gennem opdræt i fangenskabs-programmer.[3]
Den sortfodede ilder (Mustela nigripes) er et dyr i mårfamilien under rovdyrene. Den blev for nylig udryddet i naturen, men er gradvist ved at blive genindført gennem opdræt i fangenskabs-programmer.
Der Schwarzfußiltis (Mustela nigripes) ist eine in Nordamerika verbreitete Raubtierart aus der Untergattung der Iltisse innerhalb der Familie der Marder (Mustelidae). Schwarzfußiltisse nutzen als Beutetier überwiegend Präriehunde. Die Ausrottung der als Landwirtschaftsschädlinge eingeordneten Präriehunde in vielen Gebieten Nordamerikas führte entsprechend zu einem Bestandszusammenbruch beim Schwarzfußiltis. 1996 wurde der Schwarzfußiltis von der IUCN Red List als in der freien Wildbahn ausgestorben gelistet. Dank Nachzuchtprogrammen konnte das Überleben dieser Art gesichert werden. Der heute in freier Wildbahn lebende Bestand geht auf in Gefangenschaft gezüchtete Individuen zurück.
Schwarzfußilitsse haben wie alle Iltisse einen langgestreckten, schlanken Körper mit kurzen Gliedmaßen und relativ kurzem Schwanz. Ihr Fell ist überwiegend gelbbraun gefärbt, der Kopf ist weiß und ist um die Augen mit einer dunklen, maskenartigen Gesichtszeichnung versehen. Ebenfalls schwarz sind die Beine und der hinterste Teil des Schwanzes. Diese Tiere erreichen eine Kopfrumpflänge von 38 bis 50 Zentimeter, der Schwanz wird rund 11 bis 15 Zentimeter lang und ihr Gewicht beträgt 0,7 bis 1,1 Kilogramm. Männchen werden rund 10 % schwerer als Weibchen.
Ursprünglich waren Schwarzfußiltisse in der Prärie-Region des mittleren Nordamerikas beheimatet. Ihr Verbreitungsgebiet erstreckte sich von Alberta und Saskatchewan bis Arizona und Texas. Heute gibt es mehrere kleine Populationen in Montana, South Dakota, Wyoming und Arizona, die alle auf Wiederansiedlungsprogramme zurückzuführen sind. Ihr Lebensraum sind Grasländer.
Die Lebensweise der Schwarzfußiltisse ist eng an Präriehunde gekoppelt. Sie benutzen deren Baue als Ruheplätze und Jagdreviere. Sie gehen bei Dämmerung oder Nacht auf die Jagd und ziehen sich tagsüber in ihre Baue, die meist umgebaute Präriehundbauten sind, zurück. Sie leben einzelgängerisch und verteidigen ihr Revier vehement gegen Artgenossen.
Präriehunde machen dementsprechend auch 90 % ihrer Nahrung aus, in geringem Ausmaß verzehren sie auch andere Kleinsäuger wie andere Erdhörnchen und Mäuse.
Die Paarungszeit liegt in den Monaten März und April, nach rund 42- bis 45-tägiger Tragzeit bringt das Weibchen im Mai oder Juni ein bis sechs (durchschnittlich drei) Jungtiere zur Welt. Im Herbst trennen sie sich von ihrer Mutter, die Geschlechtsreife tritt mit rund einem Jahr ein. Die Lebenserwartung von Tieren in menschlicher Obhut betrug bis zu zwölf Jahre.
Bis Anfang des 20. Jahrhunderts waren Schwarzfußiltisse weit verbreitet. Ihre Zahl wird für den Beginn des 20. Jahrhunderts auf fünf bis sechs Millionen geschätzt.[1] Zu jenem Zeitpunkt waren Präriehunde, die ihre wichtigste Nahrungsquelle darstellen, in den Prärien Nordamerikas noch weit verbreitet und ihre Bestandszahl sehr hoch. Mit der großflächigen Ausrottung der Präriehunde, die als Landwirtschaftsschädlinge betrachtet wurden, setzte auch ein sehr starker und schneller Bestandsrückgäng bei den Schwarzfußiltissen ein. Im US-Bundesstaat Oklahoma wurden Schwarzfußiltisse bereits 1932 nicht mehr beobachtet, in Nebraska waren sie 1949 ausgestorben.
Nachzuchtbemühungen setzten bereits gegen Ende der 1960er Jahre ein. 1964 wurde in dem im Westen von South Dakota gelegenen Mellette County eine kleine Population von Schwarzfußiltissen entdeckt. Sechs der Tiere wurden 1971 gefangen, um mit einem Nachzuchtprogramm zu beginnen.[2] Sie starben jedoch nach unerwarteten Komplikationen durch eine Staupe-Impfung. Mit weiteren Fängen aus dieser Population versuchte man jedoch erneut, ein Zuchtprogramm zu begründen. Die wildlebende Population in South Dakota erlosch 1975, das letzte Individuum aus dem in Gefangenschaft gehaltenen Teil dieser Population starb 1979.[3] Damit galt die Art als ausgestorben.
Der Schwarzfußiltis wird als Beispiel für den Romeo-Irrtum genannt.[4] Eine Kette von Zufällen führte zur Entdeckung einer bis dahin unbekannten Kolonie von Präriehunden in Wyoming, in der auch Schwarzfußiltisse lebten. Ein Hofhund hatte ein wieselähnliches Tier getötet, der Besitzer des Hundes brachte den Kadaver zu einem Taxidermisten, um den Kadaver ausstopfen zu lassen. Dem Taxidermisten war die Art nicht bekannt, was ihn veranlasste, einen Mitarbeiter des Naturschutzes anzurufen. Noch im Oktober dieses Jahres gelang es zwei Biologen einen lebenden Schwarzfußiltis in dieser Region zu fangen. Eine intensive Suche führte dann zur Entdeckung einer großen Präriehundkolonie, in der nach Zählung im Jahre 1982 nicht weniger als 129 Schwarzfußiltisse lebten. Im Frühjahr 1985 war der Bestand jedoch auf 52 Iltisse gefallen und betrug im Herbst unter anderem durch den Ausbruch einer Staupe-Epidemie nur noch 16 Individuen.[5] Man entschied sich erneut für ein Nachzuchtprogramm und begann mit dem Fang von Individuen im Verlauf des Jahres 1985. Der heutige Bestand geht auf 18 Individuen zurück, die in dieser Kolonie gefangen wurden.
Das Nachzuchtprogramm war erfolgreich, und im Jahr 1991 wurden erstmals wieder Schwarzfußiltisse ausgewildert. Bis zum Jahr 2001 gab es Auswilderungen im Charles M. Russel National Wildlife Refuge und Bellnap Indian Reservation (beide im Osten von Montana), im Badlands National Park und Buffalo Gap National Graslands (beide im West von South Dakota), im Osten von Wyoming (Shirley Basin), im Nordwesten von Arizona (Aubrey Valley) und im Grenzland von Utah und Colorado (Coyoty Basin) sowie in Janus im Norden des mexikanischen Bundesstaates Chihuahua, wo die derzeit größte Präriehundkolonie besteht.[6] Nicht jede dieser Wiederansiedelungen war erfolgreich; sowohl in Wyoming als auch im Gebiet von Colorado/Utah starben die ausgewilderten Tiere sämtlich an Krankheiten. Als besonders erfolgreich gelten die beiden Auswilderungen in South Dakota, wo von 1994 bis zum Jahr 2001 insgesamt 225 Jungtiere geboren wurden und der dort lebende Bestand auf 200 Individuen geschätzt wird.[7] Die Gesamtpopulation wurde im Jahr 2005 wieder auf 500 Exemplare geschätzt.
Im Jahr 2020 schlossen sich Mitarbeiter des Zoos von San Diego, der Naturschutzorganisation Revive & Restore, der ViaGen Pets and Equine Company und des U.S. Fish and Wildlife Service für ein Klonprojekt zusammen. Hierfür wurde die DNA eines Mitte der 1980er Jahre gestorbenen Weibchen namens Willa ausgewählt, das keine lebenden Nachkommen hinterlassen hatte. Am 10. Dezember 2020 gelang die erste erfolgreiche Geburt eines Klons, ein Weibchen names Elizabeth Ann. Die Wissenschaftler hoffen durch diese Maßnahmen den Genpool der Iltisse zu vergrößen und damit gegen die silvatische Pest widerstandsfähigere Tiere zu züchten. Experten schätzen, dass das Genom dieses Weibchens dreimal so viel genetische Vielfalt enthält wie das der noch existierenden Schwarzfußiltisse.[8][9]
Der Schwarzfußiltis (Mustela nigripes) ist eine in Nordamerika verbreitete Raubtierart aus der Untergattung der Iltisse innerhalb der Familie der Marder (Mustelidae). Schwarzfußiltisse nutzen als Beutetier überwiegend Präriehunde. Die Ausrottung der als Landwirtschaftsschädlinge eingeordneten Präriehunde in vielen Gebieten Nordamerikas führte entsprechend zu einem Bestandszusammenbruch beim Schwarzfußiltis. 1996 wurde der Schwarzfußiltis von der IUCN Red List als in der freien Wildbahn ausgestorben gelistet. Dank Nachzuchtprogrammen konnte das Überleben dieser Art gesichert werden. Der heute in freier Wildbahn lebende Bestand geht auf in Gefangenschaft gezüchtete Individuen zurück.
De swartpoatmurd (Latynske namme: Mustela nigripes) is in sûchdieresoarte dy't ta it skift fan 'e rôfdieren, de famylje fan 'e martereftigen (Mustelidae) en it skaai fan 'e lytse marters (Mustela) heart. Hy is lânseigen op 'e prêrjes fan Noard-Amearika, dêr't er foar 91% libbet fan prêrjehûnen. Syn IUCN-status is "bedrige", mei't er in hoartsje op 'e râne fan it útstjerren balansearre hat. Oars as oare martereftigen is de swartpoatmurd in habitatspesjalist, dy't him yn 'e regel stadich fuortplantet.
De swartpoatmurd liket tige op 'e Jeropeeske murd, mei as wichtichste ferskil dat er wat mânsker is en in grutter kleurkontrast fertoant tusken syn dûnkere poaten en syn ljochte liif. In folwoeksen mantsje is trochinoar 50-53,3 sm lang (kop-romp), mei in sturt fan likernôch 12 sm en in gewicht dat útinoar rinne kin fan 650 g oant 1,4 kg. De wyfkes binne trochinoar 10% lytser as mantsjes. Yn finzenskip bliuwe se frjemd genôch lytser as yn it wyld, hoewol't útsette eksimplaren rillegau in normale grutte en gewicht berikke. It binne nachtdieren, dy't solitêr libje, útsein as it om wyfkes mei in nêst jongen giet. Se libje ornaris yn ferlitten (of leechfretten) prêrjehûnehoalen.
Swartpoatmurden waarden foar it earst troch de Westerske wittenskip ûntdutsen yn 1851. Fan 'e ein fan 'e njoggentjinde iuw ôf rekke it mei de soarte slim yn it neigean, fanwegen ôfnimmende oantallen prêrjehûnen en in epidemy fan sylvatyske pest. De soarte waard yn 1979 foar útstoarn ferklearre, oant yn 1981 de hûn fan in Lucille Hogg út Meeteetse, yn 'e Amerikaanske steat Wyoming, har in deade swartpoatmurd brocht.
Dy restpopulaasje fan in stik as tweintich, tritich eksimplaren libbe dêr oant de soarte yn 1987 yn it wyld útstoar. Tsjin dy tiid wie der lykwols yn finzenskip in fokprogramma opset troch de Amerikaanske Fiskerij- en Faunatsjinst (USFWS), dat tusken 1991 en 2008 resultearre hat yn 'e reyntroduksje yn it wyld fan swartpoatmurden yn acht westlike Amerikaanske steaten en teffens yn noardlik Meksiko. Hjoed de dei binne der mear as 1.000 folwoeksen, yn it wyld berne eksimplaren yn 18 ûnderskate populaasjes, wêrfan't 4 no folslein selsrêdsum binne: twa yn Súd-Dakota en ien elk yn Arizona en Wyoming. Fanwegen syn noch behindige oantal en beheinde populaasjes stiet de swartpoatmurd lykwols noch altyd te boek as bedrige.
De swartpoatmurd (Latynske namme: Mustela nigripes) is in sûchdieresoarte dy't ta it skift fan 'e rôfdieren, de famylje fan 'e martereftigen (Mustelidae) en it skaai fan 'e lytse marters (Mustela) heart. Hy is lânseigen op 'e prêrjes fan Noard-Amearika, dêr't er foar 91% libbet fan prêrjehûnen. Syn IUCN-status is "bedrige", mei't er in hoartsje op 'e râne fan it útstjerren balansearre hat. Oars as oare martereftigen is de swartpoatmurd in habitatspesjalist, dy't him yn 'e regel stadich fuortplantet.
The black-footed ferret (Mustela nigripes), also known as the American polecat[2] or prairie dog hunter,[3] is a species of mustelid native to central North America.
The black-footed ferret is roughly the size of a mink and is similar in appearance to the European polecat and the Asian steppe polecat. It is largely nocturnal and solitary, except when breeding or raising litters.[4][5] Up to 90% of its diet is composed of prairie dogs.[6][7]
The species declined throughout the 20th century, primarily as a result of decreases in prairie dog populations and sylvatic plague. It was declared extinct in 1979, but a residual wild population was discovered in Meeteetse, Wyoming in 1981.[8] A captive-breeding program launched by the United States Fish and Wildlife Service resulted in its reintroduction into eight western US states, Canada, and Mexico from 1991 to 2009. As of 2015, over 200 mature individuals are in the wild across 18 populations, with four self-sustaining populations in South Dakota, Arizona, and Wyoming.[1][9] It was first listed as "endangered" in 1982, then listed as "extinct in the wild" in 1996 before being upgraded back to "endangered" in the IUCN Red List in 2008.[1] In February 2021, the first successful clone of a black-footed ferret, a female named Elizabeth Ann, was introduced to the public.[10]
Like its close relative, the Asian steppe polecat (with which it was once thought to be conspecific), the black-footed ferret represents a more progressive form than the European polecat in the direction of carnivory.[2] The black-footed ferret's most likely ancestor was Mustela stromeri (from which the European and steppe polecats are also derived), which originated in Europe during the Middle Pleistocene.[11] Molecular evidence indicates that the steppe polecat and black-footed ferret diverged from M. stromeri between 500,000 and 2,000,000 years ago, perhaps in Beringia. The species appeared in the Great Basin and the Rockies by 750,000 years ago. The oldest recorded fossil find originates from Cathedral Cave, White Pine County, Nevada, and dates back 750,000 to 950,000 years ago.[12] Prairie dog fossils have been found in six sites that yield ferrets, thus indicating that the association between the two species is an old one.[13] Anecdotal observations and 42% of examined fossil records indicated that any substantial colony of medium- to large-sized colonial ground squirrels, such as Richardson's ground squirrels, may provide a sufficient prey base and a source of burrows for black-footed ferrets. This suggests that the black-footed ferret and prairie dogs did not historically have an obligate predator–prey relationship.[12] The species has likely always been rare, and the modern black-footed ferret represents a relict population. A reported occurrence of the species is from a late Illinoian deposit in Clay County, Nebraska, and it is further recorded from Sangamonian deposits in Nebraska and Medicine Hat, Alberta. Fossils have also been found in Alaska dating from the Pleistocene.[13][11]
The black-footed ferret has a long, slender body with black outlines on its paws, ears, parts of its face and its tail. The forehead is arched and broad, and the muzzle is short. It has few whiskers, and its ears are triangular, short, erect and broad at the base. The neck is long and the legs short and stout. The toes are armed with sharp, very slightly arched claws. The feet on both surfaces are covered in hair, even to the soles, thus concealing the claws.[14] It combines several physical features common in both members of the subgenus Gale (least and short-tailed weasels) and Putorius (European and steppe polecats). Its skull resembles that of polecats in its size, massiveness and the development of its ridges and depressions, though it is distinguished by the extreme degree of constriction behind the orbits where the width of the cranium is much less than that of the muzzle.
Although similar in size to polecats, its attenuate body, long neck, very short legs, slim tail, large orbicular ears and close-set pelage is much closer in conformation to weasels and stoats.[15] The dentition of the black-footed ferret closely resembles that of the European and steppe polecat, though the back lower molar is vestigial, with a hemispherical crown which is too small and weak to develop the little cusps which are more apparent in polecats.[15] It differs from the European polecat by the greater contrast between its dark limbs and pale body and the shorter length of its black tail-tip. In contrast, differences from the steppe polecat of Asia are slight, to the point where the two species were once thought to be conspecific.[13] The only noticeable differences between the black-footed ferret and the steppe polecat are the former's much shorter and coarser fur, larger ears, and longer post molar extension of the palate.[16]
Males measure 500–533 millimetres (19.7–21.0 in) in body length and 114–127 millimetres (4.5–5.0 in) in tail length, thus constituting 22–25% of its body length. Females are typically 10% smaller than males.[13] It weighs 650–1,400 grams (1.43–3.09 lb).[17] Captive-bred ferrets used for the reintroduction projects were found to be smaller than their wild counterparts, though these animals rapidly attained historical body sizes once released.[18]
The base color is pale yellowish or buffy above and below. The top of the head and sometimes the neck is clouded by dark-tipped hairs. The face is crossed by a broad band of sooty black, which includes the eyes. The feet, lower parts of the legs, the tip of the tail and the preputial region are sooty-black. The area midway between the front and back legs is marked by a large patch of dark umber-brown, which fades into the buffy surrounding parts. A small spot occurs over each eye, with a narrow band behind the black mask. The sides of the head and the ears are dirty-white in color.[16]
The black-footed ferret is solitary, except when breeding or raising litters.[4][5] It is nocturnal[4][19] and primarily hunts for sleeping prairie dogs in their burrows.[20] It is most active above ground from dusk to midnight and 4 am to mid-morning.[7] Aboveground activity is greatest during late summer and early autumn when juveniles become independent.[7] Climate generally does not limit black-footed ferret activity,[5][7] but it may remain inactive inside burrows for up to 6 days at a time during winter.[21]
Female black-footed ferrets have smaller home ranges than males. Home ranges of males may sometimes include the home ranges of several females.[5] Adult females usually occupy the same territory every year. A female that was tracked from December to March occupied 39.5 acres (16 ha). Her territory was overlapped by a resident male that occupied 337.5 acres (137 ha) during the same period. The average density of black-footed ferrets near Meeteetse, Wyoming, is estimated at one black-footed ferret to 148 acres (60 ha). As of 1985, 40 to 60 black-footed ferrets occupied a total of 6,178 to 7,413 acres (2,500 to 3,000 ha) of white-tailed prairie dog habitat.[4] From 1982 to 1984, the average year-round movement of 15 black-footed ferrets between white-tailed prairie dog colonies was 1.6 miles/night (2.5 km) (with a spread of 1.1 miles or 1.7 km). Movement of black-footed ferrets between prairie dog colonies is influenced by factors including breeding activity, season, sex, intraspecific territoriality, prey density, and expansion of home ranges with declining population density.[5][22] Movements of black-footed ferrets have been shown to increase during the breeding season; however, snow-tracking from December to March over a 4-year period near Meeteetse, Wyoming revealed that factors other than breeding were responsible for movement distances.[5]
Temperature is positively correlated with distance of black-footed ferret movement.[5] Snow-tracking from December to March over a 4-year period near Meeteetse, Wyoming, revealed that movement distances were shortest during winter and longest between February and April, when black-footed ferrets were breeding and white-tailed prairie dogs emerged from hibernation. Nightly movement distance of 170 black-footed ferrets averaged 0.87 miles (1.40 km) (range 0.001 to 6.91 miles (0.0016 to 11.1206 kilometres)). Nightly activity areas of black-footed ferrets ranged from 1 to 337.5 acres (0 to 137 ha)), and were larger from February to March (110.2 acres (45 ha)) than from December to January (33.6 acres (14 ha)).[5] Adult females establish activity areas based on access to food for rearing young. Males establish activity areas to maximize access to females, resulting in larger activity areas than those of females.[5]
Prey density may account for movement distances. Black-footed ferrets may travel up to 11 miles (18 km) to seek prey, suggesting that they will interchange freely among white-tailed prairie dog colonies that are less than 11 miles (18 km) apart. In areas of high prey density, black-footed ferret movements were nonlinear in character, probably to avoid predators.[5] From December to March over a 4-year study period, black-footed ferrets investigated 68 white-tailed prairie dog holes per 1 mile (1.6 km) of travel/night. Distance traveled between white-tailed prairie dog burrows from December to March averaged 74.2 feet (22.6 m) over 149 track routes.[5]
The reproductive physiology of the black-footed ferret is similar to that of the European polecat and the steppe polecat. It is probably polygynous, based on data collected from home range sizes, skewed sex ratios, and sexual dimorphism.[5][22] Mating occurs in February and March.[5][21] When a male and female in estrus encounter each other, the male sniffs the genital region of the female, but does not mount her until after a few hours have elapsed, which is contrast to the more violent behavior displayed by the male European polecat. During copulation, the male grasps the female by the nape of the neck, with the copulatory tie lasting from 1.5 to 3.0 hours.[13] Unlike other mustelids, the black-footed ferret is a habitat specialist with low reproductive rates.[22] In captivity, gestation of black-footed ferrets lasts 42–45 days. Litter size ranges from one to five kits.[19] Kits are born in May and June[23] in prairie dog burrows.[4] Kits are altricial and are raised by their mother for several months after birth. Kits first emerge above ground in July, at 6 weeks old.[7][22][23] They are then separated into individual prairie dog burrows around their mother's burrow.[7] Kits reach adult weight and become independent several months following birth, from late August to October.[7][22] Sexual maturity occurs at the age of one year.[7]
Intercolony dispersal of juvenile black-footed ferrets occurs several months after birth, from early September to early November. Dispersal distances may be short or long. Near Meeteetse, Wyoming, 9 juvenile males and three juvenile females dispersed 1 to 4 mi (1.6 to 6.4 km) following litter breakup. Four juvenile females dispersed a short distance (<0.2 mi (0.32 km)), but remained on their natal area.[22]
Up to 90% of the black-footed ferret's diet is composed of prairie dogs.[6][7] The remaining 10% of their diet is composed of small rodents, and Lagomorphs.[24] Their diet varies depending on geographic location. In western Colorado, Utah, Wyoming, and Montana, black-footed ferrets are historically associated with white-tailed prairie dogs and were forced to find alternative prey when white-tailed prairie dogs entered their four-month hibernation cycle.[19] In Wyoming, alternative prey items consumed during white-tailed prairie dog hibernation included voles (Microtus spp.) and mice (Peromyscus and Mus spp.) found near streams. In South Dakota, black-footed ferrets associate with black-tailed prairie dogs. Because black-tailed prairie dogs do not hibernate, little seasonal change in black-footed ferret diet is necessary.[5][19]
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In Mellette County, South Dakota, black-tailed prairie dog remains occurred in 91% of 82 black-footed ferret scats. Mouse remains occurred in 26% of scats. Mouse remains could not be identified to species; however, deer mice, northern grasshopper mice, and house mice were captured in snap-trap surveys. Potential prey items included thirteen-lined ground squirrels, plains pocket gophers, mountain cottontails, upland sandpipers, horned larks, and western meadowlarks.[7]
Based on 86 black-footed ferret scats found near Meeteetse, Wyoming, 87% of their diet was composed of white-tailed prairie dogs. Other food items included deer mice, sagebrush voles, meadow voles, mountain cottontails, and white-tailed jackrabbits. Water is obtained through consumption of prey.[4]
A study published in 1983 modeling metabolizable energy requirements estimated that one adult female black-footed ferret and her litter require about 474 to 1,421 black-tailed prairie dogs per year or 412 to 1,236 white-tailed prairie dogs per year for sustenance. They concluded that this dietary requirement would require protection of 91 to 235 acres (37 to 95 ha) of black-tailed prairie dog habitat or 413 to 877 acres (167 to 355 ha) of white-tailed prairie dog habitat for each female black-footed ferret with a litter.[25]
The historical range of the black-footed ferret was closely correlated with, but not restricted to, the range of prairie dogs (Cynomys spp.). Its range extended from southern Alberta and southern Saskatchewan south to Texas, New Mexico, and Arizona.[13] As of 2007, the only known wild black-footed ferret population was located on approximately 6,000 acres (2,400 hectares) in the western Big Horn Basin near Meeteetse, Wyoming.[4][5][6][21][22] Since 1990, black-footed ferrets have been reintroduced to the following sites: Shirley Basin, Wyoming; UL Bend National Wildlife Refuge and Fort Belknap Indian Reservation, Montana; Conata Basin/Badlands, Buffalo Gap National Grassland, and the Cheyenne River Sioux Reservation in South Dakota; Aubrey Valley, Arizona; Rocky Mountain Arsenal National Wildlife Refuge and Wolf Creek in Colorado; Coyote Basin, straddling Colorado and Utah, northern Chihuahua, Mexico,[23] and Grasslands National Park, Canada [26]
Historical habitats of the black-footed ferret included shortgrass prairie, mixed-grass prairie, desert grassland, shrub steppe, sagebrush steppe,[22] mountain grassland, and semi-arid grassland.[13] Black-footed ferrets use prairie dog burrows for raising young, avoiding predators, and thermal cover.[4][7] Six black-footed ferret nests found near Mellette County, South Dakota, were lined with buffalo grass, prairie threeawn, sixweeks grass, and cheatgrass. High densities of prairie dog burrows provide the greatest amount of cover for black-footed ferrets.[4][5] Black-tailed prairie dog colonies contain a greater burrow density per acre than white-tailed prairie dog colonies, and may be more suitable for the recovery of black-footed ferrets.[4] The type of prairie dog burrow may be important for occupancy by black-footed ferrets. Black-footed ferret litters near Meeteetse, Wyoming, were associated with mounded white-tailed prairie dog burrows, which are less common than non-mounded burrows. Mounded burrows contain multiple entrances and probably have a deep and extensive burrow system that protects kits.[4] However, black-footed ferrets used non-mounded prairie dog burrows (64%) more often than mounded burrows (30%) near Meeteetse, Wyoming.[5]
Primary causes of mortality include habitat loss, human-introduced diseases, and indirect poisoning from prairie dog control measures.[7][19][21][23] Annual mortality of juvenile and adult black-footed ferrets over a 4-year period ranged from 59 to 83% (128 individuals) near Meeteetse, Wyoming.[22] During fall and winter, 50 to 70% of juveniles and older animals perish.[22] Average lifespan in the wild is probably only one year, but may be up to five years. Males have higher rates of mortality than females because of longer dispersal distances when they are most vulnerable to predators.[22]
Given an obligate dependence of black-footed ferrets on prairie dogs, black-footed ferrets are extremely vulnerable to prairie dog habitat loss. Habitat loss results from agriculture, livestock use, and other development.[23]
Black-footed ferrets are susceptible to numerous diseases. They are fatally susceptible to canine distemper virus,[13][22] introduced by striped skunks, common raccoons, red foxes, coyotes, and American badgers.[21] A short-term vaccine for canine distemper is available for captive black-footed ferrets, but no protection is available for young born in the wild. Black-footed ferrets are also susceptible to rabies, tularemia, and human influenza. They can directly contract sylvatic plague (Yersinia pestis), and epidemics in prairie dog towns may completely destroy the ferrets' prey base.[27]
Predators of black-footed ferrets include golden eagles, great horned owls, coyotes, American badgers, bobcats, prairie falcons, ferruginous hawks, and prairie rattlesnakes.[7][21][22]
Oil and natural gas exploration and extraction can have detrimental impacts on prairie dogs and black-footed ferrets. Seismic activity collapses prairie dog burrows. Other problems include potential leaks and spills, increased roads and fences, increased vehicle traffic and human presence, and an increased number of raptor perching sites on power poles. Traps set for coyotes, American mink, and other animals may harm black-footed ferrets.[6]
Native American tribes, including the Crow, Blackfoot, Sioux, Cheyenne, and Pawnee, used black-footed ferrets for religious rites and for food.[19] The species was not encountered during the Lewis and Clark Expedition, nor was it seen by Nuttall or Townsend, and it did not become known to modern science until it was first described in John James Audubon and John Bachman's Viviparous Quadrupeds of North America in 1851.[28]
It is with great pleasure that we introduce this handsome new species; ... [it] inhabits the wooded parts of the country to the Rocky Mountains, and perhaps is found beyond that range... When we consider the very rapid manner in which every expedition that has crossed the Rocky Mountains, has been pushed forward, we cannot wonder that many species have been entirely overlooked... The habits of this species resemble, as far as we have learned, those of [the European polecat]. It feeds on birds, small reptiles and animals, eggs, and various insects, and is a bold and cunning foe to the rabbits, hares, grouse, and other game of our western regions.
— Audubon and Bachman (1851)[28]
For a time, the black-footed ferret was harvested for the fur trade, with the American Fur Company having received 86 ferret skins from Pratt, Chouteau, and Company of St. Louis in the late 1830s. During the early years of predator control, black-footed ferret carcasses were likely discarded, as their fur was of low value. This likely continued after the passing of the Endangered Species Act of 1973, for fear of reprisals. The large drop in black-footed ferret numbers began during the 1800s through to the 1900s, as prairie dog numbers declined because of control programs and the conversion of prairies to croplands.[29]
Sylvatic plague, a disease caused by Yersinia pestis introduced into North America, also contributed to the prairie dog die-off, though ferret numbers declined proportionately more than their prey, thus indicating other factors may have been responsible. Plague was first detected in South Dakota in a coyote in 2004, and then in about 50,000 acres (20,000 ha) of prairie dogs on Pine Ridge Reservation in 2005. Thereafter 7,000 acres (2,800 ha) of prairie dog colonies were treated with insecticide (DeltaDust) and 1,000 acres (400 ha) of black-footed ferret habitat were prophylactically dusted in Conata Basin in 2006–2007. Nevertheless, plague was proven in ferrets in May 2008. Since then each year 12,000 acres (4,900 ha) of their Conata Basin habitat is dusted and about 50–150 ferrets are immunized with plague vaccine.[30] Ferrets are unlikely to persist through plague episodes unless there are management efforts that allow access to prey resources at a wider region or actions that could substantially reduce the plague transmission.[31] Implementing efforts to conserve large prairie dog landscapes and plague mitigation tools are very important in conserving the black-footed ferrets' population.[31]
Inbreeding depression may have also contributed to the decline, as studies on black-footed ferrets from Meeteetse, Wyoming revealed low levels of genetic variation. Canine distemper devastated the Meeteetse ferret population in 1985. A live virus vaccine originally made for domestic ferrets killed large numbers of black-footed ferrets, thus indicating that the species is especially susceptible to distemper.[17]
The black‐footed ferret experienced a recent population bottleneck in the wild followed by a more than 30-year recovery through ex situ breeding and then reintroduction into its native range. As such, this sole endemic North American ferret allows examining the impact of a severe genetic restriction on subsequent biological form and function, especially on reproductive traits and success. The black‐footed ferret was listed as endangered by the United States Fish and Wildlife Service (USFWS) in 1967. Declared extinct in 1979, a residual wild population was discovered in Meeteetse, Wyoming, in 1981. This cohort eventually grew to 130 individuals and was then nearly extirpated by sylvatic plague, Yersinia pestis, and canine distemper virus, Canine morbillivirus, with eventually 18 animals remaining.[32] These survivors were captured from 1985 to 1987 to serve as the foundation for the black‐footed ferret ex situ breeding program. Seven of those 18 animals produced offspring that survived and reproduced, and with currently living descendants, are the ancestors of all black‐footed ferrets now in the ex situ (about 320) and in situ (about 300) populations.[33]
The black-footed ferret is an example of a species that benefits from strong reproductive science.[34] A captive-breeding program was initiated in 1987, capturing 18 living individuals and using artificial insemination. This is one of the first examples of assisted reproduction contributing to conservation of an endangered species in nature.[34] The U.S. Fish and Wildlife Service, state and tribal agencies, private landowners, conservation groups, and North American zoos have actively reintroduced ferrets back into the wild since 1991. Beginning in Shirley Basin[35] in Eastern Wyoming, reintroduction expanded to Montana, 6 sites in South Dakota in 1994, Arizona, Utah, Colorado, Saskatchewan, Canada and Chihuahua, Mexico. The Toronto Zoo has bred hundreds, most of which were released into the wild.[36] Several episodes of Zoo Diaries show aspects of the tightly controlled breeding. In May 2000, the Canadian Species at Risk Act listed the black-footed ferret as being an extirpated species in Canada.[37] A population of 35 animals was released into Grasslands National Park in southern Saskatchewan on October 2, 2009,[38] and a litter of newborn kits was observed in July 2010.[39] Reintroduction sites have experienced multiple years of reproduction from released individuals.
The black-footed ferret was first listed as endangered in 1967 under the Endangered Species Preservation Act, and was re-listed on January 4, 1974, under the Endangered Species Act. In September 2006, South Dakota's ferret population was estimated to be around 420, with 250 (100 breeding adults consisting of 67 females and 33 males) in Eagle Butte, South Dakota, which is 100,000 acres (40,000 ha), less than 3% of the public grasslands in South Dakota, 70 miles (110 km) east of Rapid City, South Dakota, in the Buffalo Gap National Grassland bordering Badlands National Park, 130 ferrets northeast of Eagle Butte, SD, on Cheyenne River Indian Reservation, and about 40 ferrets on the Rosebud Indian Reservation.[40] Arizona's Aubrey Valley ferret population was well over 100 and a second reintroduction site with around 50 animals is used. An August 2007 report in the journal Science counted a population of 223 in one area of Wyoming (the original number of reintroduced ferrets, most of which died, was 228), and an annual growth rate of 35% from 2003 to 2006 was estimated.[41][42] This rate of recovery is much faster than for many endangered species, and the ferret seems to have prevailed over the previous problems of disease and prey shortage that hampered its improvement.[42] As of 2007, the total wild population of black-footed ferrets in the U.S. was well over 650 individuals, plus 250 in captivity. In 2008, the IUCN reclassified the species as "globally endangered", a substantial improvement since the 1996 assessment, when it was considered extinct in the wild, as the species was indeed only surviving in captivity. In 2016, NatureServe considered the species Critically Imperiled.[43]
As of 2013, about 1,200 ferrets are thought to live in the wild.[44] These wild populations are possible due to the extensive breeding program that releases surplus animals to reintroduction sites, which are then monitored by USFWS biologists for health and growth. However, the species cannot depend just on ex situ breeding for future survival, as reproductive traits such as pregnancy rate and normal sperm motility and morphology have been steadily declining with time in captivity.[45] These declining markers of individual and population health are thought to be due to increased inbreeding, an occurrence often found with small populations or ones that spend a long time in captivity.[46][47]
Conservation efforts have been opposed by stock growers and ranchers, who have traditionally fought prairie dogs. In 2005, the U.S. Forest Service began poisoning prairie dogs in private land buffer zones of the Conata Basin of Buffalo Gap National Grassland. Because 10–15 ranchers complained the measure was inadequate, the forest service advised by Mark Rey, then Undersecretary of Agriculture, expanded its "prairie-dog management" in September 2006 to all of South Dakota's Buffalo Gap and the Fort Pierre National Grassland, and also to the Oglala National Grassland in Nebraska, against opinions of biologists in the U.S. Fish and Wildlife Service. Following exposure by conservation groups including the Climate, Community & Biodiversity Alliance and national media[48] public outcry and a lawsuit mobilized federal officials, and the poisoning plan was revoked.
The contradictory mandates of the two federal agencies involved, the USFWS and the U.S. Forest Service, are exemplified in what the Rosebud Sioux tribe experienced: The ferret was reintroduced by the USFWS, which according to the tribe promised to pay more than $1 million a year through 2010. On the other hand, the tribe was also contracted for the U.S. Forest Service prairie dog poisoning program. The increasing numbers of ferrets led to conflicts between the tribe's Cheyenne River Sioux Tribe Game, Fish and Parks Department and the Tribal Land Enterprise Organization. When the federal government started an investigation of the tribe's prairie dog management program, threatening to prosecute tribal employees or agents carrying out the management plan in the ferret reintroduction area, the tribal council passed a resolution in 2008, asking the two federal agencies to remove ferrets, and reimburse the tribe for its expenses for the ferret recovery program.[49]
Employees of the San Diego Zoo, the conservation organization Revive & Restore, the ViaGen Pets and Equine Company and the U.S. Fish and Wildlife Service have teamed up to clone a black-footed ferret. In 2020, a team of scientists cloned a female named Willa, who died in the mid-1980s and left no living descendants. Her clone, a female named Elizabeth Ann, was born on December 10, 2020, making her the first North American endangered species to be cloned.[10] Scientists hope that the contribution of this individual will alleviate the effects of inbreeding and help black-footed ferrets better cope with plague. Experts estimate that this female's genome contains three times as much genetic diversity as any of the modern black-footed ferrets.[50]
In the year 2020, black-footed ferrets[51] were used to test an experimental COVID-19 vaccine in Colorado.[52]
In 2023, the black-footed ferret was featured on a United States Postal Service Forever stamp as part of the Endangered Species set, based on a photograph from Joel Sartore's Photo Ark. The stamp was dedicated at a ceremony at the National Grasslands Visitor Center in Wall, South Dakota.[53]
This article incorporates public domain material from Mustela nigripes. United States Department of Agriculture.
The black-footed ferret (Mustela nigripes), also known as the American polecat or prairie dog hunter, is a species of mustelid native to central North America.
The black-footed ferret is roughly the size of a mink and is similar in appearance to the European polecat and the Asian steppe polecat. It is largely nocturnal and solitary, except when breeding or raising litters. Up to 90% of its diet is composed of prairie dogs.
The species declined throughout the 20th century, primarily as a result of decreases in prairie dog populations and sylvatic plague. It was declared extinct in 1979, but a residual wild population was discovered in Meeteetse, Wyoming in 1981. A captive-breeding program launched by the United States Fish and Wildlife Service resulted in its reintroduction into eight western US states, Canada, and Mexico from 1991 to 2009. As of 2015, over 200 mature individuals are in the wild across 18 populations, with four self-sustaining populations in South Dakota, Arizona, and Wyoming. It was first listed as "endangered" in 1982, then listed as "extinct in the wild" in 1996 before being upgraded back to "endangered" in the IUCN Red List in 2008. In February 2021, the first successful clone of a black-footed ferret, a female named Elizabeth Ann, was introduced to the public.
El turón patinegro americano,[1] o turón patinegro [2] (Mustela nigripes) es una especie de mamífero carnívoro de Norteamérica. Es un miembro de la diversa familia de los mustélidos que incluye comadrejas, visones, turones, martas, nutrias, y tejones. Está muy relacionado con Mustela eversmanii de Rusia.[3] Vive en el centro de Estados Unidos desde el norte al sur en matorrales áridos y pastizales. Gran parte de su dieta la constituyen los perritos llaneros. Está en peligro de extinción por lo que hay unas leyes muy estrictas para su protección. Es muy parecido al hurón doméstico, muchas veces es confundido con él.
La longitud de su cuerpo es de 35 a 50 cm, con una cola muy forrada de 15 cm, y pueden llegar a pesar 1 kg. Su piel es blanca en la base, pero se oscurece en las puntas, haciéndolos parecer de un color amarillento-marrón en general, con pies negros que comienzan en la cadera y terminan en la punta de la cola, y una máscara distintiva negra. Estos armonizan bien con el ecosistema de pradera en el cual ellos viven.[4]
Son nocturnos y pasan la mayor parte del tiempo en sus madrigueras bajo tierra (a veces incluso duermen en las madrigueras de los perritos de la pradera). No hibernan, pero en las épocas de frío disminuye su actividad.
El 90% de su dieta la forman los perritos de la pradera y lo demás consiste en ratas, ratones, pájaros, ardillas, conejos y a veces en reptiles e insectos. Los machos son un 10% más grandes que la hembra y llegan a pesar 1 kilo. Un hurón solo come aproximadamente 100 perritos de la pradera en un año y no puede sobrevivir sin el acceso a las colonias grandes de ellos. Típicamente una colonia de perro de pradera que abarca 150 acres es lo suficientemente estable como para alimentar a un adulto.
La reproducción comienza entre marzo y abril, y la gestación dura de 41 a 43 días. El número de crías varía de 1 a 7, pero normalmente nacen tan solo 3 o 4.
La especie se extinguió en estado silvestre en la década de 1980, por lo que la captura de individuos para la cría en cautiverio ha sido exitosa en este caso. Actualmente solo existen unos cientos de individuos entre los cautivos y los reintroducidos.
La primera población se reintrodujo en el estado de Wyoming, Estados Unidos en 1991. Desde 1987, unos 6000 hurones de pies negros han nacido en cautiverio y desde 1991 se han liberado unos 2000. Para 2008 existían cerca de 300 turones cautivos y aproximadamente 500 nacidos en estado salvaje.[1]
La pérdida de su hábitat de pradera, la reducción drástica de la población de perritos de la pradera (tanto por la pérdida de hábitat como por envenenamiento), así como los efectos del moquillo y la peste bubónica han contribuido a la casi extinción de la especie durante los siglos XIX y XX. Incluso antes de que sus efectivos disminuyeran, el turón patinegro era muy raramente visto: oficialmente, no fue reconocida como especie por la ciencia hasta 1851, después de la publicación de un libro por el naturalista John James Audubon y el reverendo John Bachman. Incluso entonces, su existencia fue cuestionada, ya que no se documentó ningún otro turón patinegro durante más de veinte años.
El plan de recuperación mantiene de diez o más poblaciones salvajes autónomas separadas. Los biólogos han logrado la hazaña de incrementar la población a 1500.[cita requerida]
Datos: Q402885
Multimedia:
Especies: Mustela nigripes
El turón patinegro americano, o turón patinegro (Mustela nigripes) es una especie de mamífero carnívoro de Norteamérica. Es un miembro de la diversa familia de los mustélidos que incluye comadrejas, visones, turones, martas, nutrias, y tejones. Está muy relacionado con Mustela eversmanii de Rusia. Vive en el centro de Estados Unidos desde el norte al sur en matorrales áridos y pastizales. Gran parte de su dieta la constituyen los perritos llaneros. Está en peligro de extinción por lo que hay unas leyes muy estrictas para su protección. Es muy parecido al hurón doméstico, muchas veces es confundido con él.
Mustjalg-tuhkur (Mustela nigripes) on ohustatuimas seisundis Põhja-Ameerikas elav imetaja, kelle asurkond oli kunagi Suurel tasandikul väga suur. Kõik praegused Põhja-Ameerikas elavad mustjalg-tuhkrud pärinevad 1981. aastal Wyomingi osariigist Meeteetse lähedal asuvast karjafarmist avastatud seitsmest esivanemast.
Mustjalg-tuhkrud toituvad peamiselt rohtlahaukuritest.
Mustela nigripes Mustela generoko animalia da. Karniboro barruko Mustelinae azpifamilia eta Mustelidae familian sailkatuta dago.
Mustela nigripes Mustela generoko animalia da. Karniboro barruko Mustelinae azpifamilia eta Mustelidae familian sailkatuta dago.
Mustajalkahilleri (Mustela nigripes) on Pohjois-Amerikassa elävä näätäeläin. Ne ovat noin 45 cm pitkiä ja painavat noin yhden kilogramman. Ne metsästävät öisin ja niiden ruokavalio koostuu lähes pelkästään preeriakoirista. Yksi mustajalkahilleriperhe voi syödä vuodessa jopa 700 preeriakoiraa. Päivisin mustajalkahillerit hakeutuvat suojaan preeriakoirien pesäkoloihin.
Mustajalkahillerit olivat harvinainen näky jo ennen kuin ne tulivat uhanalaisiksi. Ne tunnisti omaksi lajikseen vasta John James Audubon ja John Bachman vuonna 1851. Heidän havaintonsa kyseenalaistettiin, ja seuraava havainto mustajalkahillereistä tehtiin vasta yli 20 vuoden jälkeen.
Mustajalkahilleri julistettiin Kanadassa sukupuuttoon kuolleeksi vuonna 1937 ja Yhdysvalloissa uhanalaiseksi vuonna 1967. Vuonna 1986 maailmassa arveltiin olevan elossa vain 50 yksilöä. 18 niistä otettiin kiinni ja ne on saatu lisääntymään vankeudessa.
Vuodesta 1991 lähtien mustajalkahillereitä on yritetty palauttaa luontoon. Niitä on vapautettu kahdeksan osavaltion alueella Yhdysvalloissa sekä yhdessä kohteessa Meksikossa. Istutuksia on tehty 18 eri alueella, joista kolmessa mustajalkahilleripopulaatiosta on muodostunut omavaraisia. Omavaraiset populaatiot sijaitsevat Pohjois-Dakotan ja Wyomingin alueella. Kevään 2008 laskennan mukaan luonnossa elää noin 500 lisääntymiskykyistä aikuista mustajalkahilleriä.[1]
Lajin sukupuuttoon oli johtamassa sen luontaisen elinympäristön häviäminen, preeriakoirien lukumäärän raju lasku sekä taudit.[1]
Mustajalkahilleri (Mustela nigripes) on Pohjois-Amerikassa elävä näätäeläin. Ne ovat noin 45 cm pitkiä ja painavat noin yhden kilogramman. Ne metsästävät öisin ja niiden ruokavalio koostuu lähes pelkästään preeriakoirista. Yksi mustajalkahilleriperhe voi syödä vuodessa jopa 700 preeriakoiraa. Päivisin mustajalkahillerit hakeutuvat suojaan preeriakoirien pesäkoloihin.
Mustajalkahillerit olivat harvinainen näky jo ennen kuin ne tulivat uhanalaisiksi. Ne tunnisti omaksi lajikseen vasta John James Audubon ja John Bachman vuonna 1851. Heidän havaintonsa kyseenalaistettiin, ja seuraava havainto mustajalkahillereistä tehtiin vasta yli 20 vuoden jälkeen.
Mustela nigripes
Le Putois à pieds noirs[1] (Mustela nigripes), est un petit mammifère carnivore de la famille des mustélidés, habitant de la prairie d'Amérique du Nord. Il est également appelé furet à pieds noirs, traduction littérale de son nom d'origine « black footed ferret », ou encore putois américain au Canada[2]. Il ne doit pas être confondu avec la variante, dite « furet américain », de son cousin domestique le furet (Mustela putorius furo). Mustela nigripes est étroitement apparenté au putois des steppes (Mustela eversmannii) originaire de Russie[3]. Le putois à pieds noirs est la seule espèce de putois indigène en Amérique du Nord[4].
Le putois à pieds noirs est un mustélidé de la taille et de l'aspect d'un furet. La taille moyenne est d'environ 50 cm, le poids moyen est de 580 g pouvant atteindre 1 100 g[4], les femelles sont plus petites que les mâles (10 %). Il a une courte queue recouverte de pelage, des oreilles ovales et saillantes et de fortes pattes. Son poil de garde est blanc alors que le bout des poils est brun, ce qui lui donne une apparence champagne foncé. Un masque complet brun marque ses yeux. Le patron de la robe est zibeline avec les pattes et le bout de la queue marron. Le museau, le front, les oreilles, la gorge et le début de la queue sont blancs. Le pelage couvre également les coussinets[5].
Ses grands yeux noirs et ses larges oreilles[4] suggèrent qu'il a une bonne acuité auditive et visuelle, mais l'odorat reste fondamental pour ce prédateur souterrain[6].
Le putois à pieds noirs est un carnivore principalement nocturne étroitement associé au chien de prairie (Cynomys), bien qu'il ait été prouvé[7] qu'il puisse également être associé aux populations d'écureuils terrestres (Bermoohilus armatus)[8].
Le putois à pieds noirs est avant tout un prédateur direct du chien de prairie sauvage, dont il utilise également les terriers pour se reproduire. La femelle installe son nid dans le terrier de ses proies dans lequel elle met bas de 3 à 6 petits. La part du chien de prairie dans son alimentation est estimée entre 87 et 91 %. Un chien de prairie adulte représente 6 à 7 jours de ration alimentaire pour un putois à pieds noirs[9]. Le putois à pieds noirs se nourrit également de proies d'opportunité, lagomorphes, souris, oiseaux et insectes[10].
Sa couleur et sa robe sont un camouflage parfaitement adapté à l'environnement de la prairie, ce qui le rend difficile à voir quand il est immobile. Il chasse ses proies à l'odorat sous terre dans le noir[6].
La quasi-extinction de cette espèce serait due aux menaces pesant sur leur principale ressource alimentaire, le chien de prairie sauvage, à la maladie de Carré et à une maladie appelée Sylvatic plague (en)[11] » similaire à la peste bubonique[8] .
Le putois à pieds noirs est considéré comme une espèce en danger d'après l'U. S. Fish and Wildlife Service (USFWS). Il s'est éteint en tant qu'espèce sauvage au Canada en 1937, et a été classé espèce en danger aux États-Unis en 1967[8].
Alors que l'espèce était considérée comme éteinte dans la nature au statut UICN EW (Éteint dans la nature), un dernier peuplement sauvage a été découvert par hasard près de Meeteetse dans l'État du Wyoming en 1981. Un chien de ferme a tué un animal inconnu qui fut identifié comme un Mustela nigripes[12]. Une enquête rapidement menée a permis de découvrir un peuplement survivant de l'espèce, jusqu'alors inconnu. Ce peuplement comptait 130 animaux à sa découverte. Un suivi de cette population a montré qu'elle s'éteignait rapidement[8].
En 1986, le putois à pieds noirs était le mammifère le plus en danger du monde, avec une population réduite à 18 animaux. De 1986 à 1987 le "Wyoming Game and Fish Department" a procédé à la capture des 18 animaux restants pour leur protection et pour établir un programme de reproduction intensif[13].
À cette date, la totalité de la population mondiale de putois à pieds noirs était alors réduite à 50 individus en captivité[14].
Sept animaux de ce peuplement ont été répartis dans des zoos[15] et des universités dans le cadre du programme de reproduction. Des centaines d'animaux reproduits en captivité ont été relâchés dans l'habitat original, mais en 1997 seuls 5 d'entre eux ont pu être dénombrés. La peste sylvide, la maladie de Carré, et le faible taux de reproduction ont fait presque échouer cette tentative[14].
Presque car à partir de 1997, l'établissement de colonies dans des zones indemnes de Sylvatic plague[4], le soutien des fermiers, des groupes de protection de la nature, des Indiens Shoshone[16] dans les zones de réintroduction ont permis de rétablir une population stable de chiens de prairie et corrélativement de putois à pieds noirs[14].
En 1998, un jalon important est atteint : le nombre d'animaux en liberté dépasse de nouveau le nombre d'animaux en captivité[17].
Ainsi, après avoir frôlé l'extinction, l'espèce a été réintroduite, au départ dans le Wyoming, puis dans plusieurs États d'Amérique, dont l'Arizona[18] et le Montana, mais aussi dans l'État de Chihuahua, au Mexique. Le Canada a décliné l'offre de réintroduction car l'analyse menée par le service canadien de la faune a montré que la population résiduelle de chiens de prairie dans les zones de réintroduction potentielle était insuffisante pour assurer la survie de l'espèce[4]. En conséquence, aucun projet de réintroduction n'est à ce jour démarré au Canada[5] bien que le Canada collabore très activement au programme de réintroduction par ses élevages en captivité[19]. En 2009 une étude dans le cadre du programme « SARA » (Species At Risk Act) envisage une réintroduction de l'animal dans son habitat d'origine au sein du Parc national des Prairies. L'étude conclut que la petitesse (10 km2) de l'habitat disponible constitue un « vrai défi » mais semble ouvrir la porte à cette réintroduction[20].
En dépit de ce succès impressionnant, il s'agissait encore, en 2005, du mammifère le plus rare du continent nord-américain, et donc d'une espèce toujours gravement menacée, bien que la population réintroduite connaisse une croissance de 35 % par an[21]. À cette date l'UICN a reclassifié l'espèce du niveau EW (éteint dans la nature) au niveau EN (en danger).
En 2007 la population stable de putois à pieds noirs était de 600 animaux[14].
L'objectif actuel à l'horizon 2010 des programmes de réintroduction est d'obtenir plus de 10 populations sauvages auto-suffisantes, soit plus de 1 500 animaux, chaque population comportant au moins 30 adultes reproducteurs. Cet objectif permettrait le passage du niveau UICN EN (en danger) au niveau UICN VU (Vulnérable)[22].
Ce remarquable programme de réintroduction est géré par le "Black-Footed Ferret Recovery Program[23]"
Par ailleurs, le putois à pieds noirs est l'un des personnages principaux de la nouvelle de science-fiction de Ken Wharton, Through the Looking-Glass, qui doit son titre au récit célèbre de Lewis Carroll.
Mustela nigripes
Le Putois à pieds noirs (Mustela nigripes), est un petit mammifère carnivore de la famille des mustélidés, habitant de la prairie d'Amérique du Nord. Il est également appelé furet à pieds noirs, traduction littérale de son nom d'origine « black footed ferret », ou encore putois américain au Canada. Il ne doit pas être confondu avec la variante, dite « furet américain », de son cousin domestique le furet (Mustela putorius furo). Mustela nigripes est étroitement apparenté au putois des steppes (Mustela eversmannii) originaire de Russie. Le putois à pieds noirs est la seule espèce de putois indigène en Amérique du Nord.
Il furetto dai piedi neri (Mustela nigripes Audubon e Bachman, 1851), conosciuto nei luoghi d'origine anche come American polecat[2] («puzzola americana») o prairie dog hunter[3] («cacciatore di cani della prateria»), è un Mustelide originario delle regioni centrali del Nordamerica. Dal momento che ne rimangono solamente popolazioni piccole e poco numerose, viene classificato come specie in pericolo dalla IUCN.
Scoperta per la prima volta da Audubon e Bachman nel 1851, questa specie si è ridotta sempre più nel corso del XX secolo, prevalentemente a causa della diminuzione delle popolazioni di cani della prateria e delle epidemie di peste selvatica. Nel 1979 venne addirittura dichiarata estinta, fino a quando, nel 1981, il cane di Lucille Hogg non si presentò alla porta dell'abitazione di Meeteetse (Wyoming) con un furetto morto in bocca[4]. Le poche dozzine di esemplari rimasti continuarono a vivere nell'area fino a quando la specie non venne dichiarata estinta in natura nel 1987. Tuttavia, grazie ad un programma di riproduzione in cattività condotto dal Servizio Pesca e Fauna Selvatica degli Stati Uniti, tra il 1991 e il 2008 alcuni furetti sono stati reintrodotti in otto stati occidentali e in Messico. Attualmente in natura vi sono più di 1.000 esemplari adulti nati allo stato selvatico, suddivisi in 18 popolazioni, delle quali quattro autosufficienti in Dakota del Sud (due), Arizona e Wyoming[1][5].
Il furetto dai piedi neri ha all'incirca le dimensioni di un visone, e si differenzia dalla puzzola europea per il maggiore contrasto tra la colorazione scura delle zampe e quella chiara del corpo e per la minore lunghezza della coda, nera all'estremità. Al contrario, le differenze intercorrenti tra il furetto dai piedi neri e la puzzola delle steppe dell'Asia sono esigue, al punto che in passato i due erano considerati conspecifici[6]. Infatti, il furetto si distingue da quest'ultima solamente per avere manto più breve e ispido, orecchie più grandi ed estensione post-molare del palato più lunga[7].
Conduce prevalentemente vita notturna e solitaria, tranne che nel periodo riproduttivo e dell'allevamento dei piccoli[8][9]. Fino al 91% della sua dieta è composta da cani della prateria[10][11].
Come la sua stretta cugina, la puzzola delle steppe dell'Asia (della quale in passato era ritenuto conspecifico), il furetto dai piedi neri rappresenta una forma più specializzata della puzzola europea verso uno stile di vita carnivoro[2]. Molto probabilmente il furetto dai piedi neri discende da Mustela stromeri (antenato anche della puzzola europea e di quella delle steppe), una specie evolutasi in Europa nel Pleistocene medio[12]. Le analisi molecolari indicano che la puzzola delle steppe e il furetto dai piedi neri si separarono da Mustela stromeri tra i 500.000 e i 2.000.000 di anni fa, forse nel territorio dell'allora Beringia. La specie fece la sua comparsa nel Gran Bacino e sulle Montagne Rocciose 750.000 anni fa. I più antichi resti fossili ad essa attribuibili sono stati ritrovati nella Cathedral Cave, nella Contea di White Pine (Nevada), e risalgono a 750.000–950.000 anni fa[13]. In sei dei siti dove sono stati rinvenuti resti di furetto sono stati trovati anche fossili di cani della prateria, il che starebbe a significare che l'associazione tra le due specie si era già stabilita allora[6]. Tuttavia, come sembrerebbero indicare le osservazioni sul campo e il 42% dei siti fossili esaminati, anche una colonia medio-grande di scoiattoli di terra, come i citelli di Richardson, avrebbe potuto fornire prede sufficienti e rifugi sotterranei in abbondanza ai furetti. Ciò suggerisce che questi non abbiano stabilito un rapporto predatore-preda così stretto con i cani della prateria in epoca preistorica[13]. Probabilmente il furetto è sempre stato abbastanza raro, e gli esemplari attuali apparterrebbero a una popolazione relitta. I primi resti indicanti la presenza della specie provengono da un deposito dell'Illinoiano della Contea di Clay (Nebraska), ma essa è documentata anche in depositi del Sangamoniano del Nebraska e a Medicine Hat. Fossili risalenti al Pleistocene sono stati rinvenuti anche in Alaska[6][12].
Il furetto dai piedi neri ha il corpo molto lungo e la testa smussata. La fronte è arcuata e larga, e il muso è corto. Le vibrisse sono scarse, e le orecchie triangolari, brevi, erette e larghe alla base. Il collo è lungo e le zampe brevi e tozze. Le dita sono munite di artigli affilati e leggermente ricurvi. Tuttavia questi ultimi sono quasi invisibili, dal momento che l'intero piede, pianta compresa, è ricoperto di pelo[14]. Nell'animale si riscontrano caratteristiche fisiche comuni alle specie del sottogenere Gale (donnola, ermellino e donnola dalla lunga coda) e Putorius (puzzola europea e puzzola delle steppe). Il cranio ricorda quello delle puzzole nelle dimensioni, nella consistenza e nello sviluppo delle creste e depressioni, sebbene si distingua da quello di queste ultime per il grado estremo di costrizione dietro le orbite, dove la larghezza del cranio è minore di quella del muso. Malgrado le dimensioni simili a quelle delle puzzole, il corpo sottile, il collo lungo, le zampe molto corte, la coda sottile, le grandi orecchie rotonde e la costituzione del manto ricordano molto più le donnole e gli ermellini[15]. La dentatura del furetto dai piedi neri ricorda molto quella della puzzola europea e della puzzola delle steppe, ma l'ultimo molare inferiore è vestigiale, con una corona semisferica troppo piccola e debole per sviluppare le piccole cuspidi presenti nelle puzzole[15].
I maschi hanno il corpo lungo 500–533 mm e la coda lunga 114–127 mm, pari al 22-25% della lunghezza totale. Le femmine generalmente sono più piccole dei maschi del 10%[6]. Il peso si aggira sui 650-1.400 g[16]. Gli esemplari cresciuti in cattività impiegati nei programmi di reintroduzione avevano dimensioni inferiori di quelle dei loro simili selvatici, ma una volta rilasciati in natura hanno raggiunto rapidamente le dimensioni solite[17].
Il mantello ha una colorazione di base, sopra e sotto, giallognolo chiaro o beige. La sommità del capo e, talvolta, il collo sono ricoperti da peli dalle estremità di colore scuro. La faccia è attraversata da una larga fascia di pelo di colore nero sporco, che circonda gli occhi. Di colore nero sporco sono anche i piedi, la parte inferiore delle zampe, l'estremità della coda e la regione prepuziale. Sul dorso, nell'area compresa tra le zampe anteriori e posteriori, è presente una grossa chiazza scura color terra di Siena, che sbiadisce pian piano nel beige delle regioni circostanti. Sopra ogni occhio vi è una piccola macchia, e dietro la mascherina facciale nera corre una sottile fascia dello stesso colore. I lati della testa e le orecchie sono di colore bianco sporco[7].
Il furetto dai piedi neri conduce vita solitaria, tranne che nel periodo degli amori e dell'allevamento dei piccoli[8][9]. Ha abitudini notturne[8][18] e cattura prevalentemente i cani della prateria aggredendoli mentre dormono nelle loro tane[19]. Si spinge sul terreno perlopiù tra il tramonto e la mezzanotte e tra le quattro di mattina e metà mattinata[11]. L'attività a livello del suolo è maggiore durante la fine dell'estate e gli inizi dell'autunno, quando i giovani raggiungono l'indipendenza[11]. Le variazioni climatiche generalmente non limitano le attività dell'animale[9][11], ma durante l'inverno esso può rimanere al sicuro nella tana anche per 6 giorni di seguito[20].
Le femmine occupano territori più piccoli di quelli dei maschi. Quelli dei maschi, invece, possono talvolta sovrapporsi a quelli di più femmine[9]. Le femmine adulte occupano generalmente lo stesso territorio ogni anno. Una femmina monitorata dagli studiosi tra dicembre e marzo occupava un territorio di 16 ettari. Nello stesso periodo questo era compreso entro i confini del territorio di un maschio vasto 137 ettari. La densità media di furetti dai piedi neri nei pressi di Meeteetse (Wyoming) è stata stimata a un esemplare ogni 60 ettari. Nel 1985, 40-60 esemplari occupavano un'area di 2.500-3.000 ettari estesa su una colonia di cani della prateria dalla coda bianca[8]. Dal 1982 al 1984, gli spostamenti annuali medi di 15 furetti dai piedi neri tra le varie colonie di cani della prateria dalla coda bianca furono di 2,5 km per notte (con un range di 1,7 km). Lo spostamento dei furetti attraverso le colonie di cani della prateria è influenzato da vari fattori, come l'attività riproduttiva, la stagione, il sesso, la territorialità intraspecifica e la densità delle prede, mentre l'estensione dei territori è direttamente collegata alla densità di popolazione[9][21]. Il numero degli spostamenti è risultato maggiore durante la stagione degli amori; tuttavia, le tracce sulla neve osservate tra dicembre e marzo per un periodo di 4 anni nei pressi di Meeteetse (Wyoming) hanno rivelato che oltre alle abitudini riproduttive vi sono altri fattori responsabili di spostamenti su maggiori distanze[9].
La temperatura è positivamente collegata alla distanza degli spostamenti dei furetti[9]. Le suddette tracce sulla neve hanno rivelato che i movimenti sono più brevi durante l'inverno e più lunghi tra febbraio e aprile, quando i furetti si riproducono e i cani della prateria dalla coda bianca emergono dal letargo. La media degli spostamenti notturni di 170 esemplari è risultata essere di 1,40 km (con un range compreso tra 0,002 km e 11,12 km). Le aree di attività notturna dei furetti variano in estensione da 0 a 137 ettari, e sono più estese tra febbraio e marzo (45 ettari) che tra dicembre e gennaio (14 ettari)[9]. Le femmine adulte scelgono le proprie aree di attività sulla base delle risorse alimentari necessarie all'allevamento dei piccoli. I maschi, invece, basano le proprie scelte su un maggiore accesso alle femmine, il che li porta ad occupare territori maggiori di quelli delle compagne[9].
Anche la densità delle prede può influire sulla distanza degli spostamenti. I furetti possono spostarsi in cerca di cibo anche per 18 km, il che significa che possono passare da una colonia di cani della prateria dalla coda bianca all'altra, se queste distano meno di 18 km. Nelle aree dove vi è maggiore densità di prede, i movimenti dei furetti non sono risultati lineari, probabilmente per eludere i predatori[9]. Da dicembre a marzo, su un periodo di studio di 4 anni, i furetti hanno perlustrato 68 tane di cani della prateria ogni 1,6 km di spostamento per notte. La distanza percorsa tra le tane di cani della prateria tra dicembre e marzo, osservata su 149 percorsi di tracce, è stata in media di 22,6 m[9].
La fisiologia riproduttiva del furetto dai piedi neri è simile a quella della puzzola europea e della puzzola delle steppe. La specie è probabilmente poliginica, almeno stando a quanto si è potuto apprendere dai dati raccolti sulle dimensioni dei territori, sul rapporto tra i sessi e sul dimorfismo sessuale[9][21]. L'accoppiamento avviene in febbraio e marzo[9][20]. Quando un maschio e una femmina in estro si incontrano, il primo annusa la regione genitale dell'altra, ma proverà a montarla solamente trascorse alcune ore, diversamente da quanto avviene tra le puzzole europee, nelle quali il maschio assume un comportamento molto più violento. Durante la copula, il maschio stringe con i denti la nuca della femmina, e la cravatta copulatoria dura 1,5-3 ore[6]. Diversamente da altri Mustelidi, il furetto dai piedi neri è un animale specialista con un basso tasso riproduttivo[21]. In cattività, la gestazione dura 42-45 giorni. Ogni cucciolata è composta da 1-5 piccoli[18]. Questi nascono in maggio e giugno[22] all'interno della tana di un cane della prateria[8]. Essi sono del tutto inetti e vengono allevati dalla madre per alcuni mesi dopo la nascita. Escono per la prima volta dalla tana in luglio, all'età di 6 settimane[11][21][22]. Verso questa età iniziano a separarsi e ad occupare proprie gallerie attorno alla tana della madre[11]. I giovani completano lo sviluppo e raggiungono la piena indipendenza vari mesi dopo la nascita, tra la fine di agosto e ottobre[11][21]. La maturità sessuale viene raggiunta a un anno di età[11].
La dispersione dei giovani furetti avviene tra gli inizi di settembre e i primi di novembre. Le distanze coperte possono essere brevi o lunghe. Nei pressi di Meeteetse (Wyoming) 9 giovani maschi e 3 giovani femmine si allontanarono di 1–7 km dopo aver abbandonato la tana materna. Quattro giovani femmine coprirono una breve distanza (meno di 300 m), ma rimasero entro i confini della propria area natale[21].
Fino al 91% della dieta del furetto dai piedi neri è costituito da cani della prateria[10][11]. La dieta, tuttavia, varia a seconda della distribuzione geografica. Nel Colorado occidentale, nello Utah, nel Wyoming e nel Montana, i furetti in passato si nutrivano quasi esclusivamente di cani della prateria dalla coda bianca ed erano costretti a cercare prede alternative quando questi ultimi andavano, per quattro mesi, in ibernazione[18]. Nel Wyoming, tra le prede alternative catturate durante il periodo di ibernazione dei cani della prateria dalla coda bianca figurano arvicole (genere Microtus) e topi (generi Peromyscus e Mus) catturati in prossimità dei torrenti. Nel South Dakota, i furetti si nutrono soprattutto di cani della prateria dalla coda nera. Poiché questi ultimi non vanno in ibernazione, la dieta dei furetti presenti nell'area subisce solamente piccole variazioni stagionali[9][18].
Nella Contea di Mellette (South Dakota), resti di cani della prateria dalla coda nera sono stati rinvenuti nel 91% degli 82 escrementi di furetto analizzati. Resti di topi erano presenti nel 26% delle deiezioni. Sulla base dei resti esaminati non è stato possibile individuare le specie di topo a cui tali resti appartenevano, ma nelle trappole posizionate nell'area sono stati catturati peromischi, topi cavalletta del nord e topi domestici. Tra le altre prede rinvenute figuravano inoltre citelli dalle tredici linee, gopher del Texas, silvilaghi di montagna, piro-piro codalunga, allodole golagialla e sturnelle allodola occidentali[11].
Nell'87% delle 86 deiezioni di furetto rinvenute nei pressi di Meeteetse (Wyoming) sono stati rinvenuti resti di cani della prateria dalla coda bianca. Assieme a questi vi erano resti di peromischi, arvicole delle artemisie, arvicole della Pennsylvania, silvilaghi di montagna e jack-rabbit dalla coda bianca. L'acqua necessaria viene ricavata dalle prede consumate[8].
Secondo uno studio pubblicato nel 1983 una femmina adulta di furetto dai piedi neri e i suoi piccoli necessitano ogni anno di circa 474-1.421 cani della prateria dalla coda nera o di 412-1.236 cani della prateria dalla coda bianca. I ricercatori che effettuarono questo studio giunsero alla conclusione che per proteggere adeguatamente la specie bisognerebbe proteggere 37-95 ettari di areale di cane della prateria dalla coda nera o 167-355 ettari di areale di cane della prateria dalla coda bianca per ogni femmina di furetto con i piccoli[23].
L'areale storico del furetto dai piedi neri era strettamente correlato, ma non ristretto, a quello dei cani della prateria (genere Cynomys). Esso si estendeva dalle regioni meridionali di Alberta e Saskatchewan fino a Texas, Nuovo Messico e Arizona[6]. Nel 1987, l'unica popolazione rimasta di furetti selvatici era stanziata in un'area di circa 2.428 ettari nella parte occidentale del Bighorn Basin, nei pressi di Meeteetse (Wyoming)[8][9][10][20][21]. A partire dal 1990, i furetti sono stati reintrodotti nelle seguenti aree: Shirley Basin (Wyoming); Rifugio Nazionale di UL Bend e Riserva Indiana di Fort Belknap (Montana); Parco nazionale delle Badlands, Prateria Nazionale del Buffalo Gap e Riserva Indiana di Cheyenne River (Dakota del Sud); Aubrey Valley (Arizona); Wolf Creek (Colorado); Coyote Basin (tra Colorado e Utah); Contea di Logan (Kansas); e Chihuahua settentrionale (Messico)[22].
Tra gli habitat storici del furetto vi erano praterie di erba bassa, praterie miste, praterie desertiche, steppe arbustive, steppe di artemisia[21], praterie montane e praterie semi-desertiche[6]. I furetti utilizzano le tane dei cani della prateria per allevare i piccoli, evitare i predatori e ripararsi dai rigori del clima[8][11]. Sei covi di furetto situati nei pressi della Contea di Mellette (South Dakota), erano foderati con fili d'erba di Bouteloua dactyloides, Aristida oligantha, Vulpia octoflora e Bromus tectorum. Densità elevate di gallerie di cani della prateria forniscono la maggior quantità di ripari ai furetti[8][9]. Le colonie dei cani della prateria dalla coda nera contengono una maggiore densità di gallerie per ettaro di quelle dei cani della prateria dalla coda bianca, e sono quindi maggiormente indicate per il recupero dei furetti[8]. Per i furetti è importante anche il tipo di galleria che viene occupato. Le cucciolate di furetto nei pressi di Meeteetse (Wyoming) erano situate in prossimità delle collinette di ingresso delle gallerie dei cani della prateria dalla coda bianca. Le collinette di ingresso contengono più entrate e probabilmente offrono un sistema di gallerie più esteso e profondo per la protezione dei piccoli[8]. Tuttavia, nello stesso sito, i furetti utilizzano con più frequenza le gallerie prive di collinette (64%) di quelle fornite di questi ingressi (30%)[9].
Tra le principali cause di mortalità dei furetti vi sono la perdita dell'habitat, le malattie introdotte dall'uomo e gli avvelenamenti indiretti legati al controllo dei cani della prateria[11][18][20][22]. La mortalità annuale di esemplari giovani e adulti a Meeteetse (Wyoming) in un periodo di 4 anni risultò essere del 59-83% (128 esemplari)[21]. Durante l'autunno e l'inverno morì il 50-70% dei giovani e degli esemplari più vecchi[21]. La speranza di vita media in natura è probabilmente di un unico anno, ma può raggiungere anche i 5 anni. Il tasso di mortalità tra i maschi è maggiore che nelle femmine, poiché questi, disperdendosi su distanze maggiori, sono più vulnerabili agli attacchi dei predatori[21].
Data la loro stretta dipendenza dai cani della prateria, i furetti sono estremamente vulnerabili ai danni arrecati alle loro colonie dall'agricoltura, dal bestiame e da altre attività antropiche[22].
I furetti sono soggetti a numerose malattie. Tra di esse la più letale è il cimurro canino (Morbillivirus)[6][21], trasmesso da moffette striate, procioni comuni, volpi rosse, coyote e tassi americani[20]. Per gli esemplari che crescono in cattività è disponibile un vaccino a breve termine contro il cimurro, ma per gli esemplari che nascono in natura non vi è alcuna protezione. Tra le altre malattie che colpiscono i furetti ricordiamo la rabbia, la tularemia e l'influenza umana. La peste selvatica (Yersinia pestis) probabilmente non colpisce direttamente i furetti, ma può distruggere intere colonie di cani della prateria, loro preda principale[21].
I furetti possono cadere vittima di aquile reali, gufi della Virginia, coyote, tassi americani, linci rosse, falchi della prateria, poiane tabaccate e crotali della prateria[11][20][21].
I processi di esplorazione ed estrazione di petrolio e gas naturale possono avere effetti deleteri sia per i cani della prateria che per i furetti. Le attività sismiche fanno crollare le gallerie dei cani della prateria. Tra gli altri fattori di minaccia ricordiamo potenziali perdite e sversamenti di greggio, l'aumento di strade e recinzioni, l'incremento dei veicoli e della presenza umana, e l'aumento degli uccelli rapaci, che trovano ottimi posatoi nei tralicci dell'alta tensione. Inoltre, i furetti possono rimanere feriti nelle trappole posizionate per catturare coyote, visoni americani e altri animali[10].
Presso alcune tribù di nativi americani, come i Crow, i Piedi Neri, i Sioux, i Cheyenne e i Pawnee, i furetti dai piedi neri giocavano un ruolo importante nei riti religiosi e nella dieta[18]. Nessun esemplare appartenente a questa specie venne avvistato durante la spedizione di Lewis e Clark, né venne mai scorto da Nuttall o Townsend, ed essa divenne nota al mondo scientifico solamente nel 1851, quando venne descritta per la prima volta da Audubon e Bachman in Viviparous Quadrupeds of North America[24]:
«È con grande piacere che vi presentiamo questa nuova e bella specie; ... [essa] abita le regioni boschive del Paese fino alle Montagne Rocciose, e forse è presente anche al di là di questa catena... Se poniamo mente alla rapidità con la quale ogni spedizione finora effettuata ha attraversato le Montagne Rocciose, non bisogna meravigliarsi se molte specie sono state del tutto trascurate... Le abitudini di questa specie ricordano, almeno da quanto abbiamo potuto apprendere, quelle della puzzola europea. Si nutre di uccelli, piccoli rettili e animali, uova e insetti vari, ed è un nemico audace e astuto di conigli, lepri, tetraoni, e altri animali da preda delle nostre regioni occidentali.»
(Audubon e Bachman, 1851[24])Per un certo periodo di tempo, i furetti dai piedi neri vennero cacciati per la loro pelliccia, e verso la fine degli anni '30 del XIX secolo la American Fur Company ne ricevette 86 pelli provenienti da Pratt, Chouteau e dalla Compagnia di St. Louis. Durante i primi anni del programma di controllo dei predatori, le carcasse dei furetti rimasti uccisi venivano probabilmente scartate, dato lo scarso valore della loro pelliccia. Tale situazione è probabilmente continuata anche dopo l'approvazione dello Endangered Species Act del 1973, per paura di rappresaglie. Il grave declino della popolazione dei furetti ha avuto inizio nel XIX secolo e si è protratto nel XX, in seguito alla diminuzione dei cani della prateria dovuta ai programmi di controllo e alla conversione delle praterie in terreni agricoli. Anche la peste selvatica, una malattia causata da Yersinia pestis, un agente patogeno introdotto accidentalmente in Nordamerica, ha contribuito alla decimazione dei cani della prateria, ma dal momento che il numero dei furetti è diminuito molto di più rispetto a quello delle loro prede, è probabile che alla loro scomparsa abbiano influito anche altri fattori. La peste è stata individuata per la prima volta in South Dakota in un coyote nel 2004, e successivamente, nel 2005, in un'area popolata da cani della prateria vasta circa 20.000 ettari nella Riserva di Pine Ridge. Tuttavia, nel 2006-07, 2.800 ettari di colonie di cani della prateria sono stati trattati con insetticida (DeltaDust®) e 400 ettari di habitat dei furetti nel Conata Basin sono stati cosparsi di insetticida a scopo di profilassi. Ciononostante, nel maggio del 2008 la peste è stata individuata anche nei furetti. Da allora, ogni anno 4.800 ettari del Conata Basin vengono trattati con insetticida e circa 50-150 furetti sono stati vaccinati contro la peste[25]. Alla decimazione della specie potrebbe aver contribuito anche la depressione da inincrocio, dal momento che studi effettuati a Meeteetse (Wyoming) hanno rivelato bassi livelli di variabilità genetica. Nel 1985 la popolazione ivi presente venne devastata dal cimurro canino. La specie è estremamente suscettibile a quest'ultima malattia, come sta a indicare il fatto che molti esemplari sono morti dopo essere stati trattati con un vaccino con virus attenuato originariamente prodotto per i furetti domestici[16].
Il furetto dai piedi neri è una di quelle specie che deve la propria sopravvivenza ai programmi di riproduzione in cattività[26]. Un primo programma di allevamento in cattività ebbe inizio nel 1987, con la cattura di 18 esemplari selvatici e l'impiego dell'inseminazione artificiale. Questa fu una delle prime volte in cui degli studiosi hanno cercato di salvare una specie in pericolo con la riproduzione assistita[26]. Successivamente, a partire dal 1991, il Servizio Pesca e Fauna Selvatica degli Stati Uniti (USFWS), varie agenzie statali e tribali, proprietari terrieri privati, gruppi conservazionisti e zoo nordamericani hanno iniziato a reintrodurre i furetti in natura, inizialmente nella Prateria Nazionale del Thunder Basin (Wyoming orientale), e successivamente in Montana, South Dakota (in sei siti nel 1994), Arizona, Utah, Colorado, Saskatchewan, Canada e Chihuahua (Messico). Allo Zoo di Toronto sono nati centinaia di esemplari, quasi tutti rilasciati in natura[27]. Alcuni episodi della serie di documentari Zoo Diaries mostrano appunto alcuni momenti di questa riproduzione controllata. Nel maggio del 2000, il Canadian Species at Risk Act inserì il furetto dai piedi neri tra le specie scomparse dal suolo nazionale[28]. Il 2 ottobre del 2009, tuttavia, una popolazione composta da 34 esemplari è stata rilasciata nel Parco Nazionale delle Grasslands (Saskatchewan meridionale)[29] e già nel luglio del 2010 è stata osservata nell'area una cucciolata[30]. I furetti reintrodotti in natura si sono quasi sempre riprodotti in tutti i siti di reintroduzione.
Il furetto dai piedi neri è classificato come Endangered, «in pericolo», dall'Endangered Species Act dal 20 settembre del 2005. Nel settembre del 2006 la popolazione di furetti del South Dakota venne stimata attorno ai 420 esemplari, dei quali 250 (100 adulti riproduttori costituiti da 67 femmine e 33 maschi) nella zona di Eagle Butte, in un'area vasta 40.468 ettari (meno del 3% del suolo pubblico costituito da praterie del South Dakota), 112 km ad est di Rapid City nella Prateria Nazionale del Buffalo Gap confinante con il Parco nazionale delle Badlands; 130 a nord-est di Eagle Butte, nella Riserva Indiana di Cheyenne River; e circa 40 nella Riserva Indiana di Rosebud[31]. La popolazione di furetti reintrodotta nella Aubrey Valley, in Arizona, supera già i 100 esemplari, mentre un secondo sito di reintroduzione ospita circa 50 esemplari. Secondo un rapporto pubblicato sulla rivista Science nell'agosto del 2007, in un'area del Wyoming vi erano 223 furetti (il numero originario di furetti reintrodotti, molti dei quali morti poco dopo, era di 228 capi), che nel periodo 2003-2006 avevano registrato un tasso di crescita annuale del 35%[32][33]. Questo tasso di recupero è molto più rapido di quello riscontrato in molte specie minacciate, e sembrerebbe che i furetti siano riusciti a superare i precedenti problemi legati alle malattie e alla carenza di prede che avevano ostacolato il loro recupero[33]. Nel 2007, il numero totale di furetti dai piedi neri presenti allo stato selvatico negli Stati Uniti superava i 650 esemplari, ed altri 250 individui erano presenti in cattività. Nel 2008, la IUCN riclassificò la specie come Endangered, «in pericolo»: un sostanziale miglioramento rispetto al 1996, quando era stata dichiarata «estinta in natura», dal momento che all'epoca tutti gli esemplari rimasti vivevano in cattività.
Nel 2013 il numero di furetti dai piedi neri presenti in natura è stato stimato a circa 1.200 capi[34].
I programmi di conservazione sono stati accolti in malo modo dagli allevatori di bestiame e dagli agricoltori, che combattono da decenni contro i cani della prateria. Nel 2005, il Servizio delle Foreste degli Stati Uniti iniziò a effettuare un programma di avvelenamento di cani della prateria sui terreni privati del Conata Basin confinanti con la Prateria Nazionale del Buffalo Gap (South Dakota). Dato che 10-15 allevatori reputarono inadeguate le misure prese, il Servizio Forestale, su consiglio di Mark Rey, all'epoca Sottosegretario dell'Agricultura, nel settembre del 2006 estese il «trattamento» all'intera Prateria Nazionale del Buffalo Gap e a quella di Fort Pierre, nonché a quella degli Oglala, nel Nebraska, malgrado il parere contrario dei biologi del Servizio Pesca e Fauna Selvatica degli Stati Uniti. Tuttavia, in seguito alle proteste portate avanti da gruppi di conservazionisti come la Climate, Community & Biodiversity Alliance, dai media nazionali[35], dall'opinione pubblica e da alcuni ufficiali federali, il progetto di avvelenamento venne revocato.
La gestione contraddittoria delle due agenzie federali coinvolte, lo USFWS e il Servizio Forestale, può essere esemplificato da quanto sperimentato dalla tribù di Sioux stanziata nella Riserva di Rosebud. In quest'area lo USFWS introdusse una popolazione di furetti dopo aver stretto un accordo con i Sioux, ai quali venne promesso un risarcimento di oltre un milione di dollari all'anno fino al 2010. Dall'altra parte la tribù si era anche impegnata con il Servizio Forestale per un programma di avvelenamento dei cani della prateria. Il numero crescente dei furetti presenti nell'area portò ben presto a conflitti tra il Dipartimento di Caccia, Pesca e Parchi della tribù e l'Organizzazione Aziendale delle Terre Tribali. Quando il governo federale avviò un'indagine sul programma di gestione dei cani della prateria portato avanti dalla tribù, minacciando di perseguire i dipendenti tribali o gli agenti che stavano avvelenando i cani della prateria presenti nel sito di riproduzione dei furetti, il consiglio tribale, nel 2008, approvò una risoluzione chiedendo alle due agenzie federali di rimuovere i furetti e di rimborsare la tribù per le spese che erano state necessarie per il programma di recupero[36].
Nella versione italiana della seconda stagione de I segreti di Twin Peaks (negli episodi 23 e 24 oppure 16 e 17 nella numerazione italiana) si cita la Mustela nigripes come un piccolo mammifero in rischio d'estinzione che vivrebbe nella Foresta di Ghostwood, nei dintorni della cittadina di Twin Peaks, tra lo stato di Washington e il Canada. In realtà la Mustela nigripes non vive nella zona dov'è ambientata la serie e nella versione originale si fa riferimento a una non ben identificata pine weasel (‘donnola dei pini’) e Benjamin Horne mostra un disegno di un mustelide con la scritta Mustela pinus, nome binomiale inesistente.
Il furetto dai piedi neri (Mustela nigripes Audubon e Bachman, 1851), conosciuto nei luoghi d'origine anche come American polecat («puzzola americana») o prairie dog hunter («cacciatore di cani della prateria»), è un Mustelide originario delle regioni centrali del Nordamerica. Dal momento che ne rimangono solamente popolazioni piccole e poco numerose, viene classificato come specie in pericolo dalla IUCN.
Scoperta per la prima volta da Audubon e Bachman nel 1851, questa specie si è ridotta sempre più nel corso del XX secolo, prevalentemente a causa della diminuzione delle popolazioni di cani della prateria e delle epidemie di peste selvatica. Nel 1979 venne addirittura dichiarata estinta, fino a quando, nel 1981, il cane di Lucille Hogg non si presentò alla porta dell'abitazione di Meeteetse (Wyoming) con un furetto morto in bocca. Le poche dozzine di esemplari rimasti continuarono a vivere nell'area fino a quando la specie non venne dichiarata estinta in natura nel 1987. Tuttavia, grazie ad un programma di riproduzione in cattività condotto dal Servizio Pesca e Fauna Selvatica degli Stati Uniti, tra il 1991 e il 2008 alcuni furetti sono stati reintrodotti in otto stati occidentali e in Messico. Attualmente in natura vi sono più di 1.000 esemplari adulti nati allo stato selvatico, suddivisi in 18 popolazioni, delle quali quattro autosufficienti in Dakota del Sud (due), Arizona e Wyoming.
Il furetto dai piedi neri ha all'incirca le dimensioni di un visone, e si differenzia dalla puzzola europea per il maggiore contrasto tra la colorazione scura delle zampe e quella chiara del corpo e per la minore lunghezza della coda, nera all'estremità. Al contrario, le differenze intercorrenti tra il furetto dai piedi neri e la puzzola delle steppe dell'Asia sono esigue, al punto che in passato i due erano considerati conspecifici. Infatti, il furetto si distingue da quest'ultima solamente per avere manto più breve e ispido, orecchie più grandi ed estensione post-molare del palato più lunga.
Conduce prevalentemente vita notturna e solitaria, tranne che nel periodo riproduttivo e dell'allevamento dei piccoli. Fino al 91% della sua dieta è composta da cani della prateria.
Melnkāju sesks jeb Amerikas sesks (Mustela nigripes) ir neliels sermuļu dzimtas (Mustelidae) plēsējs.
Dzīvo Ziemeļamerikā. Tā tuvākais radinieks ir stepes sesks (Mustela eversmanii), kas dzīvo Krievijas stepēs.[1] Bieži melnkāju sesku jauc ar mājas sesku, bet tie nav tik tuvi radinieki, lai gan abi pieder sermuļu ģintij.
Melnkāju sesks ir apdraudēta suga, un to sargā likums. Kopš 1937. gada tas vairs nedzīvo Kanādā, un kopš 1967. gada tas ir ierakstīts ASV Sarkanajā grāmatā, bet kopš 1979. gada pastāvēja uzskats, ka melnkāju sesks visā Ziemeļamerikā ir izmiris.[2] Par pārsteigumu dabas pētniekiem Vaiomingā tika atklāta neliela sesku populācija. Pēdējo savvaļas populāciju 1986. gadā sagūstīja un turpināja audzēt nebrīvē. Nebrīvē dzimušos melnkāju seskus kopš tā laika veiksmīgi introducē dažādās seska vēsturiskajās dzīves vietās, un šis projekts ir kļuvis par brīnišķīgu piemēru tam, kā var dabā atgriezt gandrīz izmirušu sugu.[3]
Melnkāju seska ķermenis ir garš, slaids un lokans, tam ir īsas kājas un saplacināta galvas forma ar trīsstūrveida seju. Ausis mazas un noapaļotas. Ķermenis bez astes ir apmēram 45 cm garš, bet kuplā aste ir 15 cm gara, svars apmēram 1 kg. Kažoka matojuma spalviņas pie pamatnes ir baltas, bet kļūst tumšākas spalvas galā, radot kopējo bālganbrūno izskatu. Mugura ir tumšāka par pavēderi un pakakli. Tā kājas, astes gals un sejas maska ir melna.
Melnkāju sesks ir nakts dzīvnieks, un tā galvenais medījums ir prēriju suņi. Tas retu reizi medī arī citus mazus zīdītājus, putnus un kukaiņus. Gada laikā melnkāju sesks apēd apmēram 100 prēriju suņus, un, ja tā dzīves vietas tuvumā nav liela kolonija ar šiem mazajiem dzīvnieciņiem, tad sesks nevar izdzīvot. Viena prēriju suņu kolonija aizņem apmēram 50 ha platības, kas nodrošina viena pieauguša melnkāju seska vajadzības pēc barības. Melnkāju seska izdzīvošana ir cieši saistīta ar prēriju suņiem. Sesks pat migu iekārto prēriju suņu alās. Dažreiz sesks nomedī kādu peli.
Riests melnkāju seskiem sākas martā, aprīlī. Grūsnība ilgst 41—45 dienas. Piedzimst 1—7 mazuļi, bet vidēji 3—4 mazuļi.
Melnkāju seski 19. un 20. gadsimtā gandrīz izmira, jo kritiski samazinājās prēriju platības, izplešoties lauksaimniecībai, kas savukārt samazināja prēriju suņu populāciju, un sesku populācijā izplatījās vairākas smagas slimības, kā suņu mēris un meža mēris, kas ir līdzīgs buboņu mērim. Arī pirms tam melnkāju sesks nebija bieži sastopams dzīvnieks. To kā atsevišķu sugu klasificēja tikai 1851. gadā dabas pētnieki J.J.Adabons (John James Audubon) un R.J.Bačmens (Rev. John Bachman). Jau 19. gadsimta vidū melnkāju seskiem draudēja izmiršana, jo saskaņā ar šo pētnieku novērojumiem dabā, sesks netika pamanīts un datēts vairāk kā 20 gadus.
Ļoti mazu melnkāju sesku populāciju, kurā bija 130 dzīvnieki, nejauši atklāja 1981. gadā Vaiomingā. Drīz pēc tam populācija strauji izmira slimību dēļ. Dabas pētnieki no Vaiomingas 1986. gadā uzsāka melnkāju sesku glābšanas projektu un saķēra pēdējos 18 seskus, lai drošos apstākļos, nebrīvē pavairotu melnkāju sesku populāciju. Šajā laikā melnkāju seski dzīvoja vairs tikai nebrīvē dažādos zoodārzos, īpatņu kopējais skaits bija apmēram 50.
Kopš 1991. gada melnkāju seskus sāka introducēt atpakaļ savvaļā. Šie dzīvnieki ir atgriezušies Montānas, Dienviddakotas, Arizonas, Jūtas, Kolorādo un Čihuahua Meksikā dabas ainavās. Toronto zoodārzs ir izaudzējis vairākus simtus melnkāju sesku un introducējis tos Kanādas dabā,[2] lai gan sesks joprojām arī 2000. gada dzīvnieku uzskaitē Kanādā skaitās izmiris.[4]
2007. gadā melnkāju sesku populācija ASV bija sasniegusi vairāk kā 750 dzīvnieku, bet zoodārzos dzīvoja 250 seski, par spīti tam, ka 1996. gadā dzīvnieks tika pasludināts par izmirušu ASV.[5]
Melnkāju sesks jeb Amerikas sesks (Mustela nigripes) ir neliels sermuļu dzimtas (Mustelidae) plēsējs.
Dzīvo Ziemeļamerikā. Tā tuvākais radinieks ir stepes sesks (Mustela eversmanii), kas dzīvo Krievijas stepēs. Bieži melnkāju sesku jauc ar mājas sesku, bet tie nav tik tuvi radinieki, lai gan abi pieder sermuļu ģintij.
Melnkāju sesks ir apdraudēta suga, un to sargā likums. Kopš 1937. gada tas vairs nedzīvo Kanādā, un kopš 1967. gada tas ir ierakstīts ASV Sarkanajā grāmatā, bet kopš 1979. gada pastāvēja uzskats, ka melnkāju sesks visā Ziemeļamerikā ir izmiris. Par pārsteigumu dabas pētniekiem Vaiomingā tika atklāta neliela sesku populācija. Pēdējo savvaļas populāciju 1986. gadā sagūstīja un turpināja audzēt nebrīvē. Nebrīvē dzimušos melnkāju seskus kopš tā laika veiksmīgi introducē dažādās seska vēsturiskajās dzīves vietās, un šis projekts ir kļuvis par brīnišķīgu piemēru tam, kā var dabā atgriezt gandrīz izmirušu sugu.
De zwartvoetbunzing (Mustela nigripes) is een marterachtige uit Noord-Amerika. Vroeger kwamen ze voor op de gehele Noord-Amerikaanse prairies, maar de soort was in de 20ste eeuw nagenoeg uitgestorven in het wild. Wetenschappers vingen in 1981 de laatst bekende populatie in een (succesvolle) poging deze soort te redden. Sinds 1991 worden dieren weer gecontroleerd vrijgelaten, waardoor hun aantal fors gestegen is.
De zwartvoetbunzing wordt 38 tot 41 centimeter lang en weegt 900 tot 1000 gram. De staart is 11 tot 13 centimeter lang.
De zwartvoetbunzing leeft voornamelijk solitair. Hij jaagt de prairiehonden tot in hun hol na. De zwartvoetbunzing bouwt ook zijn nest in het hol van een prairiehond. Per worp krijgt de bunzing drie tot zes jongen.
De jacht op zijn voornaamste prooidier, de prairiehonden, zorgde ervoor dat de zwartvoetbunzing in het wild was uitgestorven. Inmiddels zijn in gevangenschap gefokte prairiehonden en zwartvoetbunzings uitgezet op zeven plaatsen in Wyoming.[2]
In 2007 waren er weer 220 zwartvoetbunzings in het wild. De populatie groeit met 35 % per jaar.[3] In 2011 waren er zo'n 1000 exemplaren.[2] Verder leven er nog zo'n 250 exemplaren in gevangenschap.[4]
Mediabestanden die bij dit onderwerp horen, zijn te vinden op de pagina Mustela nigripes op Wikimedia Commons. De zwartvoetbunzing (Mustela nigripes) is een marterachtige uit Noord-Amerika. Vroeger kwamen ze voor op de gehele Noord-Amerikaanse prairies, maar de soort was in de 20ste eeuw nagenoeg uitgestorven in het wild. Wetenschappers vingen in 1981 de laatst bekende populatie in een (succesvolle) poging deze soort te redden. Sinds 1991 worden dieren weer gecontroleerd vrijgelaten, waardoor hun aantal fors gestegen is.
Svartfotilder (Mustela nigripes) er et rovdyr i mårfamilien.
Den ligner på og nedstammer fra den eurasiske steppeilderen (Mustela eversmanii) som innvandret til Nord-Amerika over Beringlandbrua i pleistocen. Kroppslengden er 38–41 cm, og halen er 11–13 cm. Pelsen er gulaktig med mørk ansiktsmaske, halespiss og føtter. Kullene er på tre–fire unger.[2]
Svartfotilderen var utbredt på de tørre grasslettene på Great Plains i Nord-Amerika fra sørlige Canada til nordlige Mexico. Utbredelsen overlappet fullstendig med utbredelsen til det viktigste byttet, præriehunder (Cynomys). For en kortere tid ble den gjenstand for pelsjakt, med American Fur Company som avtager, men ettersom pelsen ikke nådde opp i kvalitet falt denne jakten bort.
Utryddelseskampanjer rettet mot præriehunder førte til at svartfotilderen døde ut i vill tilstand i siste del av 1980-årene. Fra 1991 har en forsøkt å gjeninnføre arten ved utsettinger, og det var i 2015 omtrent 500 frittlevende eksemplarer i USA og Mexico.[1]
Svartfotilder (Mustela nigripes) er et rovdyr i mårfamilien.
Den ligner på og nedstammer fra den eurasiske steppeilderen (Mustela eversmanii) som innvandret til Nord-Amerika over Beringlandbrua i pleistocen. Kroppslengden er 38–41 cm, og halen er 11–13 cm. Pelsen er gulaktig med mørk ansiktsmaske, halespiss og føtter. Kullene er på tre–fire unger.
Svartfotilderen var utbredt på de tørre grasslettene på Great Plains i Nord-Amerika fra sørlige Canada til nordlige Mexico. Utbredelsen overlappet fullstendig med utbredelsen til det viktigste byttet, præriehunder (Cynomys). For en kortere tid ble den gjenstand for pelsjakt, med American Fur Company som avtager, men ettersom pelsen ikke nådde opp i kvalitet falt denne jakten bort.
Utryddelseskampanjer rettet mot præriehunder førte til at svartfotilderen døde ut i vill tilstand i siste del av 1980-årene. Fra 1991 har en forsøkt å gjeninnføre arten ved utsettinger, og det var i 2015 omtrent 500 frittlevende eksemplarer i USA og Mexico.
Multimedia w Wikimedia Commons Tchórz czarnołapy, tchórz czarnonogi (Mustela nigripes) – gatunek drapieżnego ssaka z rodziny łasicowatych (Mustelidae).
Środkowa część Ameryki Północnej[3] - od południowej Kanady po północny Meksyk. Od 1965 uznawany za gatunek zagrożony wyginięciem, a od 1996 wymarły w stanie dzikim (m.in. wskutek odstrzału piesków preriowych, na które poluje). W Kanadzie wyginęły już w 1937. Ostatnie dziko żyjące populacje obserwowano w latach 80. XX w. Populacja znaleziona w 1981 w Meeteetse została przetrzebiona chorobami. W 1987 doliczono się ostatnich 18 osobników trzymanych w niewoli w stanie Wyoming.[4] Od tamtej pory podejmowane są działania zmierzające do reintrodukcji gatunku.[5] Jedno z nich okazało się skuteczne – liczba żyjących na wolności osobników przekroczyła 223 w 2006 r. [6]
Osiąga 45-60 cm długości wraz z ogonem oraz ok. 1 kg masy ciała. Samce są nieznacznie większe od samic. Tchórz czarnołapy poluje na pieski preriowe, które są podstawą jego diety. Zjada również myszy i inne gryzonie. Prowadzi nocny tryb życia. Samica w jednym miocie rodzi od 1-6 młodych. Poza okresem rozrodu żyją samotnie.
Tchórz czarnonogi jest objęty konwencją CITES.
Tchórz czarnołapy, tchórz czarnonogi (Mustela nigripes) – gatunek drapieżnego ssaka z rodziny łasicowatych (Mustelidae).
A doninha-de-patas-pretas[2] (Mustela nigripes), também conhecida como toirão-americano[3] ou furão-do-pé-preto,[4] é uma espécie de mustelídeo nativa do centro de América do Norte. Está listada como em perigo pela IUCN por ocorrer em populações restritas e diminutas. Descoberta pela primeira vez por Audubon e Bachman em 1851, a espécie entrou em declíneo populacional ao longo do século XX em resultado da diminuição drástica da população de cães-da-pradaria e devido à peste silvestre.[5]
Foi declarada extinta em 1979 até que um cão de uma família de criadores de gado, John e Lucille Hogg lhes levou um espécime morto para a sua porta, em Meeteetse, Wyoming em 1981.[6] A restante e diminuta população manteve-se até 1987, quando estes animais foram considerados como Espécie extinta na natureza. Contudo, através de um programa de procriação em cativeiro da responsabilidade do United States Fish and Wildlife Service, foi possível a sua reintrodução em oito estados e no México, de 1991 a 2008.
Existem atualmente cerca de 1000 indivíduos adultos nascidos em estado selvagem, perfazendo cerca de 18 populações, com quatro populações auto-sustentadas no Dakota do Sul (duas), Arizona e Wyoming.[1][7]
Em 2020, uma equipa de cientistas clonou uma doninha-de-patas-pretas chamada Elizabeth Ann a partir das células congeladas de um ancestral numa conquista histórica que impulsiona os esforços de conservação. Elizabeth Ann foi criada a partir das células de Willa, outra doninha-de-patas-pretas que viveu há mais de 30 anos[8].
A doninha-de-patas-pretas (Mustela nigripes), também conhecida como toirão-americano ou furão-do-pé-preto, é uma espécie de mustelídeo nativa do centro de América do Norte. Está listada como em perigo pela IUCN por ocorrer em populações restritas e diminutas. Descoberta pela primeira vez por Audubon e Bachman em 1851, a espécie entrou em declíneo populacional ao longo do século XX em resultado da diminuição drástica da população de cães-da-pradaria e devido à peste silvestre.
Foi declarada extinta em 1979 até que um cão de uma família de criadores de gado, John e Lucille Hogg lhes levou um espécime morto para a sua porta, em Meeteetse, Wyoming em 1981. A restante e diminuta população manteve-se até 1987, quando estes animais foram considerados como Espécie extinta na natureza. Contudo, através de um programa de procriação em cativeiro da responsabilidade do United States Fish and Wildlife Service, foi possível a sua reintrodução em oito estados e no México, de 1991 a 2008.
Existem atualmente cerca de 1000 indivíduos adultos nascidos em estado selvagem, perfazendo cerca de 18 populações, com quatro populações auto-sustentadas no Dakota do Sul (duas), Arizona e Wyoming.
Em 2020, uma equipa de cientistas clonou uma doninha-de-patas-pretas chamada Elizabeth Ann a partir das células congeladas de um ancestral numa conquista histórica que impulsiona os esforços de conservação. Elizabeth Ann foi criada a partir das células de Willa, outra doninha-de-patas-pretas que viveu há mais de 30 anos.
Svartfotad iller (Mustela nigripes) är en art i familjen mårddjur som förekommer i Nordamerika. Arten blev under 1900-talet nästan utrotad och kategoriserades 1970 som utdöd. 1981 lokaliserades en mindre koloni nära Meeteetse i Wyoming som utgör ursprunget till dagens population.
Artepitet i det vetenskapliga namnet är sammansatt av de latinska orden niger (svart) och pes (fot).[2]
Svartfotad iller har som många arter i samma släkte en långsträckt kropp och korta extremiteter. Framtassarna är jämförelsevis stora med kraftiga klor för att gräva i marken.[3] Pälsen är huvudsakligen gulbrun och vid huvudet vit med en svart mask runt ögonen. Även nedre delen av benen och svanstippen är svarta. Kroppslängden (huvud och bål) ligger mellan 38 och 60 cm och vikten mellan 0,65 och 0,85kg för honor respektive mellan 0,9 och 1,1 kg. Hanar är i genomsnitt 10 % större än honor.[4] Svansen blir 11 till 15 cm lång.[3]
Utbredningsområdet för den svartfotade illern var ursprungligen prärien i mellersta Nordamerika, och sträckte sig från Alberta och Saskatchewan till Arizona och Texas. Idag finns mindre populationer i Montana, South Dakota, Wyoming och Arizona.[4] Dessa djur avlades fram ur en mindre grupp från Wyoming och sedan återintroducerade (se mer nedan).
Den svartfotade illern är beroende av präriehundar både som byte och eftersom den använder deras gryt som viloplats. Den jagar under skymningen och natten och vilar under dagen i sitt gryt. Svartfotad iller lever ensam och försvarar sitt revir mot artfränder av samma kön. Nästan 90% av dess föda utgörs av präriehundar. De äter även andra mindre däggdjur som ekorrar och möss.[4] Under kalla årstider blir individerna slö och de kan stanna upp till en vecka i boet.[4] Reviret är vanligen 40 till 60 hektar stort.[3]
Efter parningstiden som ligger i mars och april och dräktigheten som går över 42 till 45 dagar föder honan en till sex (i genomsnitt tre) ungar. De befruktade äggen vilar en tid innan den egentliga dräktigheten börjar.[4] Ungarna är vid födelsen hjälplös, blinda och kroppen är täckt med korta vita hår. Efter cirka 42 dagar syns de för första gången utanför grytet.[3] Under hösten skiljer sig ungdjuren från sin mor och efter ungefär ett år är de könsmogna.[4] Medellivslängden i fångenskap ligger vid tolv år.[4]
Vissa auktoriteter menar att svartfotad iller utgör samma art som Mustela eversmanii.[1]
Fram till början av 1900-talet var svartfotad iller vanlig i Nordamerika. Men arten minskade på grund av den omfattande utrotningen av präriehund, som betraktades som skadedjur. Redan under 1960-talet var arten mycket sällsynt och under 1970-talet betraktades den som utdöd. 1981 hittades en tidigare okänd koloni i Meeteetse i Wyoming. Arton individer infångades under perioden 1985-1987 vilka utgjorde grunden i ett avelsprogram för att skapa ett större bestånd.[1] 1987 inträffade en epidemi bland präriehundar vilket minskade den vilda populationen än mer.[1] Men avelsprogrammet var framgångsrikt och 1991 återintroducerade de första illrarna i Wyoming. Allt som allt har 18 populationer återintroducerade i USA och i Mexiko, varav tre inte behöver vidare individförstärkning från avelsprogrammet.[1] Det finns idag ingen känd ickeintroducerad population i det vilda och endast tre populationer har adulta individer som är födda i det vilda.[1] Det vilda beståndet uppskattades 2008 till maximalt 1000 individer.[1] Projektet avlar fram över 240 nya illrar varje år.[källa behövs]
Wikimedia Commons har media som rör Svartfotad iller.
Svartfotad iller (Mustela nigripes) är en art i familjen mårddjur som förekommer i Nordamerika. Arten blev under 1900-talet nästan utrotad och kategoriserades 1970 som utdöd. 1981 lokaliserades en mindre koloni nära Meeteetse i Wyoming som utgör ursprunget till dagens population.
Artepitet i det vetenskapliga namnet är sammansatt av de latinska orden niger (svart) och pes (fot).
Kara ayaklı gelincik (Mustela nigripes) Kuzey Amerika'ya özgü bir memeli hayvandır. Kara ayaklı gelincik, sansar, vizon, kokarca, gelincik, susamuru ve porsuklarla birlikte Sansargiller familyasında bulunur.
Kara ayaklı gelincik, nesli tehlikedeki türlerdendir. Günümüzde sadece ABD'de bulunurlar. Kanada'da soyları tükenmiştir. Bilinen son yabani gelincikler, 1980'lerde esaret altına alınmıştır ve doğal yaşam alanlarına geri salınmamışlardır. Şimdi doğada da başarılı bir şekilde üremektedirler.
Kara ayaklı gelincikler, kuyruğuyla birlikte 45 cm uzunluğunda, ve 1 kg ağırlığında olurlar. Diğer sansargillerin birçoğu gibi ince gövdeleri ve kısa bacakları vardır. Üst kısımları beyaz, alt kısımları sarımsı kahverengi ve ayakları ve yüzleri siyahtır.
Kara ayaklı gelincikler gece ortaya çıkarlar. Başlıca avları çayır köpekleridir. Ama küçük memelileri, kuşları ve böcekleri de yerler. Tek bir tanesi yılda 100 çayır köpeği avlayabilir ve onlar olmadan yaşayamazlar. Bir kara ayaklı gelinciğin yaşayabilmesi için yuvasının en fazla 50 hektar yakınında en az bir çayır köpeği kolonisi olması gerekir. Hatta bazen gelincikler terk edilmiş çayır köpeği yuvalarını kullanırlar. Gelinciklerin çiftleşme dönemi Mart ve Nisan aylarıdır. Yavruları genelde 41-43 günlük olunca üreme dönemine girerler. Çayır köpekleri 1 ila 7 yavru doğurabilirler ama genelde 3-4 yavru doğururlar.
Yaşadığı otlakların azalması, çayır köpeği nüfusunun azalması ve hastalıklar 19. ve 20. yüzyıllarda az daha bu türün neslini tüketiyordu. Hatta sayıları o kadar azaldı ki çok nadir görülmeye başlandılar. Hatta ve hatta, yaklaşık 20 yıl boyunca hiç görülmemeleri sebebiyle soylarının tükendiği varsayılmıştır.
1981 yılında, Wyoming'de sadece 130 hayvandan oluşan küçük bir koloni bulundu. Bu keşfin ardından hastalıklar nüfusunu çok azalttı. 1986 yılında, kalan 18 hayvan esaret altında üretilmeye başlandı. Az sonra, esaret altındaki nüfusları 50'ye yükseldi. 2007 yılında, yabani nüfusları 600'ü aştı. Bilim insanları bu üreme programıyla 2010 yılında kara ayaklı gelincik nüfusunun 1500 ulaşmasını, ve her kolonide en az 30 üreyen yetişkin olmasını umuyorlar.
Etçiller ile ilgili bu madde bir taslaktır. Madde içeriğini geliştirerek Vikipedi'ye katkıda bulunabilirsiniz. Голова і тіло довжиною 310—500 мм, хвіст завдовжки 110—150 мм. Самці на 10% більші за самиць і важать близько 1 кг, в той час як вага самиць становить близько 800 г.
Забарвлення тіла зазвичай жовто-буре, на череві світліше. Лоб, морда і горло майже білі. Верх голови і середина спини коричневі. Маска на обличчі, ступні й кінцева чверть хвоста чорні. Ноги короткі з відносно великими лапами, передні кінцівки озброєні великими кігтями, пристосованими для риття ґрунту. Має три пари молочних залоз.
Вид у першу чергу нічний і, як вважають, володіє гострим слухом, нюхом і зором. Сильно залежить від лучних собачок щодо їжі, але полонені з готовністю приймають інших малих ссавців. Чорноногі тхори ведуть усамітнений спосіб життя за винятком сезону розмноження, і самці не допомагають у вихованні молоді.
На чорноногих тхорів полюють койоти, беркути, віргінські пугачі (Bubo virgínianus), домашні коти і собаки.
У полоні спаровування відбувається в основному в березні-квітні, дітонародження — у травні-червні. Еструс тривав 32-12 днів, вагітність — 42-45 днів, народжувалося від 1 до 6, в середньому 3.0 дитинча. Молодь виходить з нір на початку липня і відокремлюється від матері у вересні або на початку жовтня. Молоді самці розходяться на значну відстань, а молоді самиці часто залишаються поблизу від материнської території. У неволі можуть дожити до 12-річного віку.
Первинний ареал чорноногого тхора простягався від Великих рівнин і канадської провінції Альберта до південного заходу США та Мексики. У 1987 році вид проголошено зниклим у природі. Завдяки заходам з реінтродукції чорноногий тхір знов мешкає у восьми західних штатах США та у мексиканському штаті Чиуауа, втім самодостатніми вважаються лише три популяції у штатах Вайомінг і Південна Дакота.
Мешкає на луках, у степах, помережаних чагарником, віддає перевагу ділянкам з травостоєм середньої висоти або низьким. Багато в чому залежить від лучного собачки, на якого полює і використовує його нори і щоб ховатись і ростити потомство. Одній особині для життя потрібна ділянка площею від 40 до 70 га.
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Chồn sương chân đen (danh pháp khoa học: Mustela nigripes) là một loài động vật có vú trong họ Chồn, bộ Ăn thịt. Loài này được Audubon & Bachman mô tả năm 1851.[2]
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Bài viết về các loài trong bộ thú ăn thịt này vẫn còn sơ khai. Bạn có thể giúp Wikipedia bằng cách mở rộng nội dung để bài được hoàn chỉnh hơn. Chồn sương chân đen (danh pháp khoa học: Mustela nigripes) là một loài động vật có vú trong họ Chồn, bộ Ăn thịt. Loài này được Audubon & Bachman mô tả năm 1851.
Федеральные и государственные агентства США в сотрудничестве с частными землевладельцами занимаются сохранением черноногого хорька в дикой природе через выпуск разведённых в неволе, зоопарках и научно-зоологические центрах, хорьков в их естественную среду обитания. Местами выпуска стали Штаты Монтана, Южная Дакота, Аризона, Юта, Колорадо и Чиуфуа Мексика.
В 1981 году было обнаружено маленькое поселение в 130 животных рядом с Meeteetse, Штат Вайоминг. Сразу после открытия этого поселения хорьков в связи с болезнью погибло более половины хорьков. Было принято решение для спасения судьбы черноногих хорьков отловить 18 особей разного пола и поместить их на территориях научно-зоологического центра.
По информации о состояние дел с черноногим хорьком в 2007 году, его число превышает 600 единиц в США. Хотя он ещё считается исчезающим видом по старой оценке 1996 года, так как в то время хорьки проживали только в неволе у группы специалистов.
План восстановления популяции хорька в его родной среде считает своей конечной задачей установление 10 или более отдельных самовыживающих диких поселений. Биологи надеются получить 1500 черноногих хорьков на свободе до 2010 года с не менее чем 30 воспроизводящими взрослыми особями в каждом поселении.
Федеральные и государственные агентства США в сотрудничестве с частными землевладельцами занимаются сохранением черноногого хорька в дикой природе через выпуск разведённых в неволе, зоопарках и научно-зоологические центрах, хорьков в их естественную среду обитания. Местами выпуска стали Штаты Монтана, Южная Дакота, Аризона, Юта, Колорадо и Чиуфуа Мексика.
В 1981 году было обнаружено маленькое поселение в 130 животных рядом с Meeteetse, Штат Вайоминг. Сразу после открытия этого поселения хорьков в связи с болезнью погибло более половины хорьков. Было принято решение для спасения судьбы черноногих хорьков отловить 18 особей разного пола и поместить их на территориях научно-зоологического центра.
По информации о состояние дел с черноногим хорьком в 2007 году, его число превышает 600 единиц в США. Хотя он ещё считается исчезающим видом по старой оценке 1996 года, так как в то время хорьки проживали только в неволе у группы специалистов.
План восстановления популяции хорька в его родной среде считает своей конечной задачей установление 10 или более отдельных самовыживающих диких поселений. Биологи надеются получить 1500 черноногих хорьков на свободе до 2010 года с не менее чем 30 воспроизводящими взрослыми особями в каждом поселении.
黑足鼬（学名：Mustela nigripes），是一種原產於北美洲的小型食肉性哺乳动物和唯一原產于北美地區的雪貂，亦是俄国草原臭鼬的近親。鼬科。同科物种有：黄鼬（黄鼠狼）、水貂、臭貂、貂屬和獾亞科。牠與被馴化的白鼬或矇眼貂外型非常相似，常被別人混淆。
黑足鼬是北美著名的濒危物种。
1937年，加拿大野生黑足鼬灭绝。1967年在美国被列为濒危物种。
2008年美國網站《生活科學》評出黑足鼬為全球十大最瀕危的稀有動物物種之一[1][永久失效連結]。
黑足鼬（学名：Mustela nigripes），是一種原產於北美洲的小型食肉性哺乳动物和唯一原產于北美地區的雪貂，亦是俄国草原臭鼬的近親。鼬科。同科物种有：黄鼬（黄鼠狼）、水貂、臭貂、貂屬和獾亞科。牠與被馴化的白鼬或矇眼貂外型非常相似，常被別人混淆。
黑足鼬是北美著名的濒危物种。
1937年，加拿大野生黑足鼬灭绝。1967年在美国被列为濒危物种。
검은발족제비(학명: Mustela nigripes)는 북아메리카 평원에 서식하는 족제비의 일종이다.[2] 검은발페릿이라고 불리기도 하나, 가축화된 페릿과는 다르다. 전염병과 환경 개발로 인한 서식지 상실로 인해 오래 전부터 수가 줄어왔으며, 캐나다에서는 1937년에 멸종되고 1967년 미국에서 보호종으로 지정되었다. 1986년에는 불과 18마리만이 잔존하는 것으로 파악되었으나, 그 후 수는 급등해 1,000마리로 증가했다.
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