Mountain goats communicate through vocalitizations during the mating season to attract mates. They display a high frequency of intraspecific aggression. Aggressive behaviors include present threat (a broadside orientation with apparent size enhancement by arching their backs), horn threat (aggressive movement and display of the horns), rush threat (a sudden quick movement toward the antagonist), and orientation threat (a lower intensity form of rush threat involving walking). All of these are examples of bluffing aggression, as individuals rarely suffer serious injuries.
Communication Channels: visual ; tactile
Other Communication Modes: scent marks
Perception Channels: visual ; tactile ; acoustic ; chemical
The native range of this species is from southeast Alaska to Washington, western Montana, and central Idaho. Mountain goats, Oreamnos americanus, are native to the northern Rocky Mountains. They have also been introduced to parts of South Dakota, Colorado, and Washington.
Biogeographic Regions: nearctic (Introduced , Native )
Although their diet varies throughout the year, it generally consists of grasses, woody plants, mosses, lichens, herbaceous plants, and other vegetation. They get most of their water from their food and year-round snowbanks. Mountain goats also travel many kilometers in the spring to mineral-rich salt licks.
Plant Foods: leaves; wood, bark, or stems; bryophytes; lichens
Primary Diet: herbivore (Folivore , Lignivore)
Ectoparasites that have been found on mountain goats are Dermacentor andersoni (a tick), and a chewing louse, Bovicola oreamnidis. Endoparasites that have been known to affect mountain goats are three species of cestodes: Moniezia benedeni, Thysanosoma actinioides, and Taenia hydatigena. Also 11 species of nematodes: Protostrongylus stilesi, Protostrongylus rushi (both were found on the lungs), Ostertagia circumcincta, O. ostertagi, O. trifurcata, Trichostrongylus colubriformis, Trichostrongylus axei, Nematodirus maculosus and N. helvetianus (the latter 2 found in the small intestines). Also tapeworms seem to be an endoparasite that have affected goats in South Dakota.
Ecosystem Impact: keystone species
Commensal/Parasitic Species:
Mountain goat hunting is very challenging due to the habitat the goats inhabit.
Positive Impacts: food ; body parts are source of valuable material
Mountain goats prefer steep, rocky areas with cliffs or bluffs in alpine or sub-alpine regions. They prefer areas with sufficient escape terrain (steep rocky areas), moderate slopes, mid-elevations, and southern exposures. They migrate between lowland winter areas and high elevation summer ranges.
Range elevation: 1,000 to 5,000 m.
Average elevation: 2,300 m.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: mountains
It has been reported that in places of high mountain goat populations, they cause destruction to plant populations native to that region. This has become a big concern at Olympic and Yellowstone National Parks. Mountain goats are not native to those areas, and are considered an exotic species there. Like other exotic species there is concern about mountain goats bringing in new diseases that will infect native organisms from these areas.
Negative Impacts: injures humans (causes disease in humans )
Because the number of mountain goats has been relatively stable, they are not in any danger of extinction. Some areas, like Yellowstone National Park, have allowed hunters to hunt under controlled conditions to reduce the number of mountain goats. Hunting is not allowed in any places where mountain goats are declining in number, like Cascade Mountains of Washington. Goats in this region are being tagged with GPS collars to track their progress, and find out why their numbers are slowly declining.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: no special status
Mountain goats typically live until their teeth have been worn completely down--on average, 12 to 15 years in the wild and 16 to 20 years in captivity. This age can be determined by the number of annual growth rings on the interior of the horns. Most goats, however, do not survive more than 12 years. The oldest reported male and female were 15.5 and 18 years old, respectively.
Range lifespan
Status: wild: 18 (high) years.
Typical lifespan
Status: wild: 12 to 15 years.
Typical lifespan
Status: captivity: 16 to 20 years.
Mountain goats are stout-bodied with a thick coat made up of white hairs with some brown intermixed dorsally. The pure black horns are about 200 to 300 mm long, rather thin, and present on both sexes. They do not shed these horns--annual growth rings increase the horn size. In this way, the age of the goat can be determined by counting the number of annual growth rings. The male's horn, however, curves back greater than the females. Mountain goats have relatively large, oval hooves with an almost rubber-like sole that aids them in climbing steep rock. They have black scent glands between their horns. The body size of a male and female are similar until 3 years of age. After 3 years of age males are usually 7.5 to 15 cm taller than females. Male mountain goats usually weigh between 61.4 to 81.8 kg and females 56.8 to 70.5 kg.
Range mass: 56.8 to 81.8 kg.
Range length: 1245 to 1787 mm.
Average basal metabolic rate: no information found cm3.O2/g/hr.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger; sexes shaped differently; ornamentation
Average basal metabolic rate: 46.414 W.
The mountain goat's main predators are cougars (Puma concolor). The cougar is versatile enough to move around on the mountains and it is big enough to hunt and kill an adult mountain goat. Bears (Ursus species) may rarely catch a goat when they are on the ground, but if the goats stay on the mountain, it would be extremely difficult for the bear to catch it. Eagles occasionally swoop down and carry off newborns. Wolves (Canis lupus) have been known to also attack mountain goats. In July and August of 1995, one wolf killed a yearling female. However, soon after that incident a adult female successfully defended her kid from an adult wolf. This aggressive defense is rare--a study in 2006 noted just 5 occasions in which mothers defended their kids.
Known Predators:
Prior to and during the breeding season, males compete for females. The do not fight head-to-head but rather stand side-by-side and stab at each other's flanks. Thick skin in this area protects them from serious damage, but deaths have been reported and are usually associated with wounds to the chest, neck, or abdomen.
Courtship begins in September when males attempt to join small bands of females (alone or in pairs). Males tend to be easier to distinguish at this point, as their coats are dirtier--caused by the action of digging a rutting pit. Male courtship behavior involves a low approach to the female, showing the broad side of the face and beard, licking the female's coat, and kicking the female's flanks. In late October, the females finally accept the courtship of males; these males become part of a "nursery band." These include a female, her young, and any males who have joined in the pre-rut season. Males will typically attempt to prevent other males from copulating with any female (including non-estrous females) when in the nursery band.
Mating System: polygynous
Mountain goat breeding season begins in late November and lasts until early January. Gestation is about 150 to 180 days and 1 to 3 kids are born in May to June. The female gives birth on very steep cliffs in her home range to avoid predators. The young are mobile shortly after birth. The young are weaned after 3 to 4 months and stay with the mother until she gives birth the following year. Sexual maturity is reached after 30 months in both sexes, although Cote and Festa-Bianchet (2001) found that kid production was highest among female goats at 8 to 9 years of age. These authors also found that age and social rank were positively correlated, so older females of a higher social rank tend to produce more offspring than lower-ranked, younger females.
Breeding interval: Oreamnos americanus breed once a year in late fall and early winter.
Breeding season: Breeding is from late October through November.
Range number of offspring: 1 to 3.
Average number of offspring: 1.
Range gestation period: 147 (low) days.
Average gestation period: 185.8 days.
Range weaning age: 90 to 120 days.
Average time to independence: 9 months.
Average age at sexual or reproductive maturity (female): 2.5 years.
Average age at sexual or reproductive maturity (male): 2.5 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
Average birth mass: 3200 g.
Average number of offspring: 1.2.
Average age at sexual or reproductive maturity (male)
Sex: male: 912 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 912 days.
Kids stay with their mother until weaned, from 90 to 120 days old. Following weaning, kids typically stay with the mother until another is born, at which point the mother chases away the yearling. Males aid in the protection of young when they are a part of a nursery band; otherwise the mother is the main source of protection.
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Protecting: Female); post-independence association with parents
Mountain goats occur in alpine and subalpine areas with rocky, steep terrain in the Coast, Cascade, and Rocky Mountain ranges [24,110]. Mountain goats occur in forests, krummholz, and alpine meadows varying from temperate rainforests near sea level in coastal British Columbia and Alaska to xeric alpine communities at >13,000 feet (4,000 m) in Colorado [34]. In the northern Rocky Mountains, mountain goats range from approximately 4,900 to 8,900 feet (1,500-2,700 m) [24]. In southern and western parts of their range, mountain goats use primarily areas with steep cliffs, but in their northern distribution they are often found in rolling terrain above treeline [34]. For more information, see Preferred Habitat.
Alaska: On the Cleveland Peninsula in southeastern Alaska, mountain goats occurred in steep, broken terrain at elevations ranging from sea level to >4,900 feet (1,500 m). Below 2,300 feet (700 m), they occurred primarily in old-growth forests of western hemlock (Tsuga heterophylla), Sitka spruce (Picea sitchensis), and western redcedar (Thuja plicata); Alaska-cedar/sedge (Cupressus nootkatensis/Carex spp.) muskegs in poorly drained areas; and alder (Alnus spp.) on steep slide zones. Above 2,300 feet, mountain goats occurred in alpine heath (Ericaceae) interspersed with rock, scree, and snowfields [41,120].
British Columbia: In British Columbia, mountain goats occur from sea level in the western hemlock forest zone in the Coast Ranges to >7,500 feet (2,300 m) in alpine communities in the southern Rocky Mountains. In the Coast Ranges, mountain goats occur in the western hemlock forest zone on cliffs, talus, and sparsely vegetated rocks, often in old growth [103] and in the subalpine mountain hemlock (Tsuga mertensiana) forest zone on rock outcrops and talus, in avalanche tracks, and at seepage sites [104]. Mountain goats occur on cliffs and talus in the interior Douglas-fir (Pseudotsuga menziesii) forest zone [65] and in the interior western redcedar-western hemlock forest zone [82]. They occur in avalanche tracks and on cliffs and talus in the montane interior spruce (Picea glauca × P. engelmannii) forest zone [66]. In the subboreal lodgepole pine-white spruce (Pinus contorta-Abies concolor) forest zone, mountain goats occur in subalpine parklands and grasslands on steep, rugged slopes, in avalanche tracks, and on sparsely vegetated cliffs, talus, and other rock habitats [125]. They occur in grasslands and scrub on rugged slopes in the subalpine Engelmann spruce-subalpine fir (Picea engelmannii-Abies lasiocarpa) forest zone [25]. In the boreal white and black spruce (P. mariana) zone, they occur in grass-shrub communities along major valleys and foothills [31]. Mountain goats occur in rugged terrain in the white spruce-willow-bog birch (Salix spp.-Betula glandulosa) forest zone [106]. At the highest elevations in the alpine zone, mountain goats occur in alpine heath, grasslands, and shrublands on windswept and south-facing aspects, in krummholz, and on cliffs, talus, and sparsely vegetated rock habitats [105]. In southeastern British Columbia, mountain goats used mineral licks in lodgepole pine, Douglas-fir, and spruce-subalpine fir stands that were 96 to 213 years old [107].
Alberta: In Banff and Jasper National Parks, Alberta, mountain goats occurred in rugged, rocky terrain in alpine areas above 7,000 feet (2,100 m) in summer and winter but also occurred in subalpine areas. In subalpine zones, mountain goats used grassy avalanche and rock-slide slopes; rocky slopes and ledges with sparse grass (Poaceae) and sedge cover; and grass-sedge communities on south-facing slopes of burned areas [38]. On Caw Ridge in west-central Alberta, mountain goats occurred in open alpine communities, krummholz, and subalpine fir-Engelmann spruce forest from 5,740 to 7,120 feet (1,750-2,170 m), where treeline occurred at approximately 6,200 feet (1,900 m). They occurred on gently rolling hills, rockslides, steep grassy slopes, and short cliffs [35]. In west-central Alberta, mountain goats occurred on talus and cliffs in a canyon along Pinto Creek. They occurred in lodgepole pine and white spruce forests with an understory of Labrador tea (Ledum groenlandicum) and Schreber's moss (Pleurozium schreberi) and traveled through riparian habitats dominated by willows, young quaking aspen (Populus tremuloides), and scattered white spruce trees [57].
Washington: In Washington, mountain goats occurred in mountain hemlock, Pacific silver fir (Abies amabilis), subalpine fir, and alpine larch (Larix lyallii) forests and in heath habitats dominated by mockorange (Philadelphus spp.), mountain heather (Cassiope spp.), and partridgefoot (Luetkea pectinata) [84]. In Olympic National Park below 4,900 feet (1,500 m), introduced mountain goats occurred in Douglas-fir-western hemlock forests with rock outcrops and bluffs. Above 4,900 feet, they occurred in subalpine fir forests, subalpine meadows, and herb-dominated communities on talus, scree slopes, and rock [71]. In the north-central Cascade Range, mountain goats occurred from 700 to 5,000 feet (200-1,500 m). At low elevations, mountain goats occurred in western hemlock and Douglas-fir forests. At mid- to upper elevations, they occurred where cliffs and steep, rocky terrain occurred in mountain hemlock and fir (Abies spp.) forests [45].
Idaho: In the Pahsimeroi River drainage in winter, mountain goats occurred in curlleaf mountain-mahogany (Cercocarpus ledifolius) habitat on steep, south-facing cliffs [85]. On winter range at 4,000 to 5,000 feet (1,200-1,500 m) elevation in the Selkirk Range of northern Idaho, 20-year-old postfire shrub communities dominated by Rocky Mountain maple (Acer glabrum), rose (Rosa spp.), serviceberry (Amelanchier spp.), black chokecherry (Prunus virginiana var. melanocarpa), Lewis' mockorange (Philadelphus lewisii), and redstem ceanothus (Ceanothus sanguineus) were considered the most important foraging sites for mountain goats [17].
Montana: In northwestern Montana in the Swan Range, mountain goats occurred in meadows at 6,800 feet (2,100 m) and on talus slopes near mountain summits at 7,600 feet (2,300 m) [32]. They used cliffs, ledges, and rock outcrops dominated by moss, spikemoss (Selaginella spp.), and grasses, primarily bluebunch wheatgrass (Pseudoroegneria spicata) and bluegrass (Poa spp.); sparsely vegetated dry meadows dominated by bluebunch wheatgrass and sedges; windswept, sparsely vegetated ridgetops dominated by grasses such as bluebunch wheatgrass and purple pinegrass (Calamagrostis purpurascens) and forbs such as sticky cinquefoil (Potentilla glandulosa); shrub- and herb-dominated ravines where avalanches occurred regularly; wet meadows, often near cliff bases; and subalpine fir/menziesia (Menziesia ferruginea), subalpine fir-Engelmann spruce-grand fir (Abies grandis), and whitebark pine (Pinus albicaulis) forests [20]. In south-central Montana, introduced mountain goats in the Absaroka Mountains occurred in tufted hairgrass (Deschampsia cespitosa)-sedge meadows above treeline (>9,500 feet (2,900 m)) and in whitebark pine and subalpine fir stands at treeline [128]. In summer on Running Rabbit Mountain in Glacier National Park, mountain goats preferred subalpine fir/beargrass (Xerophyllum tenax) krummholz, mesic alpine forb meadows, a mineral lick, and rock outcrops (bedrock, talus-scree, forb outcrop, shrub outcrop, and forested outcrop) more than expected based upon availability (P<0.05 for all variables) [118].
South Dakota: In the Black Elk Wilderness, introduced mountain goats occurred in ponderosa pine (Pinus ponderosa) forest interspersed with granite outcrops, open ridges, and meadows [12].
Colorado: An introduced mountain goat population in the Sawatch Range occurred at 9,120 to 13,230 feet (2,780-4030 m). Above treeline at 11,480 feet (3,500 m), mountain goats occurred in open alpine habitats with herbs and patches of Engelmann spruce, bristlecone pine (Pinus aristata), and willows. Below treeline, mountain goats occurred in Engelmann spruce, Douglas-fir, bristlecone pine, and lodgepole pine forests interspersed with cliffs and old burns dominated by quaking aspen or shrubs [3,10]. In the Gore Range, an introduced mountain goat population occurred on an alpine ridge dominated by tufted hairgrass, sheep fescue (Festuca ovina), sedge, and clover (Trifolium spp.), with some willow stands [67].Mountain goats are polygamous [78,99,100]. The rut—the peak breeding period—occurs from late October to December, but primarily in November [24,110]. Based on the short birthing period in spring, it is likely that most females in a population attain estrus within a 2-week period [24].
Sexually active males fight and use aggressive displays to gain dominance and access to females for mating [78]. Large males are usually dominant and mate most often [24]. Dominant males defend one estrous female at a time ("tending tactic") [100] for up to 2 to 3 days [135]. Subordinate males attempt to mate by pursuing females ("coursing tactic") [100]. Males attempt to breed as many nannies as possible [78] by moving among nanny groups during the rut [135]. A 2003 review stated that it was not known whether females mate with more than one male [24]. See Age at first reproduction for more information.
As of this writing (2010), no observations of direct fire mortality of mountain goats were recorded in available literature. Kelsall and others [80] concluded that because mountain goats live primarily on treeless alpine rangelands, direct fire mortality is "unlikely". However, Toweill [133] observed few mountain goats along a portion of the lower South Fork Salmon River in Idaho that burned in a wildfire about 10 years prior to the study. Because the burn appeared to be good habitat for mountain goats, the author speculated that direct mortality during the fire was substantial, and without a colonizing source of mountain goats, the habitat remained "near vacant". However, no prefire census of the mountain goat population was conducted [133].
General observations suggest that mountain goats occasionally use areas during and soon after fire. A yearling male mountain goat in the Swan Range, Montana, was observed at a lick while slash-burning and road-building occurred nearby [20].
Diseases and parasites: Ticks (e.g., Rocky Mountain wood tick (Dermacentor andersoni), winter tick (D. albipictus) and spinose ear tick (Otobius megnini)), biting lice (Damalinia parallelus), lungworms (Protostrongylus stilesi and P. rushi), nematodes (e.g., Nematodirus maculosus and N. fillicollis), and tapeworms (e.g., Thysanosoma actinoides and Cysticercus tenuicollis) infest mountain goats [62,99,110]. A 1983 review reported high mortality of kids in a mountain goat population heavily infested with nematodes in the northwestern Cascade Range [78]. Protozoan parasites in the genus Sarcoscystis occur in mountain goat muscle tissue. According to a review, in Washington 43% of mountain goats were infested, and in Alberta 73% were infested. As of 2000, it was unclear whether sarcocyst infections kill mountain goats [99]. White muscle disease resulting from selenium deficiency may kill mountain goats (Hebert and Cowan 1971 cited in [99]). Although mountain goats are infested with many parasites, Kerr and Holmes (1966 cited in [24]) found no evidence that parasitism has a strong effect on individual body condition, survival, or reproduction. As of this writing (2010), however, no studies had examined the ecological effects of parasites on mountain goats. Brandborg [17] did not consider parasites and diseases an important source of mortality in mountain goats, but he suggested that they may contribute to mortality during severe winters when animals suffer from malnutrition. See Johnson [78] and Toweill and others [135] for reviews of diseases and parasites affecting mountain goats.
Sources of mortality: Sources of mountain goat mortality include predators, hunting, and accidents. Snow depth and morphology may increase mountain goat susceptibility to predation, malnutrition, accidents, diseases, and parasites [138]. See Weather for more information on this topic.
Predators: A 2003 review concluded that predation is likely the most important cause of mortality in mountain goats [24]. Mountain goat predators include mountain lions (Puma concolor), bobcats (Lynx rufus), gray wolves (Canis lupus), coyotes (Canis latrans), wolverines (Gulo gulo), American black bears (Ursus americanus), brown bears (Ursus arctos), and golden eagles (Aquila chrysaetos) [21,24,35,62,78,99,110]. The most important predators are mountain lions, gray wolves, and brown bears [24,42,78,110]. Coyotes and wolverines primarily consume mountain goat carrion [68,78,110], but anecdotal evidence suggests that they may attempt to kill mountain goats [20,24,48,111]. Golden eagles may be particularly important predators of <2-week-old kids [62,78].
Predation can be high in some populations. In west-central Alberta, 88% of annual juvenile mortality was due to predation by gray wolves, grizzly bears (Ursus arctos horribilis), and mountain lions [135]. Festa-Bianchet and others [35] suggested that because mountain goat densities on Caw Ridge were low, predation was likely incidental or opportunistic, and thus, unlikely to regulate the mountain goat population. Festa-Bianchet and Cote [34] stated that very few mountain goat populations are large enough to sustain or be a major food source for a population of predators, although an individual predator such as a mountain lion may specialize on mountain goats and affect a population's dynamics. In southeastern Alaska, gray wolves killed mountain goats, and mountain goat occurred in 53% of gray wolf scats. The authors attributed a decline in the mountain goat population during 5 years in part to gray wolf predation [42].
Hunting: Mountain goat population declines have been related primarily to overharvest [99]. For more information on this topic, see Population management.
Accidents and other sources of mortality: Although a 2003 review concluded that accidents are not a frequent mortality factor in mountain goats [24], a study in southeastern Alaska reported that snowslides were the most common cause of nonhunting mortality [83], and a study in the Salmon River drainage, Idaho, found that snowslides were responsible for more accidental deaths than any other natural cause [17]. Climbing accidents, starvation, separation of kids from their mothers, motor vehicle accidents, and aggressive interspecific fighting, particularly during the rut, have also caused injury and mortality in mountain goats [17,21,24,78,110].
Mountain goats use fire-created habitats, and mountain goat populations often increase after fire (see Indirect Fire Effects). This suggests that using prescribed fire to remove dense forest stands and increase grasses and shrubs may benefit mountain goats [99]. Some researchers suggested that prescribed fire may be used to improve mountain goat forage [12,14]. In western Washington, where dense forest stands offer poor habitat for mountain goats, Johnson [78] suggested that prescribed fire could be used to reduce dense conifers in patches and increase early-successional species used as forage near rocky terrain. In eastern Washington, where conifer stands are sparse, habitat is dominated by grasses and shrubs, and conditions are dry, he suggested using prescribed fire to increase shrub density via sprouting and to stimulate grass production. Houston and others [69] suggested using prescribed fire to increase the carrying capacity of mountain goat winter rangelands on the Olympic National Forest. Wisdom and others [145] recommended increasing the quantity and quality of mountain goat forage in the interior Columbia Basin, where succession caused forage reductions, by using prescribed fire to restore historical FIRE REGIMES and vegetation patterns.
Based upon expert opinion, prescribed fire should be used in or adjacent to good mountain goat winter range, such as on south-facing slopes along steep ledges, cliffs, or rock outcrops [78]. Foster and Rahs [40] recommended prescribed fires in areas close to steep escape terrain to create early-seral plant communities for mountain goats, but they cautioned that small islands of conifers should be protected within the burn perimeter to provide cover. Taylor and others [130] suggested that fires near winter range on sites with snow-shedding characteristics may be particularly beneficial for mountain goats. Johnson [78] considered elevation an important criterion in selecting sites suitable for use of prescribed fire in mountain goat habitats. He suggested that prescribed fires in Washington be set at elevations no higher than 6,000 feet (2,000 m) because vegetation growth is slow at higher elevations and soils at high elevations are usually fragile and can be sterilized by a "hot" fire [78].
Although often recommended, prescribed fire has been infrequently applied in mountain goat habitats. Techniques for burning under prescription to improve bighorn sheep subalpine rangelands (e.g., [11,147]) may also improve mountain goat rangelands because these species' diets and rangelands often overlap (e.g., [28,137]). For more information, see the FEIS review of bighorn sheep.
Some researchers advocate that wildfires in mountain goat habitats be allowed to burn [14,133]. Toweill [133] stated that allowing wildfires within mountain goat habitats would reduce tree encroachment on subalpine and alpine meadows and would likely promote sprouting in shrubs important in mountain goat diets. Possibly a combination of prescribed fires and wildfires for resource benefit combined with population management techniques, such as hunting restrictions, may be needed to increase mountain goat populations.
Some researchers caution that wildland fire may be detrimental to mountain goat populations in areas where mountain goats use mature forests for forage and cover [16,60]. In northwestern British Columbia, a conifer forest close to a canyon rim was important mountain goat winter range. The authors recommended planting conifers in large areas burned by a wildfire 10 to 20 years prior to the study to increase cover for mountain goats [40]. Prescribed burning and its associated human activities in mountain goat range may be harmful to mountain goat populations in the short term by increasing stress levels and altering movements and behaviors (see Human disturbance) [97].
FIRE REGIMES in mountain goat habitats vary across the species' distribution. Mountain goat habitats in the Rocky Mountains are characterized by large, treeless alpine areas, whereas mountain goat habitats in the Cascade Range include few alpine communities. Most of the alpine zone on the Pacific Coast in British Columbia and Alaska is occupied by glaciers, snowfields, bare rocks, and talus slopes, and fire is uncommon because of lack of fuels [78]. Fire's infrequency in alpine habitats caused several researchers to comment that fire was likely to have little effect on mountain goat populations [33,37,62,148]. However, mountain goats occur in habitats with short (e.g., subalpine woodland and montane and subalpine grasslands) to long (e.g., Sitka spruce-western hemlock and mountain hemlock) fire-return intervals and in those with understory fir regimes (e.g., Rocky Mountain Douglas-fir (Pseudotsuga menziesii var. glauca)), mixed FIRE REGIMES (e.g., whitebark pine-lodgepole pine and grand fir (Abies grandis)-lodgepole pine-western larch (Larix occidentalis)-Douglas fir), and stand-replacement FIRE REGIMES (e.g., lower and upper subalpine fir-Engelmann spruce and mountain grassland).
In Washington, mountain goats occur in mountain hemlock, Pacific silver fir, subalpine fir, and alpine larch forests and in heath habitats. Mountain hemlock forests are typically moist; historically, fires were generally infrequent and stand-replacing, occurring at 400- to 800-year intervals. Fire in Pacific silver fir stands was infrequent due to the relatively short summers, high humidity, and high precipitation associated with these forests. Fire-return intervals were reported to be as long as 500 years. When fires occur in Pacific silver fir stands, they are typically stand-replacing owing to the buildup of abundant fuels. Subalpine fir forests at high elevation generally experience high-severity, stand-replacing fires at intervals of 100 years or more. Subalpine fir forests at low elevation often have more frequent, less severe fires than those at high elevation. Subalpine fir habitats in subalpine zones burn infrequently because of discontinuous fuels, broken, rocky terrain, and moist, cold environments in adjacent uplands. Stand-replacing fire is rare in alpine larch habitats because of abundant cliff, talus, and rock sites with little or no fuels. Fires are usually restricted to the immediate vicinity of the lightning-struck tree. In heath habitats, fires are infrequent because heath is interspersed with rock and wetlands, and because the sites have short growing seasons, low-statured plants, moist soils, and relatively cold temperatures. However, heath stands may burn during periods of severe drought [84]. For more information on FIRE REGIMES in mountain goat habitats in Washington, see Kovalchik and Clausnitzer [84].
In Montana, mountain goats occur in cold, moist upper subalpine and timberline habitats. These habitats are "cold, moist, rocky, snowbound, unproductive, and otherwise fire resistant". Upper subalpine and timberline habitats generally experience stand-replacing fires at intervals of 200 years or more. Stand-replacing fires are most likely to occur in these habitats during drought, when crown fires develop in the forests below and burn uphill. Vegetation growth following fires is usually slow because of the extremely short growing season and cold climate. Mountain goats also occur in lower subalpine habitats. Historically, periodic (30- to 130-year intervals) low- to moderate-severity fire and infrequent stand-replacement fire occurred, depending upon plant species composition, soil moisture, topography, weather, and past fire. In Douglas-fir habitats, frequent (5-45 years) low- or moderate-severity fires maintained open forest stands and grasslands favorable to mountain goats. Mountain goats occur in lodgepole pine forests above 7,500 feet (2,300 m) that historically had stand-replacing fires at 300- to 400-year intervals. In low-elevation lodgepole pine forests, stand-replacing fire occurred at <100-year to 300-year intervals [37]. For more information regarding FIRE REGIMES in mountain goat habitats in the northern Rocky Mountains, see Arno [7]. The Fire Regime Table summarizes characteristics of FIRE REGIMES for vegetation communities in which mountain goats may occur. Follow the links in the table to documents that provide more detailed information on these FIRE REGIMES. Find further fire regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find FIRE REGIMES".
Fire exclusion during the 1900s resulted in increased density of trees in formerly open stands, reducing mountain goat forage quantity and quality. This has caused mountain goat rangeland deterioration and loss of quality habitat throughout the species' range [14,78,145]. Some grasslands used by mountain goats are the result of past fires, and fire exclusion has resulted in the lack of new grassland development in some areas [139]. Without periodic fire, seral grasslands often become dominated by conifers [113]. Fire exclusion has increased fuel loads in many mountain goat habitats, potentially leading to increased frequency and/or severity of fires [78], which could benefit mountain goat populations.
Diet: Along the continuum from grazers to browsers, mountain goats are classified as intermediate or mixed feeders and can switch from a diet composed primarily of grasses to one of browse [24,28]. In a review, Johnson [78] commented that the "most predictable feature of mountain goat diets is their variability". Mountain goats are generalists and usually consume foods according to availability [24,96,99]. Mountain goats eat the flowers, stalks, seeds, and pods of grasses and forbs. They eat the stems, leaves, and bark of trees and shrubs. They also eat lichens, mosses, and ferns and dig up belowground plant structures such as fern rhizomes, roots of perennial forbs, bulbs, and tubers [20,24,63,74]. Mountain goats select young, highly nutritious plant parts when available, preferring flowers, seed heads, and growing leaves or leaf blades. The proportion of browse in mountain goat diets often increases during severe winter weather or when other forage is unavailable [74].
According to a 1983 review, in summer, mountain goats consume 12% to 82% grasses, 14% to 64% forbs, 0 to 1% conifers, 0 to 70% shrubs, and 0 to 3% lichens, mosses, and ferns. In winter, they consume 1% to 90% grasses, 0 to 18% forbs, 0 to 73% conifers, 1% to 47% shrubs, and 0 to 28% lichens, mosses, and ferns [43]. A 1994 review summarized 10 studies on feeding habits of mountain goats and found that summer diets averaged 52% grasses, 30% forbs, and 16% browse. Preferred plants in summer were bluegrass (Poa spp.; 14%), sedge (10%), wheatgrass (Triticeae; 9%) bluebell (Mertensia spp.; 6%), fescue (Festuca spp.; 5%), hairgrass (Koeleria spp.; 5%), and willow (Salix spp.; 4%). In winter, the average diet contained less biomass from forbs (8%) and more from browse (32%). The preferred plants were fescue (18%), sedge (8%), wheatgrass (4%), bluegrass (4%), sagebrush (Artemisia spp.; 3%), hairgrass (1%), and willow (1%) (Laundre 1994 cited in [24]).
In winter, forage availability, and thus mountain goat diet, changes with snow depth and hardness. When snow is shallow, mountain goats paw through it to reach understory vegetation but also browse shrubs, conifers, and lichens that protrude from the snow [20,21,56]. Deep snow can limit mountain goat use of forage to that which protrudes from the snow or cause mountain goats to move to areas with shallow snow [3,21]. On ranges where windblown slopes and ridgetops are available in winter, grasses and sedges constitute a high proportion of the diet. On coastal ranges, conifers and shrubs that protrude above the snow provide most of the winter diet [99]. When forage is limited in winter, mountain goats may eat more twigs and needles of conifers, such as lodgepole pine [40], Engelmann spruce [3], subalpine fir [20,111,115], whitebark pine [111], ponderosa pine [19], common juniper (Juniperus communis), Rocky Mountain juniper (J. scopulorum) [19,20,111], western yew [20], Douglas-fir [3,19,20], western hemlock, mountain hemlock, and Alaska-cedar [41]. Stomach contents of an introduced population in the Crazy Mountains, Montana, averaged 25% conifers in winter and 13% conifers in spring, but in summer and fall conifers constituted only trace amounts of the diet [115]. In old-growth western hemlock, Alaska-cedar, and Sitka spruce forests on the Cleveland Peninsula in southeastern Alaska, mountain goat use of trees, particularly conifers, increased with increasing snow depth, while use of grasses, forbs, ferns, and shrubs decreased [41]. Brandborg [17] reported heavy use of whitebark pine and subalpine fir as "emergency forage" in years when deep snow made other forage unavailable. In Montana, mountain goats that died from malnutrition usually had large amounts of conifer needles in their stomachs [19]. In contrast, in alpine habitat in the Sawatch Range, Colorado, conifers constituted more of the mountain goat's diet during a mild winter than during a severe winter. During the severe winter, deep snow restricted mountain goats to windswept ridges resulting in increased consumption of grasses and sedges and reduced consumption of woody plants and forbs. Woody plants and forbs tended to occur in krummholz and swales that collected snow [3]. Similarly, mountain goats wintering in the Swan Range, Montana, mostly consumed grasses and sedges on windblown slopes because most shrubs were covered by deep snow and were therefore unavailable [20].
Deep snow may be particularly deleterious to young mountain goats. Young mountain goats have difficulty pawing through deep and/or crusted snow and often feed and bed in craters pawed and utilized by older animals, particularly their mothers. Kids and yearlings were frequently observed feeding after older mountain goats had bedded following a feeding session [21]. On Klahhane Ridge, yearling mountain goats spent more time feeding and less time bedding than any other age class. Kids spent less time feeding and more time bedding than other age classes [126].
Mountain goat kid near Logan Pass, Glacier National Park, Montana. Photo courtesy of Rachelle Meyer, US Forest Service.Use of lichens and mosses by mountain goats often increases in winter, particularly during deep snows. In old-growth forests on the Cleveland Peninsula in southeastern Alaska, lichens (e.g., witch's hair lichen (Alectoria spp.), bear lichen (Usnea spp.), and lung lichen (Lobaria spp.)) and mosses (e.g., feather moss (Hylocomium spp.), goose neck moss (Rhytidiadelphus spp.), and toothed sphagnum (Sphagnum cuspidatum)) constituted 35% of the diet when snow was <20 inches (50 cm) deep in open areas, 49% when snow was 20 to 59 inches (50-150 cm) deep, and 57% when snow was >59 inches deep [41]. Mosses and lichens constituted 60% of the winter diet in the Black Hills, South Dakota [56]. Conversely, in the Crazy Mountains, Montana, mosses, lichens, and ferns constituted 3% of the diet of an introduced mountain goat population by volume in summer, but in winter they constituted only trace amounts [115]. In the north-central Cascade Range, where mountain goats mostly used open habitats such as clearcuts and open forests in winter, mountain goats only consumed an average of 3% lichens and mosses and 6% ferns during the 2-year study; instead, they consumed mostly conifers (45%) and shrubs (22%). Lichens and mosses may be more important in mountain goat winter diets in coastal populations than in interior populations [45].
Mountain goat forage quality is highest during late spring and early summer, when rapid plant growth occurs. Forage quality declines over summer and fall as vegetation matures, and it is lowest during winter, when plants are dormant. Forage quantity is greatest in midsummer and most limited during winter, when mountain goat distribution is constrained by deep snow and mountain goats feed on a less diverse, fixed quantity of dormant plants [74]. Winter forage abundance is often considered most limiting to mountain goat populations (e.g., [17,71]), but spring weather or timing of access to new plant growth in spring may be more important than winter conditions (see Weather) (Festa-Bianchet personal communication cited in [94]).
Water: Mountain goats drink water and eat snow [40,110,126]. Water is not a limiting factor on most mountain goat ranges because springs, snow, and abundant run-off from melting snowbanks are usually available year-round [16,17,19,83,90]. However, water availability may restrict mountain goat movements and habitat selection in warm, dry southern parts of the species' distribution [16,78]. In the Pasayten Wilderness, northern Cascade Range, Anderson [6] observed daily movements to water. Lack of water in July caused mountain goats to move to areas with water [6].
Mountain goats, particularly females, show strong fidelity to established seasonal ranges [21,99]. Within home ranges, use patterns are "highly predictable", with individuals using the same travel routes, feeding sites, and bedding sites daily. Males are more likely than females to show variable movement patterns and to travel through atypical terrain [21].
Daily activity: Mountain goats feed throughout the day but are most active from dawn to midmorning and again from late afternoon to evening. They are often inactive at midday [17,19,24,110,118,119,126]. Because bedding and foraging sites may be remote from each other, mountain goat movements often peak during travel to and from these areas. Thus, mountain goat movements typically peak at dusk, midday, and dawn [126]. Mountain goats are frequently active at night [17,20,24,110,111,126]. Weather, particularly temperature, affects mountain goat daily activity. During hot midsummer days, afternoon activity is often reduced [20,24]. Conversely, cloud cover may increase midday feeding activity in summer [17,126]. During inclement weather mountain goats remain relatively inactive [17,19,20,62,78].Seasonal movements and migration: Some mountain goat populations have distinct summer and winter ranges, whereas others remain in the same area throughout the year [24]. Winter ranges are frequently at lower elevations than summer ranges (e.g., [17,43,119]). If mountain goats are at high elevations in winter, they preferred windswept slopes with minimal snow accumulation (e.g., [43,47,111]). On the coast of Alaska, mountain goats summered at high elevation (5,600 feet (1,700 m)) in alpine habitats and wintered from alpine habitats down to sea level in rock outcrops surrounded by forest [43]. In the Olympic Mountains, introduced mountain goats summered above 5,000 feet (1,500 m), although they occurred as low as 2,000 feet (600 m). They wintered on steep south- and southeast-facing outcrops and cliffs below 5,000 feet but were found as low as 1,000 feet (300 m) [117]. On mountain ranges along the breaks of the Salmon River in Idaho, mountain goats moved to low elevations in winter, moving to their lowest elevations in April and early May to access new growth on south-facing slopes [17]. In coastal and interior British Columbia, mountain goats usually remained at low elevations in spring in order to obtain the earliest flush of green vegetation. As spring progressed into summer, they followed the development of new growth upwards. In summer and early fall, most mountain goats grazed at and above treeline, where they used lush alpine swales and boulder meadows adjacent to steep cliffs. In coastal British Columbia, winter ranges were at low elevations because at high elevations the deep, heavy snow was not readily blown away to expose forage, while sites near sea level had little or no snow. Mountain goats occasionally wintered on cliffs that rose directly from the beach. In interior British Columbia, where snow was usually shallower and drier and high winds were frequent, mountain goats wintered on cliffs at varying elevations, including high windswept ridges. Most winter ranges throughout coastal and interior British Columbia were steep sites that shed snow and had south to west exposures [14].
Migration distances range from <1 mile to >10 miles (2-16 km) [78]. In the Sapphire Mountains, Montana, migration distances between summer and winter activity centers ranged from 1.1 to 6.9 miles (1.7-11.1 km); mountain goats migrated greater distances on average during a severe winter (5.7 miles (9.2 km)) than during a mild winter (1.8 miles (2.9 km)). During the severe winter, mountain goats traveled to lower elevations than during the mild winter, whereas during the mild winter, mountain goats rarely left their summer-fall ranges [111]. In the Kenai Mountains, southeastern Alaska, some mountain goats used small home ranges year-round, whereas others migrated >15 miles (24 km) between winter and summer ranges [98]. In the Bitterrroot Mountains, Montana, mountain goats migrated 5 to 10 miles (8-16 km) between ranges [119].
Mountain goats, particularly females, show strong fidelity to established seasonal ranges [20,21,74,78,99,130]. In Olympic National Park, 84% of mountain goats returned to the same summer ranges each year, some for 5 to 10 years [74]. In southeastern Alaska, mountain goats moved from high-elevation summer range to winter range below treeline, usually on the same mountain, although erratic movements to new ranges sometimes occurred [96]. In the Kenai Mountains, adult males ≥5 years old showed the highest fidelity to their summer ranges, and adult females ≥5 years old showed the second highest fidelity. During winter, adult females showed the highest fidelity to winter ranges, and adult males showed the most mobility and least fidelity. Young females showed fidelity similar to that of older females, whereas young males were the least faithful to a given range and most prone to change ranges [98]. In general, males are more likely than females to show variable movement patterns and to travel through atypical terrain. In northwestern Montana, all breeding took place on nursery-band wintering areas; so, in the fall, females returned to the same wintering ranges, while rutting males crossed between ranges to access estrous females [21]. Before returning to separate or peripheral ranges around midwinter (depending upon snow depth), adult males then spent at least early winter on whichever nursery band's range they occupied at the end of the rut [21,85]. Several researchers reported that males made extensive movements during the rut in populations where the distance between neighboring groups of females was large [24,78].
Mountain goat habitats are characterized by low mean temperatures, high winds, prolonged snow cover, short growing seasons, and intense ultraviolet radiation [94]. Because summer is short, mountain goats may spend more time on winter range than summer range. In the Cascade Range, the median time mountain goats spent on summer range was 4.6 months, with the remaining time spent on winter range [109]. Because snow melts slowly above 4,000 feet (1,200 m), use of alpine areas in southeastern Alaska was "brief" [96].
Dispersal: Dispersal is commonly reported in mountain goat studies (e.g., [30,78,142]). A review of studies of mountain goats on Caw Ridge concluded that young mountain goats of both genders have "strong dispersal tendency" [34]. Typically, males are more likely to disperse than females, and juveniles (1-3 years old) are more likely to disperse than adults [34,35,53,73,127]. On Klahhane Ridge, 10% of mountain goats in a high-density population dispersed over 4 years. Males (20%) dispersed more frequently than females (6%), and 1- to 3-year-olds (18%) dispersed more frequently than older mountain goats (5%) [73]. Dispersal distances up to 19 miles (30 km) were reported in native populations [35]. Exploratory movements up to 38 miles (61 km) were reported for introduced mountain goats [134]. High population density and resource limitation may prompt dispersal [73,78,127].
Home range: According to a 2000 review, annual mountain goat home range sizes range from 2.4 to 17.3 miles² (6.3-44.9 km²) [99]. Males often have smaller home ranges than females (e.g., [24,34,118]), although in southeastern British Columbia [108], southeastern Alaska [120,141], and Montana [79] males had larger home ranges than females. Researchers hypothesized that females with kids may travel more than males because longer movements could make their location less predictable to predators [24,34]. Conversely, males may travel more than females because males often move long distances between groups of females during the rut [17,20,40,44].
Summer ranges are often larger than winter ranges [47,78,119]. During winter, when deep snow hinders movements, mountain goats may be confined to small areas for long periods [17,20,24,44,62,63]. Near the Salmon River, Idaho, a band of 10 mountain goats lived for 3 months on a winter range <200 acres (81 ha) [17]. In the Swan Range, Montana, wintering mountain goats used 8.6 acres (3.5 ha) [20]. In the East Kootenay region of southeastern British Columbia, winter home range was <15% of their annual home range, indicating restricted movement during winter. During a winter when snow depth was 25% to 40% below average, winter ranges were 3.4 times larger for males and 2.2 times larger for females than during a winter when snow depth was within 10% to 15% of average [108]. In Colorado, home range sizes of an introduced mountain goat population did not differ between 2 summers, but summer home ranges were 8 times greater than winter home ranges. Winter range sizes were apparently not limited by deep snow [4].
Mountain goat home range sizes and movements may be modified by the presence of licks. In Colorado, mountain goat movements in summer seemed limited by licks occurring at one end of the study area. When a new lick was established at the other end of the area, movements expanded (Bailey unpublished data cited in [16]).
Mountain goat populations respond directly to fire-caused changes in cover and food. Fire's occurrence and its impacts on mountain goat populations apparently vary between alpine and forest habitats [78]. In general, the literature regarding fire effects in alpine and subalpine mountain goat ranges suggests that fire increases mountain goat forage availability and diversity, particularly herbs and shrubs important in the diet, and reduces tree encroachment, potentially for long periods. Thus, fire in alpine and subalpine habitats may lead to increases in mountain goat populations [78,99,132]. However, in low and midelevation forests, fire may reduce important mountain goat forage and cover, particularly on winter rangelands [60]. The effects of fire on mountain goat habitats are not thoroughly understood but likely depend upon prefire mountain goat population density, the plant communities affected, the type of fire, postfire vegetation growth rates, and adjacent habitats. Most reports are anecdotal, use small sample sizes, or include no controls and/or replicates, so results presented here should be interpreted with caution.
Mountain goats use burned areas throughout their range. In Banff and Jasper National Parks, Alberta, mountain goats used grass-sedge communities in burned areas on south-facing slopes [38]. In southwestern Idaho near McCall, mountain goats were commonly observed in a 3-year-old burn in lower Big Creek [133]. In the Stikine River drainage in northwestern British Columbia, they used 10- to 20-year-old burns 24% of the time. Burns were particularly important as mountain goat foraging areas in spring and fall [40]. In the Red Butte Range, Montana, mountain goats wintered in an area burned about 30 years prior to the study that was "covered by various associations of shrubs, grasses and weeds, with a scattering of dwarf alpine trees" [18]. Mountain goats also traveled 0.5 mile (0.8 km) through burned habitat with abundant windfalls and snags [17]. Mountain goats in the Sapphire Mountains, Montana, used a salt lick in an area that was burned in a wildfire about 50 years prior to the study and was never reforested [111]. In coastal British Columbia, mountain goats commonly used burned habitats, but the authors speculated that use of burned habitat may decline in winter due to the deep snow in burns [130].
Mountain goat populations may decrease immediately following fire due to loss of winter forage and cover, increase as postfire herb and shrub communities develop and forage becomes more abundant, and then decrease due to forest succession. In southwestern Idaho near Nampa, a summer wildfire burned through forested habitat and into adjacent grasslands with scattered shrubs and trees that occurred throughout cliff areas used by mountain goats. The mountain goat population apparently declined the spring following the fire [133], probably due to a loss of winter forage. However, other researchers reported use of burns soon after fire (Miller 1984 unpublished report cited in [49]).
Several researchers reported increased mountain goat populations from about 4 to 18 years following fire. Mountain goat populations increased following a wildfire on Chopaka Mountain in north-central Washington [78]. Prior to the fire, the mountain goat population was very small, apparently due to marginal rangeland. The mountain goat population "irrupted" after the fire, and in postfire year 12 the mountain goat population peaked at 250 individuals. The population increase was attributed to the creation of early-seral plant communities with abundant forage. The mountain goat population then declined, reaching its lowest point 41 years after the fire (King personal communication cited in [78]). On Baldy Ridge in the Olympic Mountains, Lack (1962 unpublished field notes cited in [73]) reported that mountain goats heavily grazed grasses throughout several burned areas; one burn was 12 years old, another was 23 to 46 years old, and the 3rd was at least 63 years old. Houston [73] noted that mountain goat populations on Baldy Ridge declined over 37 years as forest cover increased. After the Penticton Creek fire in south-central British Columbia, an unhunted mountain goat herd expanded its range into the burned area. The herd increased from <20 individuals prior to the fire to a peak of 45 individuals in postfire year 18. Thirty-two years after the fire, the herd had declined to 28 individuals, and 35 years after the fire, the herd had 20 individuals. The authors stated that the herd apparently declined because habitat that was opened up by the fire had succeeded to closed-canopy lodgepole pine forests that were not suitable for mountain goats [49]. In central Idaho, wildfire on alpine and subalpine areas increased forage for mountain goats and apparently resulted in increased mountain goat populations by postfire year 4, but observations were confounded by increased visibility of mountain goats and thus detection by observers [132,133]. Mountain goat's ability to increase following fire led Johnson [78] to suggest that they "obviously evolved with periodic fires and seem to have benefited from their occurrence" historically.
Mountain goat populations may increase following fire because fire sets back forest succession and increases forage abundance and plant species diversity [78]. Along Lake Chelan in the Cascade Range of central Washington, a 5- to 6-year-old burned area provided "good forage conditions" for mountain goats reintroduced into native range near the area. The authors speculated that abundant forage in the burn may have been the reason the released mountain goats persisted in the burn [36]. On Mt Hamell in Alberta, many of the grasslands used by mountain goats were created by fires, with little postfire conifer regeneration [139]. In coastal British Columbia, burned areas "appeared to attract goats", and mountain goats used second-growth forests created by fire more frequently than expected. The authors noted that mountain goats used logged but unburned habitats very little. Most second-growth forests used by mountain goats were 20 to 40 years old. The authors surmised that mountain goats used the burns because of increased forage quantity and/or quality and because the burns were snow-free during winter [130]. On Mt Wardle in Kootenay National Park, British Columbia, a fire burned a conifer forest up to 7,005 feet (2,135 m). Much of the mountain goat winter range, which extended from about 4,000 to 8,500 feet (1,220-2,590 m), occurred in the burned area (Debock 1970 cited in [80]). Debock (personal communication cited in [80]) speculated that had it not been for the fire, mountain goats might not have occurred on the mountain. On winter range at 4,000 to 5,000 feet (1,200-1,500 m) elevation in the Selkirk Range of northern Idaho, seral shrub communities, which were the most important foraging sites for mountain goats in winter, had been kept in early succession by a fire that occurred approximately 20 years prior to the study and by avalanches [17]. Shortly after a wildfire near Sitkum Creek, British Columbia, mountain goats occurred throughout the burned area. Fifteen years after the fire, they avoided parts of the burn that had succeeded to forest but used burned areas at the base of cliffs where vegetation regrowth was slower (Miller 1984 unpublished report cited in [49]). The mountain goat herd at Sitkum Creek did not increase following the fire, possibly because population density was very low prior to the fire due to overhunting and "there were probably too few goats present to take much advantage of the burn" [49].
Some researchers reported that mountain goats are likely little affected by fire because fire is unlikely to occur in their habitat [33,37,62,148]. A 1987 review of fire effects in western Montana forests stated that mountain goats are likely "relatively impervious" to fire effects because they usually occur above fire-prone forest areas in alpine and subalpine zones and on steep, rocky slopes. However, the authors acknowledged that fire that does occur in subalpine and alpine habitats may create favorable mountain goat rangelands [37]. Other researchers reported that although fire occurred in mountain goat habitats, it had little influence on mountain goat populations. In 1964, Flook [38] noted that mountain goats used burned areas dominated by grasses and sedges in Banff and Jasper National Parks, Alberta, but concluded that "fire is of little importance in creating habitat" for this species. He considered most mountain goat rangelands to be perpetuated by climate or geological erosion rather than by fire. In 1977, Chadwick [21] observed that "recent" fires in Glacier National Park and the Swan Mountains disturbed some portions of mountain goat winter ranges but did not "appear to be a major influence" on mountain goat populations.
Fire may be detrimental to mountain goat populations in areas where mountain goats use mature forests for forage and cover. The effects may be particularly deleterious to winter ranges [16]. In southern interior and coastal mountain goat populations in British Columbia, fire was considered detrimental to mountain goats because it removed forage and snow-shedding tree canopies on winter ranges [60]. Boyd and others [16] agreed that fire in interior mountain goat winter ranges may be detrimental to mountain goat populations because sparse stands of trees and shrubs are used as forage and shelter from weather [16].
Although fire may increase some mountain goat forage species, it may decrease others. In Pacific Coast maritime forests, mountain goats consume salmonberry (Rubus spectabilis), which sprouts and grows rapidly in the first years after fire, although severe fires may reduce sprouting [91]. In the Red Butte Range of Montana, grouse whortleberry (Vaccinium scoparium) constituted 96% of the mountain goat winter diet and 49% of available vegetation [18]. Following low- or moderate-severity fires that do not kill the shallow rhizomes, grouse whortleberry sprouts quickly. Because the rhizomes occur in duff or at the duff-soil interface, severe fires can eliminate this shrub from a site [114,123]. For more information regarding fire effects on mountain goat forage, see FEIS reviews for species of interest.
Logging can have both positive and negative effects on mountain goats. Overstory removal can increase forage productivity in areas where fire exclusion has reduced the extent of open habitats. However, logging may reduce winter cover and loss of cover could increase snow depth locally, thus making forage unavailable in logged sites in winter [43,78,146]. Logging also increases human access to mountain goat habitat through road construction, and this has led to increased hunting mortality in some herds [20,78]. Except along travel corridors between ranges and to mineral licks, the effects of logging on mountain goat habitats may be restricted to areas within approximately 1,600 feet (500 m) of escape terrain [43].
Logging impacts may benefit mountain goats because of increased postlogging forage production. In the north-central Cascade Range, mountain goat forage abundance was greatest in clearcuts and least in forested habitats [45]. Because mountain goats foraged in clearcuts, clearcutting was suggested as a means of improving habitat for mountain goats in South Dakota [12]. Mountain goats also foraged in logged areas in south-coastal British Columbia in winter [130]. In Washington, they foraged in clearcuts when "sufficient" old-growth forest was left around the clearcut perimeter [78].
Logging impacts could be negative because of loss of forage and cover and because of disturbance and vulnerability resulting from increased human access [20,108]. High canopy cover in forests may benefit mountain goats by reducing snow depths on the ground and thus reducing mountain goat's energetic costs. Mature forests can be important sources of browse and lichens (see Diet). Forested buffers around escape terrain may also provide protection against disturbance [144]. Mountain goats that use low-elevation habitats in winter, such as those in coastal regions, may be most affected by logging [108,140]. In southeastern Alaska in winter, most (55%) mountain goats preferred forests with commercial timber (>8 thousand board feet (mbf)/acre), whereas only 5% of mountain goats preferred noncommercial forest stands (<8 mbf/acre), and no mountain goats preferred unforested areas [120]. Chadwick [20] found that mountain goats in western Montana either used logged areas less frequently than before logging or abandoned them completely.
Johnson [78] recommended that mountain goats have access to a variety of habitats to meet their needs. In coastal British Columbia, mountain goats commonly used old (>80 years) forests in winter, although some did not do so. Mountain goats often used early-seral forests (<40 years). Most (64%) early-seral forests used by mountain goats established after wildfires; the remaining early-seral forests established after logging (16%), site-preparation burning (4%), and unknown disturbances. Mountain goats spent the rest of their time in alpine habitats, particularly in large avalanche tracks. Because site fidelity was high in mature and old-growth forests, the authors recommended maintaining a high proportion of mature and old-growth forests in mountain goat winter ranges. Nonetheless, the authors suggested that logging small portions of mountain goat winter range through thinning or group selection may provide more abundant summer forage and more winter forage in low snowfall years, particularly on good snow-shedding areas [130]. In areas of extensive forests with cliff habitat in Washington, small clearcuts were considered beneficial for mountain goats, but a buffer of uncut forest was recommended to provide cover in cliff habitats with no overstory cover [78].
Several researchers recommended identifying key winter ranges, travel corridors, mineral licks, and birthing sites to protect the sites from logging activities; minimizing human-related disturbances, including logging, near mountain goat winter range; restricting logging to snow-free periods; closing logging roads to minimize access to mountain goat habitats; and maintaining logging rotations long enough to reestablish dense forest canopies and understories [16,78,99]. In southeastern Alaska, Fox [43] concluded that sites >1,600 feet (500 m) from escape terrain were mostly unused by mountain goats except during travel between wintering sites. Thus, direct effects of logging in areas >1,600 feet away from cliffs were considered restricted to factors that potentially change energy expenditures required during travel. These factors include large amounts of slash and increased snow depths in early-seral forests that could hinder movements [43]. Researchers recommended that forested travel corridors between wintering sites be kept intact because fragmented wintering habitat may concentrate mountain goats in habitat where they may be more vulnerable to gray wolf predation [99]. Johnson [78] also recommended avoiding mountain goat travel routes during logging. Fox [43] recommended leaving buffers of mature forest around travel routes in forests in southeastern Alaska to prevent snow accumulation along travel routes. In contrast, Boyd and others [16] recommended reducing conifer cover in forested travel corridors to enhance visibility for mountain goats and thus decrease predation risk. Poole and others [107] speculated that logging or burning areas around lick sites may either benefit mountain goats by opening habitat or, conversely, may cause mountain goats to abandon a lick due to loss of cover. Rice [109] suggested that land managers should make accommodations for high annual variability in habitat use within and among populations.
Population status: Mountain goats declined in much of their historic range due to overhunting following the arrival of European immigrants. In the mid-1900s, mountain goats were reintroduced in parts of their native range where they had been extirpated in Alaska, Idaho, Montana, Washington, and Alberta [24,34]. Throughout the 1900s mountain goats were also introduced in some areas outside of their known historical range: on Baranof, Chichagof, and Kodiak islands in Alaska; on the Olympic Peninsula in Washington; in the San Juan, Gore, and Collegiate ranges in Colorado; in the Wallowa Mountains in Oregon; in the Greater Yellowstone area of Montana and Wyoming and in other parts of central and south-central Montana; in parts of southern Idaho such as along the Salmon River; in the Black Hills region of South Dakota; in several mountain ranges in northeastern Utah; and in the Ruby Mountains, northeastern Nevada [24,34,89,110]. Mountain goats were introduced to these areas for trophy hunting [110].
Mountain goats introduced outside the species' native range have thrived on many sites because predators are absent, range conditions are good, and climates are relatively mild [24]. Introduced mountain goats in Olympic National Park affect native ecosystems by creating bedding and dust-bathing sites that disturb soil and vegetation over large areas and by changing the abundance and composition of plant communities by foraging on preferred species [102,116,117]. Because of their negative impacts on nonnative range in Olympic National Park, managers have attempted to reduce or eliminate mountain goat populations there [76]. According to a 2007 review, little is known about mountain goat's relationship to bighorn (Ovis canadensis), Kenai Dall (O. dalli kenaiensis), or Stone (O. dalli stonei) sheep in areas where both species are native, but some introduced populations of mountain goats are suspected to compete for forage or habitat with bighorn sheep populations [28,34].
Threats: Threats to mountain goat populations include overharvesting, particularly of females; increased human disturbance in formerly isolated habitats; reduction in forage quantity and quality because of successional changes in habitats from fire exclusion; habitat fragmentation due to human land uses, habitat succession, and climate change that may isolate populations; and tree removal in forested winter range (see Habitat management) [15,34,146]. To address these issues, Wisdom and others [146] recommended the following management practices: 1) reducing human activities in mountain goat habitats, particularly where mountain goat populations are static or declining, specifically by regulating the frequency and height of low-flying aircraft over mountain goat herds; 2) restoring quality and quantity of forage, where forage has declined because of successional changes, by thinning forest understories and using prescribed fire to improve forage and provide corridors between isolated herds; and 3) reducing fragmentation in historical ranges by maintaining connectivity among mountain goat habitats.
Human disturbance: Mountain goats are sensitive to human disturbance [24,34]. They may habituate to human disturbance in some areas, but where disturbance is unpredictable, mountain goats tend to be alarmed by disturbance [34,138]. Potentially adverse effects of disturbance on mountain goats included altered movements, range abandonment, increased vulnerability to predation, increased human access for hunting, and increased stress. High stress levels associated with disturbance have been suggested as a cause of decreased birth and recruitment rates and reduced winter survival in mountain goat populations. High stress levels may also cause a reduction in an individual's ability to fend off parasites, bacterial infections, and other diseases. Malnutrition and mineral deficiency—specifically selenium deficiency—can deleteriously affect mountain goats, especially when compounded by additional stresses [79,135,140].
A 1998 review of human disturbance on mountain goats concluded that human disturbance, such as aircraft and motor vehicle use, on mountain goat winter ranges is rare due to the steepness, ruggedness, and low snow accumulations of mountain goat winter habitats. However, the author noted that the use of helicopters, in particular, may pose a threat to mountain goat populations [138]. Helicopter recreation, helicopter logging, or fire control operations by aircraft may alter mountain goat behavior and time budgets [22,34,40,46,97]. Disturbance may be particularly detrimental in winter and during kidding [40,94,138]. Many researchers recommended a 1 mile (2 km) disturbance-free buffer around mountain goat habitat [22,34,40,138]. In Wenatchee National Forest, Washington, during a July lightning-caused wildfire, helicopters and fixed-wing aircraft maintained buffers of 500 feet (150 m) from birthing sites due to concerns that overflights would disturb mountain goats during kidding; no impacts were noted on mountain goats when this technique was used [97].
Mountain goat populations may be adversely affected by logging, road building, and mineral, coal, gas, and oil development [99,138]. Chadwick [20] found that mountain goats in western Montana either used logged areas less frequently than before logging or abandoned them completely. He found that mountain goats emigrated 3 miles (5 km) following disturbance from road building, and these mountain goats failed to return to disturbed sites 2 years after logging ended. Wright (1977 cited in [78]) reported that mountain goats on Barometer Mountain in the Cascade Range left their winter range and traveled to summer range early as a result of logging activity, but they returned to their winter range the following fall. In 1975, Rideout and Hoffman [110] reported that mountain goat populations in Idaho and Montana declined due to disturbance during and following road construction that resulted in increased human access. On Caw Ridge in Alberta, mountain goats abandoned a site while coal-mine exploration crews were working nearby [34]. In the Stikine River drainage, mountain goats abandoned summer ranges and relocated 1 to 2 miles (1-3 km) upstream after onset of hydroelectric exploration [40]. In the Sawtooth Range in northwestern Montana, declines in adult females and kids were associated with seismic activity caused by energy exploration in mountain goat habitat during 7 years (R= -0.85, P<0.05 for both variables) [79].
Succession: Mountain goats are "superb colonizers". They readily adapt to new habitats following transplants, and they readily colonize newly created habitats after disturbance [135]. Early-successional stages in forests and subalpine communities created by fire and other disturbances such as frequent, downslope movement of snow, ice, rocks, and water provide important mountain goat foraging sites [21,78]. Festa-Bianchet and Cote [34] surmised that mountain goats are well adapted to take advantage of disturbances where resource availability changes over time, citing the mountain goat's ability to twin when conditions are favorable and its strong tendency to disperse. The authors noted that mountain goat's life history strategy presents a "somewhat paradoxical mixture of traits" including those adapted to seral, frequently changing habitats (ability to twin, strong tendency to disperse) and those typical of species occupying very stable environments (late age of maturity, low reproductive effort) [34].
Mountain goats may rely on both primary succession (as a result of receding glaciers and snowfields) and secondary succession (as a result of fire, avalanches, and logging) to create suitable habitat [81,133,135,146]. Disturbances in alpine and subalpine habitats include frost heaving; wind blasting; extreme variation in snowpack; herbivory and associated trampling; avalanches; and fire. Subalpine grasslands burn occasionally, but since 80% to 90% of subalpine plant biomass is underground, fire does not affect the structure of subalpine grasslands greatly [94].
Drought periods in subalpine grasslands are associated with tree establishment. Typically, deep snow accumulates in meadows, and late snowmelt leaves meadows with a growing season too short for tree establishment, but extended drought (20 years) apparently allows for tree establishment.
In subalpine parklands, fire exclusion has contributed to changes in habitat structure and function. During wet climatic cycles, reduced fire frequency can lead to tree islands coalescing and parklands succeeding to closed forest. In subalpine parklands, fires are most likely to occur during dry periods on warm, dry southern aspects and steep slopes [5]. Fire in subalpine parklands may increase areas of alpine grassland [86]. Once burned, these sites are slowly reinvaded by trees [5] and become less suitable for mountain goats over time [94].
According to a 2000 review, mountain goats use all seral stages within forests except for the stem exclusion stage of montane and lower montane forests [146]. Mountain goat forage is abundant in early-seral forest, decreases in midsuccession, and increases again in late succession [43]. Mountain goats also use plant communities on ledges and fell fields that tend to be stable and self-perpetuating [21]. In the interior Columbia Basin ecosystem, declining mountain goat habitat in the Lower Clark Fork region was due to broad-scale, total loss of old-growth forests of ponderosa pine as well as declines in the stand initiation stage of lodgepole pine and Engelmann spruce-subalpine fir forests. In the Upper Clark Fork region, declines in mountain goat habitat were due primarily to loss of late-seral Douglas-fir and ponderosa pine forests [146].
Climate change: Because weather affects mountain goat population dynamics, global climate change may potentially affect mountain goat populations [15,34]. Global climate change is predicted to increase fall and winter precipitation in the range of mountain goats, resulting in greater snow accumulations. However, increased temperatures predicted by global climate change will probably result in more rain and less snow in winter, shorter duration of snow cover, a prolonged growing season, and an increase in the upper limits of plant growth as glaciers and snowfields recede [13]. As snowfields recede, food availability for mountain goats may increase [94,133], or conversely, food availability may decrease due to increased tree encroachment into subalpine and alpine habitats preferred by mountain goats [13,101,113]. Increased tree encroachment may fragment alpine habitats used by mountain goats. This could result in mountain goat populations becoming increasingly isolated from one another, making dispersal more difficult and individual herds becoming smaller and more vulnerable to losses from wildfires, severe winter weather, or diseases and parasites [93,94,133,135].
Mountain goats have distinctive white wool pelage [110] that is shed once each year [19,24,62]. Adult male mountain goats (billies) shed their coats first. They begin shedding in June, and molt is usually complete mid-July. Adult females (nannies) with young-of-the-year (kids) shed their coats later than nannies without kids, and yearlings are the last to molt, usually by mid-August [19,110]. Winter coat growth is complete in November or early December [24].
Mountain goats have black, recurved horns that are 8 to 10 inches (20-25 cm) long [110]. The horns of males are thicker and more curved than those of females. Horns grow longer and thicker as the animal ages. They are first visible on mountain goat kids in July [34].
Adult males are larger than adult females [34,35]. According to a review, adult body mass in midsummer ranges from 209 to 342 pounds (95-155 kg) for males and 132 to 165 pounds (60-75 kg) for females [24]. Mountain goats in northern parts of their range show greater differences in size between genders than those in southern regions [27]. Because of their larger body size, males may occupy areas with deeper snow than females [24,135]. See Growth for more information.
According to a review, there were an estimated 75,000 to 110,000 mountain goats in North America in 2003 [24]; about 33% occur in the United States [135].
According to a 1991 review, mountain goat densities range from 0.2 mountain goat/km² to 15.4 mountain goats/km² [89]. The highest mountain goat population density was reported on Running Rabbit Mountain in Glacier National Park, an area that was relatively wet and had numerous rocky outcrops and ledges at low elevation. The authors concluded that the highest mountain goat densities reported in published literature prior to 1985 were generally from expanding, introduced coastal populations; populations inhabiting environments with high precipitation; and populations inhabiting shallow snow areas with "suitable" size, slope, and distribution of rock outcrops and ledges [118]. In southeastern Alaska, southwestern Yukon, and northwestern British Columbia, the highest mountain goat densities occurred where precipitation was greatest [29].
Protective microsites such as caves are usually limited, and mountain goats compete for them. Dominant animals utilize the "best" microsites. In Idaho, subordinate animals moved into preferred sites after hunters removed dominant animals. Because the best microsites were apparently selected for their characteristics as shelter rather than for availability of forage, food was generally thought to be limiting to mountain goats at these sites [85].
Bedding and dust-bathing sites: Before lying down, mountains goats often dig bedding sites with their front hooves [24,110]. Bedding sites are used for resting and ruminating [19,20]. All individuals in a group usually use the same areas to bed [20,24]. Bedding sites are used repeatedly by different animals [19,24]. Continual use of bedding sites over many years denudes large areas of vegetation [17,20]. Mountain goats compete for individual bedding sites. According to a review, about 36% of all aggressive interactions among mountain goats occur at resting-ruminating sites, where mountain goats attempt to displace each other to occupy the "best" bedding sites (Cote unpublished data cited in [24]).
In summer, mountain goats use some bedding sites for dust-bathing [19,20,110]. Houston and others [74] commented that it is often not possible to distinguish between bedding and dust-bathing sites. Mountain goats select bedding sites near or in escape terrain with a view of the surroundings [17,19,20,24,146]. On hot days, they frequently bed in the shade or on snowbanks [17,19,20,110]. On Klahhane Ridge in summer, mountain goats bedded in rocky bluffs (25%), snow (24%), bare ground (21%), and open meadows (14%). Rocky bluffs were presumably preferred for bedding because of their escape value, snow and bare ground for their thermoregulatory value, and open meadows for resting between feeding bouts [126]. In the Swan Range, Montana, 95% of mountain goats bedded in cliff habitat year-round, specifically on upper portions of rock outcrops, often with steep cliff walls at their backs. Because summer bed sites were often used to dust bathe, summer beds were often on open hillsides with loose, dry soil remote from cliffs, whereas winter beds were usually beneath overhangs and sheltered from weather [20].
Birthing sites: Pregnant females isolate themselves from other mountain goats to give birth. Birthing sites or kidding areas are typically rocky outcrops or cliffs used as escape terrain [12,24,110]. They are usually on winter ranges and are used year after year [16]. On Mt Hamell in Alberta, use of rocky habitats increased during parturition [139]. Conversely, on Caw Ridge, only 30% of parturition sites were on cliffs, probably because of the limited availability of cliffs. Rather, most birthing sites were within 300 feet (100 m) of treeline, and some were in forests [34].
Lick sites: Mineral licks used by mountain goats provide sources of minerals (e.g., sodium, magnesium, and sulfur) and buffering compounds (carbonates and clays) important to mountain goat nutrition and digestion [8]. Licks used by mountain goats may occur naturally or be man-made [8,9,19,131]. Natural licks used by mountain goats may be dry-earth or wet licks, although mountain goats appear to prefer dry-earth licks [8,61,107].
Mountain goats use licks throughout the day and night [9] and throughout the year [107,111], with use peaking during spring and summer [8,9,17,61,111,126,131]. Males and females typically use licks with similar frequency [9,107], but males generally use licks earlier in the year than females with young [61,107,111]. In southeastern British Columbia, males began using licks in April, and females with young used licks in early June [61]. In another study in a different region of southeastern British Columbia, most males visited licks from early May to late June, and most females visited licks from early June to mid-July [107]. In Colorado, male mountain goats used man-made licks 2 weeks earlier than females [131]. Female lick use appears to be delayed by parturition [9,61].
Mountain goats frequently travel long distances from summer ranges in alpine habitats to reach licks, which are often at low elevation [107,110]. To access licks, they generally travel along traditional trails [107], which often traverse large forested areas. Mountain goats often use rocky bluffs within the forests, from which they make periodic excursions to lick sites [9,61,107]. In the East Kootenay region, mountain goats moved up to 10.7 miles (17.3 km) to visit licks [107]. In the Gore Range, Colorado, mountain goats traveled up to 8 miles (12 km) to access a lick [67]. Mountain goats may travel to licks multiple times each year [67,107,111]. Mountain goats in northern British Columbia traveled at least 2 miles (3 km) over 2,300 feet (700 m) elevation from their alpine foraging habitats to dry licks along streams or riverbeds that were close to steep, rocky bluffs and cliff banks [9]. In southeastern British Columbia in early spring through summer, mountain goats used high-elevation sites, feeding at and above treeline. They left these high-elevation areas beginning in May and traveled from 2 to 15 miles (3-24 km) to licks, passing through Douglas-fir forests to access low-elevation rocky bluff areas in the forests that occurred close to lick sites. Mountain goats often remained in the bluffs for several days, traveling repeatedly to the nearby lick sites [61].
When approached by a large mammalian predator, a mountain goat will remain in or move to steep and broken terrain [43]. Predation risk appears highest in forests or in krummholz, which provide cover for ambush predators [24,34]. On Caw Ridge, predation appeared to be the main cause of neonate and kid mortality, and most predation occurred in forests or in krummholz where some tree cover was present [35]. In Jasper National Park, mountain goats left crags and high grasslands and traveled "long distances" through forests to access dry mineral licks. Mountain goat kills were often found adjacent to the licks [26].
Most studies indicate that mountain goats select foraging sites close to escape terrain (e.g., [16,21,43,139]). On the Beartooth Plateau in northwestern Wyoming, mountain goats preferred areas <1,300 feet (400 m) from cliffs and avoided areas farther away [59]. On White Chuck Mountain, Washington, mountain goats preferred meadows, rocky benches, and chutes within 1,300 feet (400 m) of cliffs year-round [140]. In southeastern Alaska, 80% of annual mountain goat observations were within 1,300 feet (400 m) of cliffs [120]. Mountain goats in an introduced population in South Dakota spent most of their time (spring: 69%; summer: 65%; fall: 49%) on open slopes, meadows, and clearcuts that were within 160 feet (50 m) of granite outcrops [12]. In a canyon along Pinto Creek, Alberta, the size and number of cliffs within an area determined cliff use by mountain goats, with mountain goats preferring large cliffs grouped with other cliffs [57].
Mountain goats appear to make trade-offs between their competing needs for food and protection from predators [43,139]. Mountain goat forage availability tends to be highest in open, grassy areas where predation risk is high; food is relatively sparse on cliffs and rocky terrain, where security is highest [43,139]. Von Elsner-Schack [139] contended that food and safety for mountain goats occur on a continuum in which food increases with increasing grass cover and security increases with increasing rock cover. On Caw Ridge during summer, females spent 60% of their time foraging within 260 feet (80 m) of escape terrain. During most months of the summer (July-September), forage abundance at distances <260 feet from escape terrain was lower than forage abundance at distances >260 feet [50]. In southeastern Alaska, 75% of mountain goat observations in alpine habitat were in unproductive, steep and broken terrain, which was more than expected based upon availability (P<0.001). When proximity to escape terrain was taken into account by including only foraging sites within 160 feet (50 m) of escape terrain, Fox [43] found a positive correlation between available forage biomass above the snow and mountain goat habitat use (P<0.001). Mountain goats used the "best predator avoidance habitat" 77% of the time, the best food acquisition habitats near escape terrain 18% of the time, and the best habitats for thermoregulation the remaining time (6%). This indicated that predator avoidance was the most important determinant of mountain goat habitat selection, followed by food acquisition; thermoregulation was of minor importance [43].
Mountain goat use of habitats close to escape terrain varies according to predator abundance, individual gender, and group size (e.g., [43,47,108,139]). An introduced population in the Gore Range, Colorado, used habitats without escape cover. They had little access to escape terrain, with the nearest escape terrain 5 miles (8 km) away; large mammalian predators were absent from the area [67]. On Mt Evans, Colorado, where predator density was low, some mountain goats were observed >0.6 mile (1 km) from escape terrain, although most mountain goats were closer [47].
Males apparently are more tolerant of predation risk than females and therefore may have access to higher quality and/or quantity forage than females during spring and summer. Nursery bands rarely wander far from escape terrain or below treeline, whereas adult males often forage in conifer forests remote from escape terrain [6,24,34,130,135]. Females with young appear more reluctant to use habitat far from escape terrain than females without young [50,126]. On Caw Ridge in summer, male groups were seen in forested habitat 45% of the time, apparently taking advantage of abundant food resources in forests in summer, whereas nursery groups were seen in forested habitat only 9% of the time [34]. In June, when offspring were about 1 month old and particularly vulnerable to predation, females with young foraged an average of 70 feet (20 m) closer to escape terrain than females without young, but there was no difference in July, August, or September [50]. In the Sapphire Mountains, Montana, males were more mobile than females and often used habitat that was forested and lacked escape terrain, whereas females used open areas with escape terrain most often [111]. Near Haines, Alaska, male and female mountain goats occurred at similar elevations, but females used steeper slopes that were more rugged and closer to cliffs than males [141].
Small groups may use escape terrain more frequently than large groups. On Mt Hamell in Alberta, small groups (≤4 individuals) used escape terrain (gravel and rock habitats) more than large groups (>4 individuals). Large groups used grassy slopes, ridges, and alpine meadows most often when active but used rock habitats most often for resting. Small groups used grasslands and gravel areas equally when active and rock and gravel areas when resting. Small groups apparently used gravel habitats most because gravel habitats were located between grass and rock habitats, thus providing access to both food and escape terrain but not the best of either. This suggested that larger groups had increased security [139]. In the Sawatch Range, Colorado, group sizes were larger, and fewer mountain goats were solitary above treeline (mean group size: 10.4; solitary goats: 1%) than below treeline (mean group size: 3.1; solitary goats: 12%) [1]. On Klahhane Ridge, the largest groups (≥20 mountain goats) often occurred in open meadows distant from escape terrain [74]. Band size increases with population density (see Social behavior) [74]. This suggests that population density indirectly influences use of escape terrain.
Mountain goat foraging sites vary by season. Mountain goats shift habitat use in response to changes in food availability because of snow accumulation, moisture, wind, and solar exposure [146]. Typical foraging sites are open meadows near cliffs. In summer, nursery bands use all foraging sites that are close to escape terrain from treeline to the limit of vegetation. In winter, mountain goats of both genders are restricted to foraging sites near escape terrain at and just below treeline that are either windswept or on west- or south-facing slopes. Bachelor groups and solitary males may use forested areas near treeline throughout the year [24]. In the Crazy Mountains, Montana, the order of importance of habitat as year-round feeding areas to an introduced mountain goat population was grassy slide-rock slopes, ridgetops, alpine meadows, mixed-conifer forests, and cliffs [115]. On Klahhane Ridge in summer, mountain goats foraged mostly in open meadows (55%) and on scree or talus slopes (32%). Open meadows were most heavily used because they had the highest herbaceous cover of any available habitat [126]. In another study on the Klahhane Ridge during the snow-free period (May-November), mountain goats grazed most frequently in varileaf phacelia-edible thistle (Phacelia heterophylla-Cirsium edule) meadows on steep, erodible slopes (30-36°) with moderate (46%) plant cover; in varileaf phacelia-western yarrow (Achillea millefolium) meadows on very steep, active scree slopes (35-40°) with low (17%) plant cover; in black alpine sedge-showy sedge (Carex nigricans-C. spectabilis) turfs on stable soil in late-melting (late-June to late July) snow basins with high (73%) plant cover; in well-drained broadleaf lupine (Lupinus latifolius)-showy sedge associations on stable soil in late-melting snow basins with high (74%) plant cover; and in showy sedge-arnica (Arnica spp.) associations on a moist site at low elevation in a north-facing cirque with moderate (55%) plant cover [102].
Mountain goats exploit phenological differences among plants to obtain the most nutritious forage. They often move to low elevations in spring and seek green forage at high elevations in summer (see Elevation). They use different aspects, depending on timing of snowmelt and plant phenology. In spring, mountain goats feed in snow-free habitats on south aspects. As the summer progresses, mountain goats follow receding snow lines and the emergence of young, succulent vegetation to habitats on west aspects. By late summer to early fall, they use north and east aspects on steep, shaded ledges with melting snow (see Aspect) [16,137]. In spring in the Swan Range, Montana, mountain goats foraged mostly on south- and west-facing cliffs where vegetation, primarily grasses and sedges, was first exposed from snow. In summer, mountain goats moved among cliffs, meadows, and ravine-wet meadows, following vegetation green-up, particularly that of succulent forbs and shrubs. In fall, mountain goats concentrated foraging on bunchgrasses in dry meadows. In late fall and early winter, deep snow restricted mountain goats to cliffs where snow was shallow. In mid- to late winter, mountain goats increased use of snow-free ridgetops, although they continued to use cliffs where wind and steep terrain prevented deep snow accumulations [20].
In winter, mountain goats often select foraging sites to avoid deep snow. The influence of snow accumulation on mountain goats in alpine and low-elevation forest sites varies. Relative depths in alpine sites are largely wind determined, while those at lower elevations are most affected by conifer cover, slope, and aspect [43]. Conifer cover may benefit wintering mountain goats by intercepting and redistributing snow and providing access to browse and arboreal lichens [16]. Gilbert and Raedeke [45] summarized winter mountain goat habitat use by region and concluded that mountain goats in coastal regions occupy cliffs in dense forests, mountain goats in the Cascade Range occupy cliffs in clearcut and open forests, and mountain goats in interior regions occupy cliffs and nonforested ridges. Thus, in general, forests appear particularly important as foraging sites on winter ranges in coastal regions. Mountain goats in wet interior regions, where they occur year-round along river canyons and on cliffs interspersed among forests, may also benefit from conifer cover in winter (e.g., [17,20,43,45,57,60,108]). In southeastern Alaska, mountain goats used conifer forest on steep slopes with rock outcrops as winter range [96]. In north-central British Columbia, they used mature (141-250 years old) subalpine fir/interior white spruce forest with tall (>93.5 feet (28.5 m)) trees and high canopy closure (46-65%) during winter. In spring and summer, mountain goats used intermediate-aged (81-140 years old) forests with short (33.4-63.6 feet (10.5-19.4 m)) trees and moderate canopy closure (26-45%) [136]. At 3 sites near Ketchikan in southeastern Alaska in winter, they used sites with higher timber volume, at lower elevations, on steeper slopes, more southerly aspects, and shorter distances to cliffs than unused sites [122]. In the Stikine River drainage in northwestern British Columbia, mountain goats used rock habitats (33% of observations), open woodlands (28%), burns (24%), closed forests (13%), scrublands (2%), and grasslands (0.3%). Habitats with trees were important for cover, particularly in winter; burns for foraging, particularly in spring and fall; and rock habitats for escape terrain year-round [40].
Conversely, conifer habitats may collect more snow than other available habitats and thus not be used by mountain goats. In the Sawatch Range, Colorado, mountain goats in alpine areas preferred fell-field, turf, meadow, marsh, and rock habitats, which were also the most abundant habitats above treeline. Rock habitats included cliffs, outcrops, scree, talus, and boulder fields. Other available habitats above treeline—willow, sparse conifer (<50% canopy cover), and dense conifer (>50% canopy cover) stands—tended to collect snow and were not used by mountain goats [1]. Increased risk of predation may also limit mountain goat use of dense conifer forests, although mountain goats often use sparse conifer stands [16].
Snowfall may not be the overriding influence in mountain goat habitat use in some areas. In the north-central Cascade Range, mountain goats used open habitats such as clearcuts, open forests, and wooded cliffs in winter, and habitat use did not appear to be related to snowfall patterns [45]. In the East Kootenay region of interior British Columbia, mountain goats wintering in areas of deep, moist snowfall did not use mature forest stands more frequently than mountain goats in areas of shallow, dry snow, even though snow depths in the shallow-snow area averaged about 60% of depths in the deep-snow area [108].
Because of the mountain goat's preference for habitats close to escape terrain, some researchers have concluded that mountain goats showed no apparent preference for any habitat as long as it occurred on steep terrain or near cliffs and talus [146]. On the Klahhane Ridge, there was no relationship between forage production and mountain goat grazing intensity or frequency. Instead, mountain goats preferred meadows close to rocky outcrops regardless of availability of preferred forage species [102]. At Caw Ridge, mountain goats did not select sites according to seasonal differences in forage biomass or peak forage protein during a 2-year study. Consequently, dispersion of nursery bands could not be explained by local differences in forage quality or quantity (Haviernick 1996 cited in [34]). Mountain goats in east-central Idaho appeared to select winter habitat primarily for its slope and snow-shedding ability and not for the availability of forage [85]. Other researchers contended that mountain goats make trade-offs between their competing needs for food and protection from predators [43,139]. For more information on this topic, see Escape terrain.
Socially subordinate individuals may be forced to use less preferred foraging sites. Overt aggressive behavior toward subordinates increases in winter when resources are limited and declines in summer when resources are abundant [74]. In the Pahsimeroi River drainage in Idaho, dominant adult females excluded subordinates from the "best" winter feeding sites (i.e., steep cliffs with shallow snow) [77]. In the Bitterroot Mountains, Montana, socially dominant adult females occurred on snow-free cliff ledges, while subordinates were on "less optimal" habitat [119]. In western Montana, the level of aggression between males and females increased when males and females were concentrated on winter range. This apparently resulted in adult males avoiding the "best" wintering areas [111]. Dominant animals also exclude subordinates from preferred sheltered microsites [85] and bedding sites [24]. Kids and older offspring associated with dominant nannies have access to foraging areas, bedding sites, sheltered microsites, and salt licks with their mothers, whereas orphaned kids or solitary young are subject to high intraspecific aggression at these sites [20,39,77,95]. As a result, the presence of a mother is hypothesized to increase survival of kids, although orphaned kids can survive [39,111].
Mountain goats use habitat habitually, and trail systems in forests between cliffs are important linkages between mountain goat habitats. Within a canyon along Pinto Creek, Alberta, mountain goats traveled between cliffs using a network of trails in lodgepole pine and white spruce forests and riparian habitats [57]. In Jasper National Park, mountain goats left crags and high grasslands and traveled "long distances" through forests to access dry mineral licks [26]. Cite (personal observation cited in [24]) reported that when mountain goats crossed forested valleys, they typically used traditional and well-marked trails. For more information on this topic, see Habitat management.
Mountain goats may travel though unusual habitats during migration between summer and winter ranges, during dispersal, and to visit mineral licks. In the Red Butte Range in northwestern Montana, mountain goats were occasionally observed moving through burned areas with abundant windfalls and snags, dense stands of timber, and lowland valleys between ranges where there was no escape terrain [17]. Williams [142] documented mountain goat dispersal across 2.5 miles (4 km) of prairie habitat from an introduced population on Square Butte, an isolated volcanic formation in the prairies of central Montana. Klein [83] stated that bodies of water several miles across, extensive ice fields, and broad timbered valleys were barriers to mountain goat movements in Alaska [83]. However, in the Kenai Mountains, Alaska, mountain goats crossed large ice fields and major drainages when migrating between summer and winter ranges [98]. Rideout [111] reported that mountain goats swim across large rivers and lakes.
The gestation period ranges from 147 to 186 days [24,99,110]. Most kids are born from mid-May to early June [24,110,139]. Mountain goats were born as early as late February [19] and as late as late August [21] in Montana, possibly indicating recurrent estrus [21,34]. According to a 2003 review, about 80% of kids are born within a 2-week period [24]. On Caw Ridge, 80% of kids were born within a 17-day period [34].
As parturition approaches, pregnant females isolate themselves from other mountain goats to give birth [24], although occasionally a previous year's offspring may accompany a parturient female to the birthing site [34]. A female remains with her kid at the birthing site until the kid can follow her. Kids are precocial [110] and can stand and nurse within about 45 minutes [34]. Within 2 to 3 days, a kid can follow its mother [24]. After approximately 2 weeks of seclusion, nannies and kids form groups (see Social behavior) [135].
Kids can eat vegetation at 1 week old [20,24] and are weaned at about 4 months old. Young remain with their mothers until the following spring when the mother gives birth again [24,110]. For more information on mother-offspring associations, see Social behavior.
Growth: Mountain goats weigh approximately 5.5 to 7.7 pounds (2.5-3.5 kg) at birth [24,99,110]. Male and female kids weigh the same. Weight gain during the first summer is similar between males and females, averaging 0.43 pound (0.20 kg)/day. Sexual dimorphism in body mass develops after weaning, increasing gradually up to at least 6 years old. As yearlings, males are about 10% heavier than females. At ≥5 years old, males are about 40% to 60% heavier than females. A review stated that females may reach maximum body size at 6 years old, whereas males may continue to increase in mass with age [24].
Age at first reproduction: Females and males are sexually mature at 18 months, but it is rare for mountain goats to reproduce this young in the wild [20,24,70]. In the wild, females may first reproduce at 30 months old [10,24,44,110], although most females first reproduce at 42 or 54 months old [10,24]. Age at first reproduction in female mountain goats <54 months old is most common in expanding, introduced populations such as those in Washington [71] and Colorado [10]. Some females introduced into the Olympic Mountains apparently conceived at 18 months old, although most bred at 30 or 42 months old [72]. In a native population on Caw Ridge, females <54 months old did not reproduce; 29% of females produced their first kid at 54 months old; and most females reproduced at 66 months old [35]. Festa-Bianchet and Cote [34] stated that in ungulates in general, primiparity (giving birth for the first time) does not occur at a set age but occurs at the age when females reach approximately 80% of their peak body mass. However, the association between nanny body mass and age of primiparity was weak in the Caw Ridge population [34]. Houston and others [70] reported that on Klahhane Ridge in Olympic National Park, all females that were ≥3 years old and weighed >110 pounds (50 kg) were lactating, whereas those <110 pounds were not. Reproductive senescence in females apparently occurs after they are 13 years old [34]. See Frequency of reproduction for more information.
Males may first reproduce at 18 or 30 months old [20,24,44,110], but most males <42 months old do not reproduce [20,92]. On Caw Ridge, only males ≥54 months old mated [92]. In the Swan Range, Montana, 30-month-old males mated in a population where adult sex ratios were highly skewed towards females, and some nanny groups had no males present during the rut. However, males >30 months old mated most often [20].
Pregnancy and twinning rates: Usually nannies give birth to single kids; up to 33% of births are twins, and triplets are rare [24,110]. Researchers suggested that twinning is more common in introduced and rapidly growing populations than in established and stable populations [24]. An increasing native population in the Stikine River drainage, British Columbia, averaged 18% twins during 1 year [40]. An increasing population of mountain goats introduced along the Snake River, Idaho, about 12 years prior to the study, had twinning rates ranging from 25% to 33% over 2 years [58]. In a native population on Caw Ridge, where nutrient availability apparently limited mountain goat reproduction, 2% of mountain goat births were twins during 5 years [35]. An introduced population on Klahhane Ridge had a mean twinning rate that was lower at high density (2.1%) than at low density (12.4%) over 10 years (P<0.05) [72]. Mountain goats apparently take advantage of favorable environmental conditions by increasing reproductive output. This suggests that the number of offspring may be related to resource availability [24].
Frequency of reproduction: Mountain goats do not reproduce every year. According to a 2000 review of mountain goats in British Columbia, up to 40% of mature females in a given year may not produce any offspring [14]. In the Coast Ranges of southwestern British Columbia over 33 years, the percent of females breeding annually was 4% to 10% when the herd was static or declining and 68% when the herd was increasing [30]. On Klahhane Ridge, production of kids over 5 years ranged from 0.2 kid/year (1 kid in 5 years) to 1.2 kids/year [72]. On Caw Ridge during 18 years, adult females reproduced in about 25% of years [52]. In years when a female did not reproduce she was more likely to care for her yearling, but extended maternal care did not appear to improve yearling growth or survival [34].
The frequency of reproduction and the number of kids produced by a nanny increase with her age, social rank, and previous reproductive effort. According to a 2003 review, kid production increases with maternal age during the first few years following primiparity, remains stable until about 10 years old, and declines thereafter [24]. On Caw Ridge, the percent of females giving birth increased for 3- to 6-year-old nannies, peaked at 81% for 8- to 12-year-old nannies, then declined to 67% for older nannies [34]. On Sheep Mountain-Gladstone Ridge, Colorado, maximum female reproductive output for an introduced population occurred from 4 to 9 years old (66%) and declined for females ≥10 years old (53%) [10]. Kid production also increases with nanny social rank. On Caw Ridge, females that were dominant for their age had higher probability of producing a kid than subordinate females of the same age [34].
Female mountain goats may have a lower probability of reproducing in a given year if they reproduced the previous year, particularly if they are young and in poor condition or population density is high. Hamel and others [52] reported that low-quality females (light weight, socially subordinate) on Caw Ridge had a lower probability of reproduction if they had reproduced the previous year than if they did not (P<0.001), whereas high-quality females showed no cost of successive reproduction. Young females had a lower probability of reproduction if they had bred the previous year than if they did not, whereas older females showed no effect of previous parturition. Young females bear the cost of growth and reproduction simultaneously, which may explain why young females had lower probability of reproduction. At low population density, previously breeding and nonbreeding females had similar probability of reproducing; however, at high density, the probability of reproduction was 25% lower for previously breeding than for previously nonbreeding females. Apparently, at low population density, reduced competition allowed females to compensate for the high energetic costs of reproduction [51].
Sex ratios: Kid sex ratios in mountain goats may be skewed due to differential production or mortality. On Klahhane Ridge, the kid sex ratio in midsummer was 38% male. The authors hypothesized that the scarcity of male kids may have indicated either greater production of female kids by nannies or higher mortality of male kids [73]. Conversely, in the Sapphire Mountains, Montana, Rideout [111] observed more male than female kids. Kid sex ratio on Caw Ridge was apparently affected by maternal age. During a 14-year study, the percent of daughters decreased from 59% for mothers ≤6 years to 38% for mothers ≥10 years. The authors hypothesized that males may be more costly to wean than females due to their larger body size, and that young mothers may be less able to support male kids due to their need to bear the cost of their own growth as well as reproduction. However, the authors found no evidence that sons were costlier to wean than daughters, and there was little sexual dimorphism in kid mass prior to weaning [34].
Adult sex ratios in mountain goats range from close to parity to skewed towards females because of higher male mortality [24,110]. A 1975 review reported adult sex ratios ranging from 23% to 87% male [110]. Populations near East Kootenay in southern interior British Columbia (60% males) [60] and Glacier National Park in western Montana (53% males) [111] reported adult sex ratios skewed towards males in populations with no or light hunting pressure. In the Swan Mountains, Montana, adult male:adult female ratios were low after 2 severe winters (27-33% males) and increased after a mild winter (55% males), suggesting that severe winters affected the survival of males more strongly than females [20].
Groups of mountain goats within a herd are commonly referred to as "bands". Bands may consist of >100 individuals (Cote 1999 cited in [24]). Bands appear to consist of "loosely associated, interchanging individuals" [21]. Band composition and size vary between activity, season, habitat, population density, and individual age, gender, and social status [24,99]. Typically, adult males and adult females are segregated into separate bands except during the summer at mineral licks and during and after the rut, when males and females are concentrated on winter ranges [24,111]. A "unique" population in Glacier National Park was not segregated by gender [118].
Adult females form nanny groups or nursery bands with kids and 1- and 2-year-olds of both genders [24]. Nursery bands usually average about 4 to 5 individuals, but many increase to 15 to 20 or more after kidding [14]. Nursery bands are smallest in spring during the kidding period, when gravid females isolate themselves from most other mountain goats to give birth [17,67,135]. Females start to form nursery bands after 1 week of parturition in early June. By July, nursery bands attain peak size [67]. Adult males are solitary or form bachelor groups, typically consisting of 2 to 6 individuals [14,24]. In spring, bachelor groups are often larger (≤15 individuals) than other times because young males (≥2 years) often split from nursery bands and join bachelor groups [20,24,34,135]. Band size is often largest when males and females are concentrated on winter ranges. In 2 native populations in western Montana, mountain goat bands tended to join together in winter, possibly to take advantage of mountain goat trails that provided access to forage in deep snow [19]. In an introduced population in the Crazy Mountains, Montana, mountain goat groups tended to be small (<10 individuals) overall, but groups tended to be largest (up to 40 individuals) in winter when range was limited [90]. For more information on this topic, see Home range.
Mother-offspring groups are the most common aggregation and persist after weaning and the birth of a new kid. On Caw Ridge, yearlings commonly associated with their mothers, and occasionally older offspring (2- and 3-year-olds) remained closely associated with their mothers. Females without a kid present were most likely to associate with their older offspring [34]. Nannies generally do not tolerate close proximity of unrelated young [19,34]. On Caw Ridge, although adult females preferentially associated with related young, they did not appear to preferentially associate with related adults. Thus, mountain goat bands consisted of both related and unrelated individuals [34]. Adult females associated more often with adult females of similar social rank than with individuals that were distant in the dominance hierarchy [23].
Nursery band in Jasper National Park, Canada. Photo courtesy of Joy Viola, Northeastern University, Bugwood.org.In general, group size tends to increase with population density. On Klahhane Ridge, mean group size in June was positively associated with June population size (r²=0.88, P<0.05) during 5 years [74]. Group composition may also be influenced by population density. On Running Rabbit Mountain in Glacier National Park, mountain goats were not sexually segregated. Rather, both genders utilized the same feeding areas and ledges, and were frequently observed in mixed-gender groups. The authors proposed that the high population density (mean annual group size: 24 mountain goats), small home range, and/or potentially abundant food resources may have forced a closer non-rut association of genders than observed in other populations [118].
Mountain goat groups may be more efficient at detecting potential predators than single individuals. In mountain goats, individual vigilance decreased as group size increased to at least 10 to 15 individuals [64,112]. Bachelor groups are small and occur more often in closed habitats such as forests than nursery groups, which are large and most often occur in open habitats (see Preferred Habitat). Males may accept a higher risk of predation to obtain more or better food than females because of their larger body size [34]. Females may be more vulnerable to attacks by large mammalian predators than males because of their smaller body size and association with young [141].
Mountain goat bands have well-developed dominance hierarchies based on individual size, strength, and age [14]. Dominance is achieved via antagonistic vocalizations and threat displays [74,110]. Dominant individuals are frequently older and larger than subordinates [23,74]. Dominance between genders may vary among populations [74]. In some locations, such as the Olympic Mountains [111], large adult males seemed to be dominant over females; however, in other populations, such as northern British Columbia [44], females appeared to be dominant over males [74]. Rideout [111] proposed that differences in dominance among studies appeared related to differences in food resources, with females increasing aggression and attaining dominance in areas of limited summer food. Socially subordinate individuals may be forced to use less preferred habitats. See Forage site selection for more information on this topic.
Survival of mountain goats follows the general mammalian pattern of higher mortality for juvenile and senescent individuals and relatively low mortality for prime-aged individuals [121]. Male survival is generally lower than female survival [24].
Mortality is highest among neonates and kids. After 2 years of study, Smith [119] estimated that 67% to 71% of kids survived to 1 year old in the Bitterroot Mountains, Montana. In an introduced population near Buena Vista, Colorado, the mean number of kids that survived for at least 3 to 6 months ranged from 52% to 69% [10]. On Caw Ridge, survival of kids during 13 years was 87% to weaning and 64% to 1 year old. Variability in kid survival among years was high (38-92%). Survival was greater for males (92%) than females (85%) to weaning, but there was no gender difference in kid survival to 1 year. Kids that survived to 1 year tended to be heavier (30.6 pounds (13.9 kg)) in mid-July than those that did not survive (28.0 pounds (12.7 kg)) to 1 year [34].
Survival of mountain goat yearlings is intermediate between that of kids and adults [24]. In the Bitterroot Mountains, survival of yearlings during 2 years averaged 84%; survival of males ≥2 years old was 82%, and survival of females ≥2 years old was 87% [119]. On Caw Ridge, survival of yearlings during a 13-year period was high (males: 74%, females: 85%). Survival of females 2 to 7 years old averaged 92%, and survival of females 10 to 16 years old averaged 76% [34]. In coastal Alaska near Ketchikan, annual survival was 71% for yearlings; 95% for 2- to 8-year-olds (included hunting mortality, 99% if hunting mortality was excluded); and 68% for ≥9-year-olds (none of which was due to hunting) [121].
Weather: Severe weather causes mountain goat mortality. In Glacier National Park, kid mortality was 41% and yearling mortality was 44% after a severe winter, but kid mortality was 27% and yearling mortality was 15% after a mild winter [21]. In the Sapphire Mountains, Montana, mortality during a severe winter was 73% for kids and 59% for yearlings, while during a mild winter, mortality was 27% for kids and 2% for yearlings [111]. Total population declines of 82% to 92% occurred following severe winters in coastal British Columbia (Hebert and Langin 1982 cited in [135]). Wadkins (1967 cited in [78]) correlated mortality rates with snowpack on Nason Ridge in Washington and found that above-average snowpack was correlated with a 40% loss of kids and a complete loss of yearlings.
Kid production appears to be negatively associated with winter severity and spring snow conditions, particularly in increasing populations [2,67,78,128,129]. Several researchers in Idaho, Montana, and Alaska found lower age ratios (kids:older animals)—a measure of reproductive success—after severe winters. Their studies suggest high in-utero or neonatal losses due to severe winter weather [17,21,63,111,119]. In an increasing introduced population in the Sawatch Range of Colorado, Adams and Bailey [2] found a negative correlation between summer age ratios (kids:older animals) and previous spring (1 May) snow depths at high elevation during 13 years (P<0.10). However, a subsequent study of the same population covering 24 years reported that the correlation did not persist after the population stabilized. Although previous spring snow depths were not related to mountain goat summer age ratios over the 24-year period, snow depth 2 springs prior to birth was positively related to mountain goat summer age ratios (R²=0.69, P=0.01) [10]. During a 5-year study of an introduced population on Klahhane Ridge, a positive relationship was found between reproductive rate and total winter precipitation 2 winters prior to birth (r=0.93, P<0.05) [127]. The amount of snow 2 winters or springs prior to birth may possibly affect the quality and/or availability of forage prior to ovulation [10,127]. During 6 years of below-average snow depth in the Sawtooth Range of northwestern Montana, there was no correlation between snow depth and kid:older animal ratios; thus, low snow depths apparently had little effect on kid survival [79]. While there are hazards in interpreting reproductive success from kid:adult ratios [34], this information may allow detection of large differences in reproduction [78].
Spring snow depth influences the timing of snowmelt and the initiation of vegetation growth. Late snowmelt likely increases mountain goat mortality, particularly of juveniles and senescent individuals, because it prolongs the period during which individuals must rely on stored fat. Year-to-year differences in the initiation of vegetation growth in spring likely affect the growth and survival of neonates because mothers are unable to produce sufficient milk when feeding on low-quality winter forage [34]. Low natality rates inferred from low kid:adult female ratios (about 40 kids:100 females) in the Bitterroot Mountains, Montana, were attributed to severe winter weather and delayed spring green-up [119]. On Caw Ridge during an 18-year study, cohorts born in years of high vegetation productivity, representing early springs, were of higher quality (body mass, social rank, and longevity) than cohorts born in years of low vegetation productivity, representing late springs. This suggests that kids born in years with early springs may benefit from early access to high-quality forage [54]. Conversely, a subsequent study on Caw Ridge found that the probability that kids would survive to weaning was lower when spring was early than when it was late [51].
Early springs may allow predators better access to mountain goat habitat during the first weeks after birth, when offspring are most vulnerable to predation, thus increasing offspring mortality [51]. Klein [83] reported that mountain goats in southeastern Alaska were most susceptible to predation in spring following kidding and in winter when snow was deep.
Mountain goat density and forage availability may affect mountain goat kid production and survival. On Caw Ridge, offspring survival during summer decreased with increased mountain goat population density: when density was about 1.8 times higher, survival was about 10% lower [51]. In an increasing population on Caw Ridge, a 13-year study found that kid survival (r=0.72, P=0.005) and population growth rate (r=0.61, P=0.26) were both positively correlated with the mass of yearling males, suggesting that yearlings were small and kids were less likely to survive in years when forage resources were fewer or of poor quality. No such relationships occurred with yearling female body mass, possibly because summer body mass gain was 25% faster for males than females. The authors surmised that forage availability and quality affected population growth, which was mostly independent of mountain goat density [34]. On Caw Ridge, kid mortality was low from February to May (close to 0%), suggesting that low food abundance in winter did not substantially contribute to kid mortality [35].
Solitary mountain goat in early September, Boulder Pass, Glacier National Park, Montana. Photo courtesy of Robin J. Innes, US Forest Service.
The mountain goat (Oreamnos americanus), also known as the Rocky Mountain goat, is a hoofed mammal endemic to mountainous areas of western North America. A subalpine to alpine species, it is a sure-footed climber commonly seen on cliffs and ice.
Despite its vernacular name and both genera being in the same subfamily (Caprinae), the mountain goat is not a member of Capra, the genus that includes all other goats, such as the wild goat (Capra aegagrus), from which the domestic goat is derived. Instead, it is more closely allied with the takins (Budorcas) and chamois (Rupicapra).
The mountain goat is an even-toed ungulate of the order Artiodactyla and the family Bovidae (along with antelopes, gazelles, and cattle). It belongs to the subfamily Caprinae, along with true goats, wild sheep, the chamois, the muskox and other species. The takins of the Himalayan region, while not a sister lineage of the mountain goat, are nonetheless very closely related and almost coeval to the mountain goat; they evolved in parallel from an ancestral goat. Other members of this group are the bharal, the true goats, and the Himalayan tahr. The sheep lineage is also very closely related, while the muskox lineage is somewhat more distant. The mountain goats probably diverged from their relatives in the late Tortonian, some 7.5 to 8 million years ago.
Given that all major caprine lineages emerged in the Late Miocene and contain at least one but usually several species from the eastern Himalayan region, their most likely place of origin is between today's Tibet and Mongolia or nearby. The mountain goat's ancestors thus probably crossed the Bering Strait after they split from their relatives, presumably before the Wisconsinian glaciation. No Pliocene mountain goats have been identified yet; the known fossil record is fairly recent, entirely from North America, and barely differs from the living animals. In the Pleistocene era, the small prehistoric mountain goat Oreamnos harringtoni lived in the southern Rocky Mountains. Ancient DNA studies suggest that this was the sister species of the living mountain goat, not its ancestor; consequently, the living species would also date back to the Pleistocene at least.[2][3]
The mountain goat is the only living species in the genus Oreamnos. The name Oreamnos is derived from the Greek term ὄρος óros (stem ore-) meaning "mountain" (or, alternatively, oreas "mountain nymph") and the word ἀμνός amnós meaning "lamb".
Both male and female mountain goats have beards, short tails, and long black horns, 15–28 cm (5.9–11 in) in length, which contain yearly growth rings. They are protected from the elements by their woolly greyish white double coats. The fine, dense wool of their undercoats is covered by an outer layer of longer, hollow hairs. Mountain goats molt in spring by rubbing against rocks and trees, with the adult billies shedding their extra wool first and the pregnant nannies shedding last. Their coats help them to withstand winter temperatures as low as −46 °C (−51 °F) and winds of up to 160 kilometres per hour (99 mph).
A male goat stands about 1 m (3.3 ft) at the shoulder to the waist and can weigh considerably more than the female (around 30% more in some cases). Male goats also have longer horns and longer beards than females. Male mountain goats are typically larger, stronger, and heavier than females and have a longer beard than the females. The head-and-body length can range from 120–179 cm (47–70 in), with a small tail adding 10–20 cm (3.9–7.9 in).[4][5][6]
The mountain goat's feet are well-suited for climbing steep, rocky slopes with pitches exceeding 60°, with inner pads that provide traction and cloven hooves that can spread apart. The tips of their feet have sharp dewclaws that keep them from slipping. They have powerful shoulder and neck muscles that help propel them up steep slopes.[7] Based on a field recording in the Rocky Mountains of Canada of a mountain goat climbing a 45-degree slope, researchers were able to measure the goat's whole body movement as it climbed. Researchers observed that when the goat propelled itself forward, it extended its back legs and the front legs were tucked close up to its chest during its first phase. During the second phase, the goat raised its back legs near to its chest, while the front leg's humerus stayed locked in a persistent location relative to the goat's chest, therefore allowing the elbow to be detained in close proximity to the whole body's center of balance. Extension of the elbow and carpal joints resulted in a vertical translation of the center of mass up the mountain slope.[8]
The mountain goat inhabits the Rocky Mountains and Cascade Range and other mountain regions of the Western Cordillera of North America, from Washington, Idaho and Montana through British Columbia and Alberta, into the southern Yukon and southeastern Alaska. British Columbia contains half of the world's population of mountain goats. [9] Its northernmost range is said to be along the northern fringe of the Chugach Mountains in south-central Alaska. Introduced populations can also be found in such areas as Idaho, Wyoming, Utah, Nevada, Oregon, Colorado, South Dakota, and the Olympic Peninsula of Washington.
Mountain goats are the largest mammals found in their high-altitude habitats, which can exceed elevations of 13,000 ft (4,000 m). They sometimes descend to sea level in coastal areas although they are primarily an alpine and subalpine species. The animals usually stay above the tree line throughout the year but they will migrate seasonally to higher or lower elevations within that range. Winter migrations to low-elevation mineral licks often take them several kilometers through forested areas.[10]
Daily movements by individual mountain goats are primarily confined to areas on the same mountain face, drainage basin, or alpine opening. Daily movements reflect an individual's needs for foraging, resting, thermoregulation and security from predators or disturbance. Seasonal movements primarily reflect nutritional needs (such as movements to and from mineral licks/salt lick), reproductive needs (in other words, movement of pre-parturient females to "kidding" areas; movement to rutting areas), and climatic influences (including movement to areas in response to foraging conditions). In general, seasonal movements are likely to exhibit a strong elevational component, whereby lower, forested elevations are used during the spring-summer (security cover effects) to access lower elevation mineral licks, and during winter (thermal cover effects) to access forage. The farthest movements are expected to be by dispersing mountain goats. Such movements are likely to involve mountain goats crossing forested valleys as they move between mountain blocks.
Mountain goats are herbivores and spend most of their time grazing. Their diets include grasses, herbs, sedges, ferns, mosses, lichens, and twigs and leaves from the low-growing shrubs and conifers of their high-altitude habitat.
In captivity, the mountain goat's diet can also include grain, alfalfa, fruits, vegetables and grass.
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In the wild, mountain goats usually live 12 to 15 years, with their lifespans limited by the wearing down of their teeth. In zoos, however, they can live for 16-20 years.
Mountain goats reach sexual maturity at about 30 months.[11] Nannies in a herd undergo synchronized estrus in late October through early December, at which time females and males participate in a mating ritual. Mature billies stare at nannies for long periods, dig rutting pits, and fight each other in showy (though occasionally dangerous) scuffles. Nannies often ignore young billies, who try to participate but are discounted in favor of older partners. Both females and males usually mate with multiple individuals during breeding season, although some billies try to keep other males away from certain nannies. After the breeding season is over, females and males move away from each other. Nannies form loose-knit nursery groups of up to 50 animals. The adult billies leave, often alone or with two-three other billies.
Kids are born in the spring (late May or early June) after a six-month gestation period. Nannies give birth, usually to a single offspring, after moving to an isolated ledge; post partum, they lick the kid dry and ingest the placenta. Kids weigh a little over 3 kg (6.6 lb) at birth and begin to run and climb (or attempt to do so) within hours. Although lactation is mostly finished at one month, kids follow their mothers closely for the first year of life (or until the nanny gives birth again, if this does not occur the next breeding season); nannies protect their young by leading them out of danger, standing over them when faced by predators, and positioning themselves below their kids on steep slopes to stop freefalls.
Nannies can be very competitive and protective of their space and food sources. They fight with one another for dominance in conflicts that can ultimately include all the nannies in the herd. In these battles, nannies circle each other with their heads lowered, displaying their horns. These conflicts can occasionally lead to injury or death, but are usually harmless. To avoid fighting, an animal may show a posture of nonaggression by stretching low to the ground.
In regions below the tree line, nannies use their fighting abilities to protect themselves and their offspring from predators. Predators, including wolves, wolverines, lynxes, and bears, attack goats of most ages given the opportunity. The cougar, or mountain lion, is perhaps the primary predator, being powerful enough to overwhelm the largest adults and uniquely nimble enough to navigate the rocky ecosystem of the goats. Though their size protects them from most potential predators in higher altitudes, nannies must sometimes defend their young from both bald and golden eagles,[12] which can be a predatory threat to kids.[5] Nannies have even been observed trying to dominate the more passive, but often heavier bighorn sheep that share some of their territory. In 2021, a mountain goat gored a grizzly bear to death in Yoho National Park, British Columbia.[13]
Mountain goats introduced in the 1920s into Washington’s Olympic Mountains were in time found to be a nuisance there, in particular while seeking human urine and sweat for its salt content, the park lacking natural salt licks, and even aggressively approaching human visitors. One such goat killed a hiker in 2010.[14] Officials finally chose to eradicate them from the Olympic Peninsula, removing hundreds, mostly by capturing them and relocating them to the Cascade Mountains.[15]
Although mountain goats have never been domesticated and commercialized for their wool, pre-Columbian indigenous peoples of the Pacific Northwest Coast did incorporate their wool into their weaving by collecting spring moulted wool left by wild goats.[16]
The mountain goat (Oreamnos americanus), also known as the Rocky Mountain goat, is a hoofed mammal endemic to mountainous areas of western North America. A subalpine to alpine species, it is a sure-footed climber commonly seen on cliffs and ice.
Despite its vernacular name and both genera being in the same subfamily (Caprinae), the mountain goat is not a member of Capra, the genus that includes all other goats, such as the wild goat (Capra aegagrus), from which the domestic goat is derived. Instead, it is more closely allied with the takins (Budorcas) and chamois (Rupicapra).
