Eastern bluebirds eat a variety of foods depending on the season. In summer months, eastern bluebirds consume mostly beetles (order Coleoptera), crickets, caterpillars, grasshoppers, and other insects. A United States Biological Survey study of 855 eastern bluebirds found that the bluebird diet was 68% insects. During the fall and winter seasons, when insects are less common, eastern bluebirds eat fruits and plants, including blackberries, honeysuckle, dogwood, red cedar, and wild grapes.
Eastern bluebirds drink water from ponds, streams and birdbaths. They appear to prefer running water versus standing water.
Animal Foods: insects
Plant Foods: seeds, grains, and nuts; fruit
Primary Diet: carnivore (Insectivore )
Eastern bluebirds influence the composition of insect communities through their predation on insects. They also host many species of parasites, including mites, lice and blowflies.
Eastern bluebirds affect communities of the insects they eat. They also provide habitat for many species of parasites, including mites, lice and blowflies.
Eastern bluebirds may help to control insect populations.
Positive Impacts: controls pest population
There are no known adverse affects of eastern bluebirds on humans.
The future of eastern bluebirds has been of concern to conservation agencies. Population numbers have dropped drastically in the last few decades (in some places by as much as 90%), although recent increases in numbers have been encouraging. As a result, eastern bluebirds have been given some level of protection throughout their range. Two major hypotheses have been proposed to explain the decline, they are habitat destruction and competition. Much of the eastern bluebird's habitat has been turned into farmland or commercial property, greatly reducing food and shelter resources. Eastern bluebirds also compete with the more aggressive, introduced species, house sparrows and European starlings, for food and nesting sites. The most effective measure implemented to protect eastern bluebirds has been the introduction of nest boxes placed in good nesting habitat for bluebirds. These boxes are relatively easy to make and maintain and have been quite successful in places where they have been established.
Eastern bluebirds are listed as a species of "least concern" by the IUCN. They are not protected under CITES or the U.S. Endangered Species Act. There are an estimated 10,000,000 eastern bluebirds in North and Central America.
US Migratory Bird Act: protected
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
Eastern bluebirds communicate primarily through sounds. One of the most distinguishing characteristics of this species, aside from its distinctive coloring, is its song. Bluebirds have different songs for mating, territoriality, and other purposes. When heard, the most common call of the bluebird sounds like -chir wi- or -chur lee-. When repeated several times, the call resembles the words -truly- and -purity-. Eastern bluebirds also use visual cues to communicate.
Communication Channels: visual ; acoustic
Perception Channels: visual ; tactile ; acoustic ; chemical
This species is the state bird of both Missouri and New York. Several other common names have been used to denote this bird, including American bluebird, Wilson's bluebird, Common bluebird, and others. In addition to S. sialis, there are two other species of bluebirds: Sialia mexicana (Western bluebird) and Sialia currucoides (Mountain bluebird). Both of these birds species have coloration and habits similar to that of S. sialis. Their ranges differ, although some range overlap occurs in the mid-west and central parts of the United States. Several cases of albinism have been seen within S. sialis, and hybrid crosses between Sialia species have been conducted, some of which were successful.
This species has a very broad range. It is found east of the Rocky Mountains, spanning from southern Canada to the Gulf states and on into Mexico and Honduras. There are also populations found in Cuba, although it is not a native species there.
Biogeographic Regions: nearctic (Native )
Eastern bluebirds prefer open land with scattered trees for perching, nesting, and feeding. They are often seen in parks, gardens, hedges, and other areas that provide perches. They are also commonly found sitting on fences and utility wires.
Habitat Regions: temperate ; tropical ; terrestrial
Terrestrial Biomes: savanna or grassland
Other Habitat Features: suburban ; agricultural
Eastern bluebirds can live up to 6 to 10 years. The oldest known wild individual lived 10 years and 5 months. However, most mortality occurs in the first year of life, making average lifespans much shorter than this.
Range lifespan
Status: wild: 10.4 (high) years.
Average lifespan
Status: wild: 125 months.
Eastern bluebirds are small birds with short, slender beaks and short legs. They are brightly colored, with a blue upper body, red breast, and white abdomen. Males have wing and tail feathers that are blue with black or gray shafts and tips. Their heads are a lighter shade of blue, which fades into a red throat and breast area. The breast and belly are white with light blue tips on some of the longer feathers. Females also exhibit this pattern of coloration, although they tend to be duller than males and have more gray. Adult weight ranges from 27 to 34 grams. They are, on average 18 cm long from the tip of their beak to the end of their tail.
Young bluebirds are grayish in color. They have speckled breasts and their wings are tipped in blue. The blue color becomes much more prominent and the speckles on their breast disappear as they become adults.
There are eight recognized subspecies of Sialia sialis. These subspecies are distinguished based on coloration and geographic range.
Range mass: 27 to 34 g.
Range length: 16 to 21 cm.
Average length: 18 cm.
Other Physical Features: endothermic ; bilateral symmetry ; polymorphic
Sexual Dimorphism: female larger; sexes colored or patterned differently; male more colorful
Eastern chipmunks and flying squirrels prey on eastern bluebird eggs and nestlings. House sparrows, European starlings, American kestrels black rat snakes, black racers, fire ants, domestic cats, black bears, and raccoons are predators of adults and chicks.
When approached by a predator, male eastern bluebirds make a song-like warning cry. If a male is not present, a female will begin to sing, hoping to attract a protective male back to the territory. Both males and females will also flick their wings and warble when predators are nearby.
Known Predators:
Eastern bluebirds are generally monogamous. However, some studies have shown that more than one female or male are involved in some broods, suggesting that monogamy is not always the rule in this species. Occasionally, juveniles of a first brood remain near the nest to help the parents raise a second brood. This behavior is uncommon among eastern bluebird. Juvenile helpers are much more common among western bluebirds.
Mating System: monogamous ; cooperative breeder
Mating occurs in the spring and summer months. A mature female will typically raise two broods each season. Nests are constructed in trees within abandoned woodpecker holes or other cavities that provide adequate protection (usually several feet above ground). Construction of the nest is done primarily by the female and takes approximately 10 days to complete. These nests are small, cup-like structures that are lined with grass, feathers, stems, and hairs. Each female lays 3 to 7 (average 4 to 5) light-blue or, rarely, white eggs. The female incubates the eggs, which hatch after 13 to 16 days. The young are altricial at hatching. Fledglings leave the nest 15 to 20 days after hatching. Several studies have revealed that some young will stay around the nest to help raise another brood.
Both parents cooperate in raising the young, which they feed a diet insects. Fledglings are grayish in color with a speckled breast. The blue color becomes much more prominent and the speckles on their breast disappear as they mature. Bluebirds may begin breeding the summer after they are hatched.
Breeding interval: A mature female typically raises two broods each season.
Breeding season: Eastern bluebirds breed in the spring and summer.
Range eggs per season: 3 to 7.
Range time to hatching: 13 to 16 days.
Range fledging age: 15 to 20 days.
Average age at sexual or reproductive maturity (female): 1 years.
Average age at sexual or reproductive maturity (male): 1 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous
Average eggs per season: 4.
The young are altricial, meaning they cannot care for themselves upon hatching. Both parents cooperate in raising the young. The female broods the chicks for up to 7 days after hatching. Both parents feed the chicks while they are in the nest and for about three weeks after they have left the nest. The chicks are fed mainly insects.
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Protecting: Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Female); pre-independence (Provisioning: Male, Female)
A small (7 inches) thrush, the male Eastern Bluebird is most easily identified by its deep blue head and back, red breast, and white belly. Female Eastern Bluebirds are similar to males, but are a duller gray-blue on the head and back. This species is unmistakable across much of its range, but Western Bluebirds (Sialia mexicana), which occur in southern Arizona and as vagrants on the western Great Plains, are of similar size and color. The Eastern Bluebird breeds across much of the eastern United States and southern Canada. In winter, northerly-breeding populations migrate to the southern U.S. and northern Mexico, while southerly-breeding populations are non-migratory. Other non-migratory populations exist in Mexico and Central America, one of which extends north into extreme southern Arizona. Eastern Bluebirds historically inhabited variety of open woodland habitats. In modern times, this species has expanded into human-altered environments such as orchards, shrubby agricultural fields, and large yards in suburban areas. Eastern Bluebirds primarily eat fruits, berries, and small invertebrates. In appropriate habitat, Eastern Bluebirds may be observed flying down to the ground from perches in pursuit of prey. In many areas during the breeding season, this species is most easily located by looking for pole-mounted nest boxes in open areas: wherever these nest boxes are found, there are likely Eastern Bluebirds around. This species is primarily active during the day.
A small (7 inches) thrush, the male Eastern Bluebird is most easily identified by its deep blue head and back, red breast, and white belly. Female Eastern Bluebirds are similar to males, but are a duller gray-blue on the head and back. This species is unmistakable across much of its range, but Western Bluebirds (Sialia mexicana), which occur in southern Arizona and as vagrants on the western Great Plains, are of similar size and color. The Eastern Bluebird breeds across much of the eastern United States and southern Canada. In winter, northerly-breeding populations migrate to the southern U.S. and northern Mexico, while southerly-breeding populations are non-migratory. Other non-migratory populations exist in Mexico and Central America, one of which extends north into extreme southern Arizona. Eastern Bluebirds historically inhabited variety of open woodland habitats. In modern times, this species has expanded into human-altered environments such as orchards, shrubby agricultural fields, and large yards in suburban areas. Eastern Bluebirds primarily eat fruits, berries, and small invertebrates. In appropriate habitat, Eastern Bluebirds may be observed flying down to the ground from perches in pursuit of prey. In many areas during the breeding season, this species is most easily located by looking for pole-mounted nest boxes in open areas: wherever these nest boxes are found, there are likely Eastern Bluebirds around. This species is primarily active during the day.
The eastern bluebird (Sialia sialis) is a small North American migratory thrush found in open woodlands, farmlands, and orchards.
The bright-blue breeding plumage of the male, easily observed on a wire or open perch, makes this species a favorite of birders. The male's call includes sometimes soft warbles of jeew or chir-wi, or the melodious song chiti WEEW wewidoo.[2] It is the state bird of Missouri[3] and New York.[4]
The eastern bluebird was formally described by the Swedish naturalist Carl Linnaeus in 1758 in the tenth edition of his Systema Naturae under the binomial name Motacilla sialis.[5] The type location is South Carolina.[6] Linnaeus based his short Latin description on the earlier more detailed descriptions by the English naturalists Mark Catesby and George Edwards.[7][8] The eastern bluebird is now placed in the genus Sialia that was introduced by the English naturalist William John Swainson in 1827 with the eastern bluebird as the type species.[9][10]
Seven subspecies are recognised:[10]
Eastern bluebirds measure 16–21 cm (6.3–8.3 in) long, span 25–32 cm (9.8–12.6 in) across the wings, and weigh 27–34 g (0.95–1.20 oz).[12][11]
Male bluebirds have a bright head, back, and wings. Their breast is a brownish red.[12] Females are lighter with gray on the head and back and some blue on their wings and tail. In females, the breast is usually lighter in color than in males, and is more orange.[12]
The eastern bluebird is found east of the Rockies, southern Canada to the Gulf states, and southeastern Arizona to Nicaragua. The increase in trees throughout the Great Plains during the past century due to fire suppression and tree planting facilitated the western range expansion of the species.[13] as well as range expansions of many other species of birds.[14][15][16] From 1966-2015 the eastern bluebird experienced a greater than 1.5% annual population increase throughout most of its breeding and year-round ranges, with exceptions including southern Florida and the Ohio River valley.[17]
Bluebirds tend to live in open country around trees, but with little understory and sparse ground cover. Original habitats probably included open, frequently burned pine savannas, beaver ponds, mature but open woods, and forest openings. Today, they are most common along pastures, agricultural fields, suburban parks, backyards, and even golf courses. Populations also occur across eastern North America and south as far as Nicaragua. Birds that live farther north and in the west of the range tend to lay more eggs than eastern and southern birds.[18]
An isolated, insular subspecies of the eastern bluebird is found on Bermuda, and has a distinctive, brighter blue coloration compared to mainland populations. This population was formerly thought to have been predated the colonization of the islands (making it one of only three extant, resident pre-colonization Bermuda landbirds, alongside the Bermuda white-eyed vireo and gray catbird). However, analysis of fossil strata found no evidence for the existence of bluebirds on the islands prior to European colonization. Using simulations and molecular evidence, a 2013 study found that the Bermuda bluebirds likely descend from very small founder population from a single colonization event during the 1600s. This colonization event could either be a natural one by migratory individuals or an anthropogenic introduction by early settlers, who are known to have introduced several other eastern North American birds like the northern cardinal (Cardinalis cardinalis) to Bermuda very shortly after colonization. It is likely that the alteration to the islands' ecosystem due to the clearing of native forest facilitated this colonization by providing optimal bluebird feeding habitat, along with a lack of predators.[19][20]
Eastern bluebirds are social, and will sometimes gather in flocks of over a hundred. However, they are territorial during the breeding season and may continue to defend a feeding area throughout the winter.
Mating occurs in the spring and summer. A mature female typically raises two broods each season. Nests are constructed in trees within abandoned woodpecker holes or other cavities that provide adequate protection (usually several feet above ground). Construction of the nest is done primarily by the female and takes around 10 days to complete. These nests are small, cup-like structures lined with grass, feathers, stems, and hairs. Each female lays three to seven light-blue or, rarely, white eggs. The female incubates the eggs, which hatch after 13 to 16 days. The young cannot care for themselves upon hatching. The female broods the chicks for up to seven days after hatching. Fledglings then leave the nest 15 to 20 days after hatching.[11]
Both parents cooperate in raising the young, which they feed a diet consisting almost entirely of insects. Some young stay around the nest to help raise another brood. Fledglings are grayish in color, with speckled breasts. The blue color becomes much more prominent and the speckles on their breasts disappear as they mature. Bluebirds may begin breeding the summer after they are hatched.[11]
Eastern bluebirds can live for 6 to 10 years. The longest recorded lifespan for a bluebird is 10 years and five months.[18] However, most bluebirds die within their first year of life. Starvation and freezing are a danger to the young, but most threats come from other animals, including humans. Natural predators of eggs and nestlings can include eastern chipmunks, flying squirrels, American black bears, fire ants, and raccoons. Bluebirds of all ages (including adults) are threatened by rat snakes, racers, American kestrels, and domestic cats. Introduced species such as European starlings and house sparrows are competitors for nesting sites. Non-nesting adults face predation by all native species of falcons, owls, and most varieties of hawks, particularly those in the genus Accipiter. When approached by a predator, the male makes a song-like warning cry. If no male is present, a threatened female will begin to sing, hoping to attract a protective male back to the territory. Both males and females also flick their wings and warble when predators are nearby.[11]
About two thirds of an adult bluebird's diet consists of insects and other invertebrates. The remainder is made up of wild fruits or berries. It has a preference for grasshoppers, crickets, katydids, and beetles; and will also eat earthworms, spiders, millipedes, centipedes, sowbugs, and snails.
Bluebirds feed by perching on a high point, such as a branch or fence post, and swooping down to catch insects on or near the ground. The availability of a winter food source will often determine whether or not a bird will migrate. If bluebirds do remain in a region for the winter, they group and seek cover in heavy thickets, orchards, or other areas in which adequate food and cover resources are available.
Eastern bluebirds thrived in the 1700s and 1800s. This flourishing is thought to be connected with the activity of settlers. Clearing forests made new habitat available for bluebirds and nesting sites were created in the increasing numbers of apple orchards and in wooden fence posts that eventually rotted.[21] It is believed that bluebirds were most abundant around 1900. However, increasing competition with the invasive species of European starlings (Sturnus vulgaris) and house sparrows (Passer domesticus) along with loss of farmland began to take a toll on bluebird populations.[21] Along with these, pesticides and scarcity of food during winter compounded to cause the number of bluebirds to fall.[22] A definite drop has been shown to have occurred between 1938 and the late 1970s.[21]
Conservation efforts are seen as early as 1934 when Thomas Musselman created the first bluebird trail by setting up rows of bluebird houses along roads.[21] Also in the 1930s, William Duncan created a bluebird house design and educated others about these birds.[21] In 1964, The National Association for Protection and Propagation of the Purple Martin and Bluebirds of America was founded. After it went out of existence, the Nature Society kept up with conservation work.[21] Lawrence Zeleny's 1976 book, The Bluebird: How You Can Help Its Fight For Survival, and a National Geographic article he wrote helped make the plight of these birds well known.[21] In 1978, the North American Bluebird Society was founded.[21]
If the Bermuda population of bluebirds is considered the product of natural colonization, it has also become highly endangered. Early settlers described individual flocks numbering over 50 birds each flying across the islands, but in the present only 500 individuals are thought to remain. The near-extinction of Bermuda cedar (Juniperus bermudiana) forest in the 1940s and 1950s wiped out the majority of natural nesting habitat for bluebirds, leaving it almost completely dependent on artificial nest boxes for breeding. Introduced starlings and house sparrows evict bluebirds from their nests, and introduced great kiskadees (Pitangus sulphuratus) feed on juvenile birds. They are also threatened by feral cats and pesticides.[20]
Bluebirds were popular with early American colonists and associated with the coming of spring. They were referred to as the 'blue robin' because of their resemblance to the European robin.[22] Bluebirds have been mentioned in the works of many writers including Thoreau's writings, Robert Frost's "The Last Word of a Bluebird (as told to a child)", the "Over the Rainbow" song from The Wizard of Oz, the song "Zip-A-Dee-Doo-Dah" ("Mister Bluebird's on my shoulder") from Disney's Song of the South,[23] and John Burrough's "The Bluebird".[21] Lawrence Zeleny said that bluebirds represent joy to Americans.[22]
_at_nesting_box.jpg)
{{cite book}}: CS1 maint: multiple names: authors list (link) The eastern bluebird (Sialia sialis) is a small North American migratory thrush found in open woodlands, farmlands, and orchards.
The bright-blue breeding plumage of the male, easily observed on a wire or open perch, makes this species a favorite of birders. The male's call includes sometimes soft warbles of jeew or chir-wi, or the melodious song chiti WEEW wewidoo. It is the state bird of Missouri and New York.
