Blue-headed vireo
Blue-headed vireo | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Aves |
Order: | Passeriformes |
Family: | Vireonidae |
Genus: | Vireo |
Species: | V. solitarius
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Binomial name | |
Vireo solitarius (Wilson, 1810)
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The blue-headed vireo (Vireo solitarius) is a
As the name suggests, the blue-headed vireo is characterized by its blue-grey head and bold yellow wing bars. Both sexes are very similar in plumage and size. Juveniles also have a similar plumage.
Populations of the blue-headed vireo have been steadily increasing since the 1970s. Therefore, in 2004, the species was classified as a "
Description
The blue-headed vireo has similar plumage year round and does not drastically change its appearance during the breeding season. It can be characterized by its olive green upper body, two bold yellow wing bars down the edge of its wing, and a deep blue-grey crown from which it gets its name. The juvenile plumage of immature blue-headed vireos is not distinct but very similar to the adult plumage.[3] While this bird's appearance is similar to the closely related Cassin's vireo (Vireo cassinii), the Cassin's vireo can be differentiated by its lighter yellow patches, a smaller, thinner bill, and a brownish-grey crown.[4] There is little to no sexual dimorphism between males and females as both are similar in plumage colouration and size.[5]
Like most Vireos, the blue-headed vireo is a relatively small bird with a length of 126–148 mm (5.0–5.8 in). The wingspan is usually found to be around 200–240 mm (7.9–9.4 in) and their weight is typically 13–19 g (0.46–0.67 oz). There are some subtle differences between the V.s. solitarius and V.s. alticola subspecies. V.s. alticola, the larger of the two subspecies, has a darker back with a larger wing length of 76–83.5 mm (2.99–3.29 in) and a bill length of 11–12 mm (0.43–0.47 in). Conversely, V.s. solitarius is slightly smaller with a wing length of 69.2–77.8 mm (2.72–3.06 in), and a bill length of 8.9–11 mm (0.35–0.43 in).[3]
The average lifespan of the blue-headed vireo in the wild has been measured to be approximately 7 years and 5 months.[3]
Taxonomy
The blue-headed vireo is placed in the
Though it had been previously classified as a separate species, the blue-headed vireo along with the
There are two recognized subspecies of blue-headed vireo:[6]
- Vireo solitarius solitarius – (Wilson, A, 1810) – is the nominate species. It is slightly smaller and breeds across Canada to south Pennsylvania and New Jersey. It overwinters in north-central and southern Mexico.[3]
- Vireo solitarius alticola – Brewster, 1886 – is slightly larger than the nominate species. It breeds mainly in the
Habitat and distribution
Native to North America, the blue-headed vireo enjoys a large breeding range that extends over an immense area of Canada and northern United States. The breeding range of V.s. solitarius extends from northeastern British Columbia across Alberta, Saskatchewan, Manitoba, Ontario and Quebec and down to southern Pennsylvania and New Jersey. V.s. alticola has a distinct breeding range that includes western Maryland and south, mainly in the Appalachian Mountains, to northern Georgia. At the end of the breeding season, the blue-headed vireo migrates south to its overwintering area. V.s. solitarius has the longest migration of the two subspecies and inhabits an overwintering area that includes eastern and southern Mexico to northern Central America. V.s. alticola migrates across a shorter distance to an area that extends from southeastern Virginia to Texas.[3]
Blue-headed vireos prefer to breed in cool temperate forests, which in the southern part of its breeding range are found at higher elevations. Evergreen forests with
Year round, even during the breeding season, population density is somewhat low and spread out. Overwintering population densities are usually found to be lower than in the breeding season.[8] The density of the population ultimately depends on the type of forest being inhabited.[3]
During migration, blue-headed vireos are often found to flock with groups of different sparrow species but rarely with members of its own species.[3]
Habitat loss
When blue-headed vireos arrive on their breeding grounds, typically in mid-April, many deciduous trees have yet to leaf out, leading them to nest in evergreen trees including hemlocks (Tsuga). Recently, however, many hemlocks in eastern USA have been killed by an invasive Asian insect, the Hemlock woolly adelgid (Adelges tsugae), leaving the vireos with fewer nesting options until spring leaf opening begins for deciduous trees.[9]
Behaviour
Vocalizations
The primary song of the blue-headed vireo is a simple, slow, monotonous tune that is often confused with the faster
When foraging during the breeding season, mated pairs constantly communicate with each other using a series of high pitched chirping calls.[3][10]
Diet
Blue-headed vireos are mainly
Reproduction
When arriving to the breeding ground in mid-April, male vireos will hold large, individual territories that can range from 1.5–6.6 hectares (3.7–16.3 acres). Females will choose a male to mate with depending on the male's ability to defend and control a large territory. While defending their territory from other males, the male vireos will sing a primary song to attract females.[13] Undecided females can usually be seen flying along the edges of competing male territories; usually this will force the two males into direct conflict for the right to copulate with the female.[10][13]
Once a female has approached a suitable mate, the male will perform a series of mating rituals. Typically, these rituals involve the male building a courtship nest for the female. The courtship nest is not a full nest but is most likely an attempt by the male to display his ability to gather resources.[10][13] Once the pair is established, the courtship nest is abandoned. Mating does not occur for approximately 2 weeks after pair has been established. During this time, the male and the female will cooperatively build a breeding nest which is typically formed between forking mid-level branches of evergreen and deciduous trees and are composed of twigs and foliage. Breeding nests are not reused in following breeding seasons.[3]
In one breeding season, a female will lay 3–5 eggs at a rate of 1 egg per day. Eggs are creamy white with brown or black spots and are 17–23.1 x 13.3–15.8 mm (0.055–0.075 in x 0.04–0.05 in). Eggs are
Blue-headed vireo's have an atypical breeding strategy when compared to other closely related species. Blue-headed vireo males will assist their mates with daytime incubation of eggs, nest construction, and feeding of the chicks.
Hormonal effects on parental care
The increase in male blue-headed vireo parental care is thought to be attributed to the levels of
Predation
Blue-headed vireos have a low nesting success rate, with about 10–30% of hatchlings surviving.
Often, when a nest is attacked by a blue jay, the male and female will execute coordinated attacks on the approaching predator. This usually involves one partner swooping towards the blue jay while calling the mate who will then execute a second attack.[10] Blue-headed vireos have also been known to nest close to nesting raptorial birds that do not prey on them. It is thought that they use the raptors as protection from squirrels that are, in turn, hunted by these bird of prey.[3]
The largest contributor to the low nesting success rate of the blue-headed vireo is most likely the parasitic brown-headed cowbird (Molothrus ater). These birds will often lay their large eggs overtop the existing brood, causing the parents to feed the cowbird which will ultimately starve the infant Vireos.[3]
References
- . Retrieved 12 November 2021.
- ^ Brauning, D. W. (1992). Atlas of breeding birds in Pennsylvania. Pittsburgh, PA: University of Pittsburgh Press. p. 484.
- ^ a b c d e f g h i j k l m n o p q r James, R. D. (1998). The Birds of North America. Philadelphia, PA: The Birds of NA, Inc.
- ^ Phillips, A. R. (1991). The known birds of North America, Part II. Denver, Colorado: Allan R. Phillips. p. 249.
- ^ The Wilson Bulletin. 70 (4): 307–346.
- ^ S2CID 25941327.
- JSTOR 1365441.
- ^ Hamel, P.B. (1992). Land manager's guide to the birds of the south. Chapel Hill, NC: The Nature Conservancy. p. 367.
- S2CID 42295889.
- ^ .
- ^ "Blue-headed Vireo". Audubon. Retrieved 2024-04-22.
- ^ Petit, L.J.; Petit, D.R.; Petit, K.E.; Fleming, W.J. (January 1990). "Annual variation in foraging ecology of prothonotary warblers during the breeding season". The Auk. 107: 146–152.
- ^ doi:10.1139/z78-160.
- ^ Wingfield, J.C.; Ball, G.F.; Dufty, A.M. Jr.; Hegner, R.E.; Ramenofsky, M. (1987). "Testosterone and aggression in birds". American Scientist. 75 (6): 602–608.
- .
- ^ Buntin, J.D. (1996). Neural and hormonal control of parental behavior in birds. New York: Academic Press. pp. 161–213.
- ^ S2CID 1651743.
- S2CID 27464874.
External links
- Blue-headed Vireo – Vireo solitarius – USGS Patuxent Bird Identification InfoCenter
- Blue-headed Vireo Species Account – Cornell Lab of Ornithology
- Blue-headed vireo photo gallery at VIREO (Drexel University)
- Blue-headed Vireo: A Migratory Bird with Sexual Equality? – Smithsonian Migratory Bird Center
- Blue-headed Vireo Life History at birdzilla.com
- "Blue-headed vireo media". Internet Bird Collection.
- Interactive range map of Vireo solitarius at IUCN Red List maps