Black-throated blue warbler
Black-throated blue warbler | |
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Male | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Aves |
Order: | Passeriformes |
Family: | Parulidae |
Genus: | Setophaga |
Species: | S. caerulescens
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Binomial name | |
Setophaga caerulescens (Gmelin, 1789)
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Range of S. caerulescens[1] Breeding range Wintering range
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Synonyms | |
Dendroica caerulescens |
The black-throated blue warbler (Setophaga caerulescens) is a small passerine bird of the New World warbler family. Its breeding ranges are located in the interior of deciduous and mixed coniferous forests in eastern North America. Over the cooler months, it migrates to islands in the Caribbean and Central America. It is very rarely found in western Europe, where it is considered to be a non-indigenous species. The black-throated blue warbler is sexually dimorphic; the adult male has a black face and cheeks, deep blue upperparts and white underparts, while the adult female is olive-brown above and light yellow below.
Predominantly insectivorous, the black-throated blue warbler supplements its diet with berries and seeds in winter. It builds its nests in thick shrubs and the closeness of its nesting sites to the ground make it a favored species for the study of warbler behavior in the wild. The black-throated blue warbler defends its territory against other birds of the same species for both nesting and winter habitats. As the black-throated blue warbler requires large, unbroken forest areas for nesting, its numbers are declining.
Taxonomy and phylogeny
The German naturalist Johann Friedrich Gmelin described the black-throated blue warbler in 1789. Its species name is the Latin adjective caerulescens meaning "turning blue".
The black-throated blue warbler is one of the New World warblers or wood-warblers in the family
The species breeds in North America and winters in the Caribbean. Some studies have observed significant differences in terms of migratory behavior and plumage color between northern and southern populations within the breeding range.[4] The northern population mainly winters in the western Caribbean (Cuba and Jamaica) while the southern population usually spends the winter on eastern islands (Hispaniola and Puerto Rico). Moreover, males in the southern population have darker plumage than those in the northern population. These differences have led biologists to consider them as separate subspecies. However, a recent study in the United States reveals no significant genetic differentiation between northern (samples from Michigan, New Hampshire and New York states) and southern populations (sample from North Carolina).[5] The study results actually show a recent population expansion from a single glacial refugium, therefore the current populations are homogeneous in terms of genetics. The differentiation that is observed between the northern and southern populations should have occurred quite recently.[5]
Description
The black-throated blue warbler measures 13 cm (5.1 in) in length and weighs 8.4–12.4 g (0.30–0.44 oz).
The bird's
Distribution and habitat
The black-throated blue warbler is a migratory species. It breeds in temperate mature
Behavior
Feeding and foraging
The black-throated blue warbler forages actively in low vegetation, sometimes hovering or catching insects in flight. It often forages in one area for a while before moving on to the next. It mainly eats invertebrates such as caterpillars, crane flies, and spiders. It may supplement its diet with seeds, berries, and fruit in the winter.[8]
Males and females prefer different foraging sites. While males usually hover among the higher shrub foliage between 3 and 9 m (9.8 and 29.5 ft), females tend to forage at lower strata.[11] The time within a breeding season influences where the males forage. When it is time to feed the fledglings, males come down to the same foraging strata as females. The black-throated blue warbler mostly forages in the understory instead of the canopy.[13] The large leaves and long branches in the understory affect its foraging behaviors. The black-throated blue warbler more often hovers rather than gleans its prey because it is more difficult to glean among thick understory foliage.[13]
Breeding
The black-throated blue warbler is a monogamous species.[14] Its breeding season usually begins in May and ends in July.[15] As a songbird, the male black-throated blue warbler attracts a female's attention by singing a soft melody. He then follows the female while she is foraging or searching for nesting sites. As soon as the female stops to rest, the male droops his wings slightly, stretches his head forward and up, opens his bill, and faces the female. The female also makes displays to the male by vibrating her wings. In response, the male mounts the female for 2–3 seconds and then flies off.[10]
A 1996, researchers showed that the black-throated blue warbler prefers to reside in
The black-throated blue warbler uses social cues in its evaluation and choice of nesting sites.[15] In particular, it listens to the post-breeding songs given out by other males. These songs have strong temporal dependencies. Males sing at the beginning and the peak of breeding season, but songs are not indicative of reproductive success. Near the end of a breeding season, a male that has successfully mated continues to sing while a male that has failed to reproduce abandons the habitat. Therefore, post-breeding songs are reliable indicators of reproductive success within the particular habitat and convey essential information to the natal and breeding dispersers. In comparison to the traditional idea of direct assessment of the vegetation structure, the vocal cue is much more efficient and easier to obtain, hence revealing the advantage of social communication in survival and reproduction. A female, however, does not respond to post-breeding songs directly. Instead, she is likely to rely on the presence of males in deciding nesting sites.[15]
Extra-pair mating
Although the black-throated blue warbler is a socially monogamous species, males are frequently observed in territories of other males, suggesting the occurrence of extra-pair matings.
Males engage in mate guarding during the period females are most vulnerable to successful extra pair copulations. They usually stay close to their social mate, singing slowly on the side and following the mate while she is foraging or searching for a nesting site.[10] The guarding behavior, though, may conflict with males' pursuit of extra-pair fertilizations. It is not yet clear to what extent a male will prefer mate guarding over extra-pair fertilizations.[14] Male retention studies have shown that removal of a male increases the chance of extra-pair offspring in the brood, suggesting that mate guarding reduces extra-pair fertilization attempts.[17] The extra-pair fertilization rate nonetheless cannot be eliminated even if males are allowed to stay near their social mates during fertility risk period. Several hypotheses try to explain this phenomenon: females may be able to manage extra-pair mating even while its social mate is guarding it, or females may reject extra-pair copulation attempts by other males in the absence of male guarding.[17]
Females who participate in extra-pair fertilizations may incorporate better genes in their offspring than they could get with their social mate, but they are likely to receive less help with parental care from their social mates because of cheating. Extra-pair fertilization, therefore, can be costly to females as well.[19] A possible theory why extra-pair fertilization occurs is that female organisms select males with overall high heterozygosity or dissimilar genetics from themselves.[20][21] A microsatellite study suggests an alternative to heterozygosity selection. Because no correlation is found between female extra-pair fertilization frequencies and the overall heterozygosity of their social mates, it is suggested that females may choose only a selective set of heterozygous genes, particularly the MHC locus, which can affect the immunocompetence of offspring.[22]
Sexual selection
Males' differential recognition of local and nonlocal songs has been studied in two populations: one in the northern United States (New Hampshire) and the other in the southern United States (North Carolina).[23] An asymmetry of response has been found between the two populations. The northern black-throated blue warbler responds strongly to local songs but relatively weakly to the song of southern warblers. In contrast, a warbler from the south responds equally to songs from both the north and the south. A potential explanation of this asymmetry is the difference in female preference between the northern and southern black-throated blue warblers. Females from the north are less likely to mate with a "heterospecific" male from the south; therefore it is not necessary for a northern male to respond strongly to the song of a southern challenger. It is possible that a barrier to gene flow from south to north exists while a barrier to the reverse does not. Therefore, female choice of male songs is likely to play a role in gene flow and reproductive isolation, which may eventually lead to diversification.[23]
It has long been believed that a male black-throated blue warbler achieves reproductive maturation well into its first breeding season.
Status and threats
The black-throated blue warbler enjoys a large range and a big population. Its population trend is currently increasing. This species was ranked as
References
- ^ . Retrieved 11 November 2021.
- ^ PMID 20696258.
- S2CID 13691956.
- S2CID 25166212.
- ^ S2CID 44401680.
- ^ ISBN 978-84-96553-68-2.
- ^ "Black-throated Blue Warbler Identification, All About Birds, Cornell Lab of Ornithology". www.allaboutbirds.org. Retrieved 2020-09-30.
- ^ a b c "Black-throated blue warbler". Arkive. Archived from the original on 1 May 2011. Retrieved 27 November 2012.
- S2CID 41212347.
- ^ a b c d Cornell Lab of Ornithology. "Black-throated Blue Warbler (Dendroica caerulescens)". Birds in Forested Landscapes. Cornell University. Retrieved 7 January 2013.
- ^ JSTOR 1369601.
- JSTOR 4088201.
- ^ JSTOR 1940130.
- ^ JSTOR 4089333.
- ^ PMID 18559326. Archived from the original(PDF) on 2015-07-18.
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- ^ .
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- doi:10.1139/z97-238.
- ^ S2CID 85702813.
- S2CID 5243261.
- S2CID 127766802.
External links
- Vocals - USGS
- Species account – USGS Patuxent Bird Identification InfoCenter
- Species account – Cornell Lab of Ornithology
- Stamps[usurped] at bird-stamps.org
- "Black-throated blue warbler media". Internet Bird Collection.
- Black-throated blue warbler photo gallery at VIREO (Drexel University)