Blue-gray Tanager

The blue-gray tanager (''Thraupis episcopus'') is a medium-sized South American songbird of the tanager family, Thraupidae. Its range is from Mexico south to northeast Bolivia and northern Brazil, all of the Amazon Basin, except the very south. It has been introduced to Lima (Peru) and Florida (USA). On Trinidad and Tobago, this bird is called blue jean.

Taxonomy

In 1760 the French zoologist Mathurin Jacques Brisson included a description of the blue-gray tanager in his ''Ornithologie'' based on a specimen collected in Brazil. He used the French name and the Latin name ''Episcopus avis''. The two stars (**) at the start of the paragraph indicates that Brisson based his description on the examination of a specimen. Although Brisson coined Latin names, these do not conform to the binomial system and are not recognised by the International Commission on Zoological Nomenclature. When in 1766 the Swedish naturalist Carl Linnaeus updated his ''Systema Naturae'' for the twelfth edition, he added 240 species that had been previously described by Brisson in his ''Ornithologie''. One of these was the blue-gray tanager. Linnaeus included a terse description, coined the binomial name ''Tanagra episcopus,'' and cited Brisson's work. The specific name ''episcopus'' is Latin for "bishop". The current genus ''Thraupis'' was introduced by the German naturalist Friedrich Boie in 1826.

There are 14 recognized subspecies, differing according to the exact hue of blue of the shoulder patch versus the rest of the plumage; they may be grayish, greenish, or purplish-blue, with a lavender, dark blue, or whitish shoulder patch. For example, ''T. e. berlepschi'' (endemic to Tobago) is a brighter and darker blue on the rump and shoulder; ''T. e. neosophilus'' with a violet shoulder patch occurs in northern Venezuela, Trinidad, eastern Colombia, and the far north of Brazil; ''T. e. mediana'' of the southern Amazon basin has a white wing patch; and ''T. e. cana'' in the northern Amazon has blue shoulders.

Description

The blue-gray tanager is long and weighs . Adults have a light bluish head and underparts, with darker blue upperparts and a shoulder patch colored a different shade of blue. The bill is short and quite thick. Sexes are similar, but the immature is much duller in plumage.

The song is a squeaky twittering, interspersed with ''tseee'' and ''tsuup'' call notes.

Breeding and habitat

The breeding habitat is open woodland, cultivated areas, and gardens. The blue-gray tanager lives mainly on fruit, but will also take some nectar, insects, and other arthropods. This is a common, restless, noisy, and confiding species, usually found in pairs, but sometimes small groups. It thrives around human habitation, and will take some cultivated fruit like papayas (''Carica papaya'').

One to three, usually two, dark-marked whitish to gray-green eggs are laid in a deep cup nest in a high tree fork or building crevice. Incubation by the female is 14 days with another 17 to fledging. The nest is sometimes parasitised by ''Molothrus'' cowbirds.

Two birds studied in the Parque Nacional de La Macarena of Colombia were infected with microfilariae, an undetermined ''Trypanosoma'' species, and another blood parasite that could not be identified. Two other birds, examined near Turbo (also in Colombia), did not have blood parasites.

Agricultural ecology

''T. episcopus'' prospers in some areas cleared by humans for grazing, but is not as attracted to buildings or high human or livestock activity. They continue to live in forests but eagerly move temporarily into abandoned pasture land for wild fruits and have been variously found to never forage or merely to forage less often in pasture that has livestock in it. ''T. episcopus'' is more common in secondary forest resulting from slash-and-burn followed by abandonment than in primary forest.

''T. episcopus'' is commonly infected with ''Blastocystis'' parasites, specifically Subtype 6 (ST6) which was exclusive to birds in that area. ST6 was never found in cows in the area, but it was unassessed whether ''T. episcopus'' shares ST6 with nearby domesticated bird flocks.

Status

Widespread and common throughout its large range, the blue-gray tanager is evaluated as Least Concern on the IUCN Red List of Threatened Species.

Subspecies

File:Blue-grey tanager (Thraupis episcopus quaesita) Las Tangaras.jpg, ''T. e. quaesita''
Colombia
File:Thraupis episcopus cropped.jpg, ''T. e. nesophila''
Trinidad
File:Blue-grey_tanager_(Thraupis_episcopus_berlepschi).jpg, ''T. e. berlepschi''
Tobago

References

Further reading

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External links

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* from Belize, Panama, Suriname at

Photo at stevenrotsch.com
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{{Taxonbar, from=Q883102

blue-gray tanager
Birds of Central America
Birds of Colombia
Birds of Venezuela
Birds of Ecuador
Birds of Trinidad and Tobago
Birds of the Guiana Shield
Birds of the Amazon rainforest
Birds of Peru
blue-gray tanager
blue-gray tanager
Birds of Brazil
Birds of the Caribbean
Taxobox binomials not recognized by IUCN