Blue-gray tanager
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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.
TaxonomyEdit
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 {{#invoke:Lang|lang}} and the Latin name Episcopus avis.<ref name=brisson>Template:Cite book The two stars (**) at the start of the paragraph indicates that Brisson based his description on the examination of a specimen.</ref> Although Brisson coined Latin names, these do not conform to the binomial system and are not recognised by the International Commission on Zoological Nomenclature.<ref name=allen>Template:Cite journal</ref> 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.<ref name=allen/> One of these was the blue-gray tanager. Linnaeus included a terse description, coined the binomial name Tanagra episcopus, and cited Brisson's work.<ref>Template:Cite book</ref> The specific name episcopus is Latin for "bishop".<ref name=hbwkey>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The current genus Thraupis was introduced by the German naturalist Friedrich Boie in 1826.<ref>Template:Cite journal</ref>
There are 14 recognized subspecies,<ref name=ioc>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> 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.
DescriptionEdit
The blue-gray tanager is Template:Convert long and weighs Template:Convert. 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 habitatEdit
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.<ref name=LPZBlueGrayTanager/><ref>Template:Cite journal</ref> 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.<ref name=LPZBlueGrayTanager/> 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.<ref name="Basto et al"/><ref name="Londono et al"/>
Agricultural ecologyEdit
T. episcopus prospers in some areas cleared by humans<ref name="Borges-2007" /> for grazing, but is not as attracted to buildings or high human or livestock activity.<ref name="Silva-et-al-1996" /><ref name="Hughes-et-al-2002" /> They continue to live in forests<ref name="Borges-2007" /> but eagerly move temporarily into abandoned pasture land for wild fruits<ref name="Silva-et-al-1996" /><ref name="Hughes-et-al-2002" /> and have been variously found to never forage<ref name="Silva-et-al-1996" /> or merely to forage less often<ref name="Hughes-et-al-2002" /> in pasture that has livestock in it. T. episcopus is more common in secondary forest resulting from slash-and-burn<ref name="Morlan">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> followed by abandonment than in primary forest.<ref name="Borges-2007" />
T. episcopus is commonly infected with Blastocystis parasites, specifically Subtype 6 (ST6) which was exclusive to birds in that area.<ref name="Ramirez-et-al-2014" /> ST6 was never found in cows in the area, but it was unassessed whether T. episcopus shares ST6 with nearby domesticated bird flocks.<ref name="Ramirez-et-al-2014" />
StatusEdit
Widespread and common throughout its large range, the blue-gray tanager is evaluated as Least Concern on the IUCN Red List of Threatened Species.<ref name=IUCN/>
SubspeciesEdit
- Blue-grey tanager (Thraupis episcopus quaesita) Las Tangaras.jpg
T. e. quaesita
Colombia - Thraupis episcopus cropped.jpg
T. e. nesophila
Trinidad - Blue-grey tanager (Thraupis episcopus berlepschi).jpg
T. e. berlepschi
Tobago