The Blue-grey Tanager [Thraupis episcopus]

Jan 07, 2018 Features / Columnists, Interesting Creatures in Guyana

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The blue-grey 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]. On Trinidad and Tobago, this bird is called blue jean.
The blue-grey tanager is 16–18 cm (6.3–7.1 in) long and weighs 30–40 g (1.1–1.4 oz). Adults have a light bluish head and underparts, with darker blue upperparts and a shoulder patch coloured a different hue 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.
There are 13–15 commonly recognized subspecies, differing according to the exact hue of blue of the shoulder patch versus the rest of the plumage; they may be greyish, 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.
The breeding habitat is open woodland, cultivated areas and gardens. The blue-grey tanager lives mainly on fruit, but will also take some nectar and insects. 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 grey-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.

Widespread and common throughout its large range, the blue-grey tanager is evaluated as Least Concern on the IUCN Red List of Threatened Species.
The tanagers comprise the bird family Thraupidae, in the order Passeriformes. The family has an American distribution. The Thraupidae are the second-largest family of birds and represent about four percent of all avian species and 12 percent of the Neotropical birds.
Tanagers are small to medium-sized birds. The shortest-bodied species, the white-eared conebill, is nine cm (four in) long and weighs six g (0.2 oz), barely smaller than the short-billed honeycreeper. The longest, the magpie tanager is 28 cm (11 in) and weighs 76 g (2.7 oz). The heaviest is the white-capped tanager which weighs 114 g (4.02 oz) and measures about 24 cm (9.4 in). Both sexes are usually the same size and weight.
Tanagers are often brightly coloured, but some species are black and white. Birds in their first year are often duller or a different colour altogether. Males are typically more brightly coloured than females. Most tanagers have short, rounded wings. The shape of the bill seems to be linked to the species’ foraging habits.
Traditionally, about 240 species of tanagers have been described, but the taxonomic treatment of this family’s members is currently in a state of flux. As more of these birds are studied using modern molecular techniques, some genera are expected to be relocated elsewhere.
Already, species in the genera Euphonia and Chlorophonia, which were once considered part of the tanager family, are now treated as members of Fringillidae, in their own subfamily (Euphoniinae). Likewise, the genera Piranga (which includes the scarlet tanager, summer tanager, and western tanager), Chlorothraupis, and Habia appear to be members of the cardinal family, and have been reassigned to that family by the American Ornithologists’ Union.
Most tanagers live in pairs or in small groups of three to five individuals. These groups may consist simply of parents and their offspring. Birds may also be seen in single-species or mixed flocks. Many tanagers are thought to have dull songs, though some are elaborate.
Tanagers are omnivorous, and their diets vary from genus to genus. They have been seen eating fruits, seeds, nectar, flower parts, and insects. Many pick insects off branches. Other species look for insects on the undersides of leaves. Yet others wait on branches until they see a flying insect and catch it in the air. Many of these particular species inhabit the same areas, but these specializations alleviate competition.
Most tanagers build cup nests on branches in trees. Some nests are almost globular. Entrances are usually built on the side of the nest. The nests can be shallow or deep. The species of the tree in which they choose to build their nests and the nests’ positions vary among genera. Most species nest in an area hidden by very dense vegetation. No information is yet known regarding the nests of some species.
The clutch size is three to five eggs. The female incubates the eggs and builds the nest, but the male may feed the female while she incubates. Both sexes feed the young. Five species have helpers assist in feeding the young. These helpers are thought to be the previous year’s nestlings. [Source: Wikipedia]

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