White-breasted thrasher | |
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Scientific classification | |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Aves |
Order: | Passeriformes |
Family: | Mimidae |
Genus: |
Ramphocinclus Lafresnaye, 1843 |
Species: | R. brachyurus |
Binomial name | |
Ramphocinclus brachyurus (Vieillot, 1818) |
The white-breasted thrasher (Ramphocinclus brachyurus), also known as Goj blan in Creole, is a species of bird in the Mimidae family. Semper and Sclater (1872) describe the white-breasted thrasher as an "inquisitive and noisy bird" that would often "keep up a constant warning chatter, and throw itself about in all sorts of contortions" when being disturbed. It is endemic to Martinique and Saint Lucia, two islands of the Lesser Antilles. This resident species is easy to find within their range; however, it is classified as endangered by the IUCN Red List of Threatened Species mainly due to its restricted habitat.
The white-breasted thrasher is in average 23 to 25 cm long, and weight from 48 to 60 g depending on sex and subspecies. An adult bird has a dark brown plumage with a white throat, breast, and belly. Its dark beak is long and slightly decurved towards the tip. Several dark bristles are located around the lores, between the red eyes and nostrils of the bird. This medium-sized passerine has long and strong black legs and can live up to 7–8 years. Males and females are sexually monomorphic, thus identical in size and coloration. This bird is difficulty sexed by hand or sight due to sexual monomorphism. Males and females have the same plumage and only breeding females can be identified during breading season by their brood patch.
The plumage of an immature white-breasted thrasher is uniformly brown, with a brown throat and a greyish belly. The white patch on its breast will develop with age, around a month later. When the bird is in its first year, it can be differentiated to an adult bird by the rusty brown colour of its upper-parts, and its brownish eye color.
The white-breasted thrasher belongs to a monophyletic group and is the only member of genus Ramphocinclus.
There are two known subspecies of white-breasted thrasher:
Until now, the two subspecies are each restricted to their own habitat location, but they can also be differentiated by their size and coloration. Indeed, R. b. sanctaeluciae is larger, darker, and show a greater sexual dimorphism than R. b. brachyurus.
Because the white-breasted thrasher is endemic to two islands of the Lesser Antilles, its range is dangerously small for species survival.
Until now, there is no evidence of white-breasted thrasher movement between the two islands.
The white-breasted thrasher prefers deciduous tropical dry forests and shrub lands, although the northern population of R. b. sanctaeluciae lives along ravines and river-valleys.