Goj blan
The white-breasted thrasher (Ramphocinclus brachyurus ), also known as goj blan in Creole, is a species of bird in the family Mimidae. 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, found only on these 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.
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TerrestrialTerrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
Oviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
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Not a migrantAnimals that do not make seasonal movements and stay in their native home ranges all year round are called not migrants or residents.
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starts withThe 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.
Because the white-breasted thrasher is endemic to two islands of the Lesser Antilles, its range is dangerously small for species survival.
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.
The semi wooded habitats carefully selected by this habitat specialist must be located within 2 km of the coast, and up to 200 m above sea level. Low canopy shrubs and clear spaces are avoided by both subspecies because of predation, especially during breeding. Soils with an abundant leaf-litter are also favoured for feeding.
The white-breasted thrasher's diet is adaptable and goes from animal proteins to fruits. Feeding habits depend on what's available to the bird according to environmental conditions. White-breasted thrashers are ground eaters. They forage mainly on leaf litter fauna, looking for insects or berries. They also have the ability to regurgitate a whole berry and spit out seeds to save it for a later meal.
The white-breasted thrasher's breeding season starts mid-April and lasts until the end of September. A breeding bird can have up to four successive broods in one breeding season and the average clutch size varies from 1 to 3 eggs. Birds usually live in pair and build voluminous nests in high trees from 1.5 to 5 m above the ground. Before using a nest, a pari of bird usually build several of them. Each individual takes turn in nest building tasks. For instance, each bird sit in the nest, in turns, to adjust the inside part of it. White-breasted thrashers are thus called cooperative breeders.
Because of egg predation, nesting failure is relatively high and white-breasted thrashers came with an anti-predatory strategy that consists of keeping their nests clean of eggshells and fecal sacs to reduce nest detection.
The white-breasted thrasher total population is estimated at 1900 individuals and is ranked as "endangered" according to the IUCN Red List. The rate of decline of the population has largely increased due to habitat loss on both islands. The white-breasted thrasher is able to coexist with some of its predators such as rats and mongooses. However, this predation places an additional burden on the already small thrasher population, especially in Martinique where rats and mongooses are more abundant. That is why organizations charged with environmental protection have started several programs such as: rats extermination and mongoose capture program, and also a program aimed at monitoring the reproduction success of the R. b. brachyurus (in which one of the tasks consists of fixing plastic bottles on nesting trees trunks, preventing predators to reach the nest).
