The white-breasted thrasher (''Ramphocinclus brachyurus''), also known as goj blan in Creole, is a species of

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...

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 Martinique ( , ; gcf, label=Martinican Creole, Matinik or ; Kalinago: or ) is an island and an overseas department/region and single territorial collectivity of France. An integral part of the French Republic, Martinique is located in th ...

and

Saint Lucia Saint Lucia ( acf, Sent Lisi, french: Sainte-Lucie) is an island country of the West Indies in the eastern Caribbean. The island was previously called Iouanalao and later Hewanorra, names given by the native Arawaks and Caribs, two Amerindian ...

, found only on these two islands of the Lesser Antilles. This resident species is easy to find within its range; however, it is classified as endangered by the

IUCN Red List of Threatened Species The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biologi ...

mainly due to its restricted habitat.BirdLife International. 2012. ''Ramphocinclus'' brachyurus. TheIUCN RedList of Threatened Species. International Union for Conservation of Nature. Retrieved 29 September 2015.

Description

The white-breasted thrasher is in average 23 to 25 cm long, and weight from 48 to 60 g depending on sex and subspecies.Benstead P, Isherwood I, Mahood S, Pople R, Sharpe C J, Temple H, Wege D. 2015. Species factsheet: ''Ramphocinclus brachyurus''. BirdLife International; ited 2015 Sept. 29 Available from
http://www.birdlife.org
/ref> 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 A passerine () is any bird of the order Passeriformes (; from Latin 'sparrow' and '-shaped'), which includes more than half of all bird species. Sometimes known as perching birds, passerines are distinguished from other orders of birds by t ...

has long and strong black legs and can live up to 7–8 years.Gros-Désormeaux JR, Lesales T, Tayalay AG. 2012. Ethologie du moqueur gorge blanche ''Ramphocinclus brachyurus''. Technical report. CIHENCE. Available from: http://www.pnr-martinique.com/wp-content/uploads/2012/11/rapport-ethologie_CIHENCE_11102012.pdf 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.Mortensen J, Freeman K, Morton M. 2014. White-breasted Thrasher (''Ramphocinclus brachyurus''), Neotropical Birds Online. Ithaca: The Cornell Lab of Ornithology Neotropical Birds; ited 2015 Sept. 29 Available from: http://neotropical.birds.cornell.edu/portal/species/overview?p_p_spp=559116 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.

Taxonomy

The white-breasted thrasher belongs to a

monophyletic group A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

and is the only member of genus ''Ramphocinclus'.'' There are two known subspecies of white-breasted thrasher: * ''Ramphocinclus brachyurus brachyurus,'' * ''Ramphocinclus brachyurus sanctaeluciae'' 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''.

Habitat and Distribution

Distribution

Because the white-breasted thrasher is endemic to two islands of the Lesser Antilles, its range is dangerously small for species survival. * The nominal subspecies, ''R. b. brachyurus'', is only found in

, where its habitat is restricted to a 5 km^2, now protected, area called the Caravelle Peninsula. * Whereas ''R. b. sanctaeluciae'' inhabits

, which is south of Martinique. Two different populations of this subspecies are distinguished by habitat location on the island: a northern population located in Iyanola municipality and a southern one in Mandelé municipality. There is no evidence of white-breasted thrasher movement between the two islands.

Habitat

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.

Behaviour

Diet

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.Gros-Désormeaux JR, Lesales T, Tayalay AG. 2014. Behavioural Observations on the White-Breasted Thrasher (''Ramphocinclus brachyurus brachyurus''): conservation implications. ActaEthol. 18(2):197-208.

Predators

Because white-breasted thrashers are ground eating birds, they are mostly vulnerable to small mammals attacks, but they are also often victim of egg predation. The predator list differ for each subspecies, as the two islands don't have the same fauna and introduced species. ''R.b.sanctaeluciae'' predators are the boa constrictor ('' Constrictor orophias''), the common opossum (''

Didelphis marsupialis The common opossum (''Didelphis marsupialis''), also called the southern or black-eared opossum or gambá, and sometimes called a possum, is a marsupial species living from the northeast of Mexico to Bolivia (reaching the coast of the South Paci ...

''), and the broad-wing hawk ('' Buteo platypterus'') whereas ''R.b.brachyrus'' predators are rats (''Rattus rattus''), the introduced small Asian mongooses (''

Herpestes javanicus The Javan mongoose (''Urva javanica'') is a mongoose species native to Southeast Asia. Taxonomy ''Ichneumon javanicus'' was the scientific name proposed by Étienne Geoffroy Saint-Hilaire in 1818. It was later classified in the genus ''Herpestes ...

''), and cats (''Felis silverstris catus'').Temple HJ, Hoffman JI, Amos W. 2006. Dispersal, philopatry and intergroup relatedness: fine-scale genetic structure in the White-breasted Thrasher, ''Ramphocinclus brachyurus''. ''Molecular Ecology'' 15: 3449-3458.

Vocalization

Vocalization repertoire of the white-breasted thrasher is limited which is surprising for a species that belongs to

Mimid __NOTOC__ The mimids are the New World family of passerine birds, Mimidae, that includes thrashers, mockingbirds, tremblers, and the New World catbirds. As their name (Latin for "mimic") suggests, these birds are notable for their vocalization, ...

s. The white-breasted thrashers often vocalize short and harsh calls, and sometimes a musical "tee-rou". Alarm calls are harsh "tschh" on Saint Lucia, and "grok grok" on Martinique. They are used between birds to warn each other when athreat is perceived. Juveniles are located by thin "tseep" calls.

Reproduction

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 Cooperative breeding is a social system characterized by alloparental care: offspring receive care not only from their parents, but also from additional group members, often called helpers. Cooperative breeding encompasses a wide variety of group s ...

. 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.

Conservation Status

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).White-breasted Thrasher nternet 2007. Martinique (FWI): Life Cap Dom; ited 2015 Sept. 29 Available from: http://www.lifecapdom.org

References

External links

Les hot-spots du Moqueur gorge-blanche en Martinique.

White-breasted thrasher sound.
{{Taxonbar, from=Q2225784

white-breasted thrasher 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 woul ...

Birds of Martinique Birds of Saint Lucia Endemic birds of the Caribbean Higher-level bird taxa restricted to the West Indies

Taxa named by Louis Jean Pierre Vieillot Taxonomy articles created by Polbot