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Ramphocinclus brachyurus
– Endangered
Taxonomy
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Kingdom:
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ANIMALIA
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Phylum:
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CHORDATA
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Class:
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AVES
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Order:
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PASSERIFORMES
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Family:
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MIMIDAE
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Scientific Name:
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Ramphocinclus brachyurus
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Species Authority:
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(Vieillot, 1818)
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Common Name/s:
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| English | — | WHITE-BREASTED THRASHER |
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Assessment Information
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Red List Category & Criteria:
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EN B1ab(ii,iii) ver 3.1 (2001)
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Year Assessed:
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2006
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Assessor/s:
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BirdLife International
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Evaluator/s:
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Butchart, S. & Temple, H. (BirdLife International Red List Authority)
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Justification:
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This species has an extremely small range, which is continuing to decline as coastal dry woodland is cleared to make way for agriculture and housing and tourism developments. Consequently it warrants Endangered status.
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History:
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| 1988 | - | Threatened (Collar and Andrew 1988) |
| 1994 | - | Endangered (Collar, Crosby and Stattersfield 1994) |
| 2000 | - | Endangered (BirdLife International 2000) |
| 2004 | - | Endangered (BirdLife International 2004) |
| 2005 | - | Endangered (BirdLife International 2005) |
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Geographic Range
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Range Description:
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Ramphocinclus brachyurus occurs as two subspecies. The nominate race is restricted to the Caravelle peninsula on Martinique (to France)1,2,6,7, an area of c.5km², and race sanctaeluciae occurs on the north-east coast of St Lucia between the Marquis river valley and Frigate Island Refuge3,4. Until 1993, the thrasher was thought to be restricted to the northern part of this area (Marquis-Dennery Knob), and population estimates and censuses in 1971, 1987, 1992 and 2003 suggested that the population in this northern area may be declining3,6. In 1993, thrashers were discovered near the Frigate Island Refuge, and recent research suggests that this site holds the bulk (c.75%) of the global population. A comprehensive programme of searches on Martinique found no new subpopulations anywhere else on the island (G. Tayalay verbally 2004). Surveys in 2003 and 2004 indicate a global population of 1,300-2,600 breeding adults, 1,100-2,400 on St Lucia and c.200 on Martinique7.
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Countries:
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Native:
Martinique; Saint Lucia
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Population
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Population Trend:
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Habitat and Ecology
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Habitat and Ecology:
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On Martinique, it occurs in scrubby dry woodland with abundant leaf-litter and a clear understorey. On St Lucia, it inhabits low scrubby woodland in ravine bottoms with dense stands of thin-trunked riparian trees, but has been found breeding on hillsides away from rivers3. It forages on the ground for small invertebrates, berries and occasionally small frogs and lizards4,5. Breeding apparently coincides with the onset of the rainy season, and the bulky open-cup nest is placed 0.5 - 3m from the ground, usually in the fork of a thin sapling3,4,6. Eggs (usually two) are layed from May to August, and thrashers may rear more than one successful brood in a season3,4,6. Sometimes breeds cooperatively - around one-third of nests have helpers, which are apparently retained offspring from previous years, and may be either male or female6. Chicks leave the nest before fledging, and continue to be fed on the ground3. On St Lucia, nesting success was 44% in 1997, 55% in 2001, 74% in 2002 and 44% in 2003, suggesting normal levels of nest-predation for a tropical passerine3,6. Birds may breed less than annually3. It is highly sedentary, and may reside permanently on or near breeding territories3.
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System:
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Terrestrial
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Threats
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Threats:
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The main threat to this species is habitat loss, perhaps compounded by the impact of predation by introduced mammals. On Martinique, habitat loss during the colonial era means that the species now has a tiny population restricted to a very small area7. Most of this is effectively protected, although some losses to agriculture, charcoal-burning and housing development continue8. On St Lucia ongoing habitat degradation and loss is caused by agriculture, charcoal-burning and wood-cutting, and there are potentially devastating plans to build a highway through the centre the thrasher's range3. A resort and golf course are being constructed on St Lucia on a site that is estimated to hold c.25% of the global population7. Small Indian mongoose Herpestes auropunctatus and rats Rattus spp. have been present on both islands since before 1900, implying that the thrasher is able to coexist with these predators, but they may place an unwelcome additional burden on an already small population. Nest-monitoring on St Lucia suggests that levels of nest predation are not excessive, but the situation could be different on Martinique, where rats and mongoose may be more abundant: further research is required. Because the thrasher is confined to narrow areas along the Windward coast, a major hurricane could have a severe impact6.
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Conservation Actions
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Conservation Actions:
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Conservation measures underway:
The well-protected Caravelle Nature Reserve has been established on Martinique for this species, and the species is legally protected on St Lucia. On Martinique, there has been a three-year study to assess the population and threats, and a plan exists to control introduced predators1,2. On St Lucia, a similar three-year study is ongoing6. Banding birds has facilitated detailed ecological and population studies2,3,6.
Conservation measures proposed:
Monitor the population to assess trends. Assess breeding frequency, the proportion of birds breeding in any year and survivorship in different age groups3. Implement the predator control plan on Martinique.
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