Ramphocinclus brachyurus 


Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Passeriformes Mimidae

Scientific Name: Ramphocinclus brachyurus
Species Authority: (Vieillot, 1818)
Common Name(s):
English White-breasted Thrasher
Identification information: 23-25 cm. Dark brown-and-white bird with long bill. Dark brown upperparts. White underparts. Red iris. Long bill, decurved near tip. Immature, entirely brown and develops white breast-patch with age. Similar spp. Grey Trembler Cinclocerthia gutturalis is larger, less two-toned, grey above and has white iris. Voice Limited repertoire of short, harsh calls, occasionally a musical tee-rou. Alarm call a harsh tschhhh. Juveniles located on ground by thin tseep calls.

Assessment Information [top]

Red List Category & Criteria: Endangered B1ab(i,ii,iii,v) ver 3.1
Year Published: 2015
Date Assessed: 2015-10-01
Assessor(s): BirdLife International
Reviewer(s): Symes, A.
Contributor(s): Cosgrove, P., Gilardi, J., Temple, H., Villard, P., Morton, M. & Mortensen, J.
Facilitator/Compiler(s): Benstead, P., Isherwood, I., Mahood, S., Pople, R., Sharpe, C J, Temple, H., Wege, D. & Ashpole, J
This species has an extremely small range, which is continuing to decline as coastal dry woodland is cleared to make way for agriculture, housing and especially tourism developments. Consequently it warrants Endangered status. Further information is needed to confirm whether the population is likely to decline by ≥80% in three generations (15 years), if evidence supports such a decline this species would warrant uplisting to Critically Endangered.

Previously published Red List assessments:
2012 Endangered (EN)
2008 Endangered (EN)
2006 Endangered (EN)
2005 Endangered (EN)
2004 Endangered (EN)
2000 Endangered (EN)
1996 Endangered (EN)
1994 Endangered (EN)
1988 Threatened (T)

Geographic Range [top]

Range Description: This species occurs as two subspecies which differ in plumage and call notes. The nominate race is restricted to the Caravelle Peninsula on Martinique (to France) (Bulens et al. 1994, P. Feldman and P. Villard in litt. 1998, H. J. Temple in litt. 2003, Temple 2005), an area of c. 5 km2. Race sanctaeluciae occurs on the north-east coast of St Lucia between the Marquis River Valley and Frigate Island Refuge (Keith 1997, J. D. Gilardi in litt. 1999). 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 declining (J. D. Gilardi in litt. 1999, H. J. Temple in litt. 2003). 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. Surveys in 2003 and 2004 indicated a global population of 1,300-2,600 breeding adults, 1,100-2,400 on St Lucia and c.200 on Martinique (Temple 2005). In 2006 and 2007, the St Lucia population still numbered about 1,200 individuals (Young et al. 2010). By 2011, the population on Saint Lucia appeared to be fewer than 900 birds, with under 800 in the southern population (M. Morton in litt. 2012). In 2013 the population in Mandelé on the east of the island was estimated at 1,604 individuals (1,202-2,143) (Felix et al. 2014).

Countries occurrence:
Martinique; Saint Lucia
Continuing decline in area of occupancy (AOO): Yes
Extreme fluctuations in area of occupancy (AOO): No
Estimated extent of occurrence (EOO) - km2: 24
Continuing decline in extent of occurrence (EOO): Yes
Extreme fluctuations in extent of occurrence (EOO): No
Number of Locations: 3
Continuing decline in number of locations: Unknown
Extreme fluctuations in the number of locations: No
Upper elevation limit (metres): 200
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: The population is estimated to number at least 1,300 mature individuals, equivalent to over 1,900 individuals in total.

Trend Justification:  The population trend was previously based on Temple (2005), but the rate of decline increased owing to construction of a hotel that destroyed habitat containing 25% of population. Moderately rapid to rapid declines are therefore estimated. The largest subpopulation (on St Lucia) may be undergoing an even more rapid decline (M. Morton in litt. 2012), having decreased by 56% from 1,766 individuals in 2006 to 760 in 2011 (Morton 2012). If the observed decline in this subpopulation is projected into the future (up to 2024) it suggests the population could decline by 80% in less than ten years (Felix et al. 2014).
Current Population Trend: Decreasing
Additional data:
Number of mature individuals: 1300 Continuing decline of mature individuals: Yes
Extreme fluctuations: No Population severely fragmented: No
No. of subpopulations: 2-100 Continuing decline in subpopulations: Unknown
Extreme fluctuations in subpopulations: No All individuals in one subpopulation: No

Habitat and Ecology [top]

Habitat and Ecology: On both islands, it inhabits dry and semi-dry woodland and scrub with abundant leaf-litter, often in areas with a clear understorey but sometimes in dense thickets. In the northern part of its range on St Lucia (Petite Anse-Dennery Knob) it tends to occur along ravines and river-valleys, but in the rest of its range on St Lucia and Martinique it also occurs on dry hillsides well away from streams. It tolerates a degree of habitat degradation and is often found in secondary woodland and scrub, but although it is occasionally seen in clearings and smallholders' crop-fields, it does not breed in these man-made habitats (Temple 2005). It typically forages on the ground for invertebrates, small frogs and lizards, also taking berries (Keith 1997, Raffaele et al. 1998). Breeding apparently coincides with the onset of the rainy season, and the bulky open-cup nest is placed 0.5-3 m from the ground, usually in the fork of a thin sapling (Keith 1997, J. D. Gilardi in litt. 1999, H. J. Temple in litt. 2003). Eggs (usually two) are laid from May until August, and thrashers may rear more than one successful brood in a season (Keith 1997, J. D. Gilardi in litt. 1999,  H. J. Temple in litt. 2003).

The species sometimes breeds cooperatively - around one-third of nests have helpers, which are apparently retained offspring from previous years, and may be either male or female (Temple et al. 2009, H. J. Temple in litt. 2003). Chicks leave the nest before fledging, and continue to be fed on the ground (J. D. Gilardi in litt. 1999). 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 passerine (J. D. Gilardi in litt. 1999, H. J. Temple in litt. 2003). It is highly sedentary, and may reside permanently on or near breeding territories (J. D. Gilardi in litt. 1999). It occurs at high densities within its restricted range (Temple 2005), suggesting that it may be at carrying capacity, with population increases being unlikely to occur unless more habitat is created (H. J. Temple in litt. 2006).

Systems: Terrestrial
Continuing decline in area, extent and/or quality of habitat: Yes
Generation Length (years): 4.9
Movement patterns: Not a Migrant

Threats [top]

Major Threat(s): 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 area (Temple 2005). Most of this is effectively protected, although some losses to agriculture, charcoal-burning and housing development continue (H. J. Temple in litt. 2006). On St Lucia, on-going 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 of the thrasher's range (J. D. Gilardi in litt. 1999). The Le Paradis resort and golf course is being constructed on St Lucia on a site that is estimated to hold c. 25% of the global population (Temple 2005), and tourism development companies will soon own land equivalent to 35% of the global extent of occurrence (Young et al. 2010). By 2008, 84 ha (12% of the range of St Lucia's southern subpopulation) had been cleared for golf course/hotel construction (M. Morton in litt. 2012). Construction was then halted, but still has planning permission; were it to continue, a projected 248 ha (35% of the southern range) would be lost (M. Morton in litt. 2012). In the northern part of the range on St Lucia, planning permission is being sought for two large estates the development of which would result in approximately 1,000 ha (60%) of the northern range being lost (M. Morton in litt. 2012). Analysis of survival and encounter rates of the species at the Le Paradis tourism development site suggested that birds were emigrating from the area immediately after habitat loss (J. Mortensen in litt. 2013). 

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. Introduced opossums Didelphis marsupialis and domestic cats pose additional threats (Felix et al. 2014). and 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 impact (H. J. Temple in litt. 2003). Additionally, studies have shown the species to be a poor disperser, and it is likely that individuals cannot pass between the two subpopulations on St Lucia, limiting the potential for one population to "rescue" the other from a significant decline (Temple et al. 2006).

Conservation Actions [top]

Conservation Actions: Conservation and Research Actions Underway
The well-protected (albeit small) Caravelle Nature Reserve covers part of the species's range on Martinique. It is legally protected on St Lucia (under Schedule 1 of the 1980 Wildlife Protection Act (revised 1980)), but very little of its St Lucian range falls within a protected area. Four small areas fall under the protection of the St Lucia Forest, Soil and Water Conservation Act which makes it an offence to remove or damage trees within the area or to clear the land (Felix et al. 2014). On both islands, studies have been carried out to assess the population and threats, and on Martinique a plan exists to control introduced predators (Bulens et al. 1994, Temple 2005, P. Feldman and P. Villard in litt. 1998). Banding birds has facilitated detailed ecological and population research (Temple 2005, P. Feldman and P. Villard in litt. 1998, J. D. Gilardi in litt. 1999, H. J. Temple in litt. 2003). A draft action plan for the species was released in 2014 (Felix et al. 2014). By 2020 the 7-year plan aims to have reversed declines so that the population is increasing and at least three sites in St Lucia are being managed for the species.

Conservation and Research Actions Proposed

Monitor both island populations to assess trends. Establish protected areas and effectively protect coastal dry woodland and scrub within the thrasher's range on St Lucia, and prevent further habitat losses on Martinique. Allow adjacent farmland to regenerate into scrub woodland, providing additional habitat and allowing populations to expand. Conduct further research into the impact of predators on Martinique, and implement the predator control plan if deemed necessary. Control predators on St. Lucia (Young et al. 2010). Enact legislation on St Lucia to protect critical wildlife sites. Consult with the hotel developers on St Lucia to protect suitable areas of thrasher habitat in a private reserve (P. Cosgrove in litt. 2007). Safeguard patches of dry forest to the west and north of the Le Paradis tourism development site in Mandelé. Quantify the impact of the Le Paradis development. Preserve mature dry and riparian forest within the tourism development site in Mandelé (Young et al. 2010). Research the taxonomic status of the two subspecies.

Citation: BirdLife International. 2015. Ramphocinclus brachyurus. The IUCN Red List of Threatened Species 2015: e.T22711137A83724384. . Downloaded on 25 November 2015.
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