Justification of Red List Category
Human-induced deforestation, introduced predators and severe habitat loss from volcanic eruptions on Montserrat in 1995-1997 produced rapid population declines, qualifying the species as Vulnerable. The population on Montserrat has increased markedly since 1997 and recent monitoring indicates that the species is both common and stable, but the population status on other islands may be more precarious and is poorly known. If improved knowledge confirms that the species is not declining on other islands, it may warrant downlisting.
Young (2008) estimated a population of 3,100 individuals on Montserrat, and Eraud et al. (2012) estimated 46,000 - 49,000 breeding pairs on Guadeloupe alone. However, both estimates were based on distance sampling which can be highly inaccurate in dense tropical forests given that most Forest Thrush detections are aural. On Montserrat there were 1174 individuals (95% credible interval 624-2178) at the 88 point count stations monitored in the Centre Hills in 2016. These point count stations cover only 20-40% of the available forest habitat (Oppel et al. 2014), hence the population on Montserrat could be between 1,500 - 10,000 individuals.
There are no new data on population trends; however, the species is suspected to be declining, although following the cessation of volcanic activity on Montserrat, not as fast as previously.
Turdus lherminieri is endemic to the Lesser Antilles, where it is uncommon on Montserrat (to U.K.), Dominica and Guadeloupe (to France), and rare on St Lucia. It appears to have declined significantly throughout its range in recent years (Raffaele et al. 1998). The range on Montserrat was reduced by two-thirds in 1995-1997 by the effects of volcanic eruptions (G. Hilton in litt. 2000). However, in December 1999, the population was estimated at 3,100 birds (Arendt et al. 1999), representing an increase of c.50% since December 1997, with further increases up until 2006 (Parashuram 2013). The reasons for these dramatic increases are not known, but the Forest Thrush is the third most abundant bird species in rainforests of Montserrat and improved monitoring between 2011 and 2016 indicated a stable population. On St Lucia, it is now very rare with just one recent record (at Des Chassin in 2007), but was considered numerous in the late 19th century, indicating a serious decline (Keith 1997, L. John in litt. 2016).On Guadeloupe, the species is considered abundant on Basse-Terre, which also holds the largest population, while it occurs at lower densities on Grande-Terre (Eraud et al. 2012, Arnoux 2012). On Dominica it also occurs at low densities, and has been observed in suitable habitat in the northern, western, central, south-eastern and southern regions (J. Arlington in litt. 2007).
It mostly inhabits the undergrowth and edge of mid-altitude and high-altitude primary and secondary moist forest, but can be exceedingly shy where hunted (Bond 1979, Keith 1997, Raffaele et al. 1998). However on Montserrat, although it occurs at all altitudes, the species is most common in mesic mid-elevation forest under closed canopies (Parashuram et al. 2015). Pairs feed on insects and berries from ground-level to the forest canopy (Raffaele et al. 1998). On St Lucia, it previously gathered in large numbers in autumn to feed on berries (Keith 1997). Breeding has been recorded between March and August. The nest is made of dry leaves, twigs and moss, placed 3-10 m above the ground, in forks of large trees or on epiphytes. A clutch typically contains 2-3 blue-green eggs. The incubation period is approximately two weeks and a brood patch is present in both sexes. Chicks stay in the nest for 16-17 days. It is common for this species to nest twice in a year, where it does not build a new nest, but instead rearranges the one used for the first brood (Benito-Espinal and Hautcastel 2003).
Habitat loss has occurred throughout the species's range, but has been particularly acute on Montserrat. Volcanic activity was much reduced during 1998-1999 (G. Hilton in litt. 2000), but a further major volcanic eruption in 2001 caused heavy ash falls across large areas of the remaining habitat. Threats on other islands include brood-parasitism by Shiny Cowbird Molothrus bonariensis; competition with Bare-eyed Thrush Turdus nudigenis, which are increasing on Guadeloupe (A. Levesque and B. Ibene in litt. 2007), and predation by mongooses and other introduced mammals (Raffaele et al. 1998). It is still legally hunted on Guadeloupe (P. Feldmann and P. Villard in litt. 1998), and illegal hunting for food continues on other islands (Raffaele et al. 1998).
Conservation Actions Underway
It occurs in Morne Diablotin and Morne Trois national parks, as well as the Northern and Central forest reserves on Dominica (J. Arlington in litt. 2007), Guadeloupe National Park on Guadeloupe and various forest reserves including Edmond on St Lucia.On Montserrat, remaining habitat in the Centre Hills area is protected and unlikely to suffer any further anthropogenic habitat destruction (Oppel et al. 2015). The species is monitored annually in the Centre Hills, and a stable population has been recorded since improved monitoring started in 2011 (Parashuram 2013, Bambini et al. in prep).
25-27 cm. Medium-sized thrush. All dark brown upperparts. Brownish below with white spots on breast, flanks and upper belly, and white lower belly. Yellow legs, bill and bare skin around eye. Similar spp. On St Lucia, distinguished from Bare-eyed Robin Turdus nudigenis by scaled underparts. Pearly-eyed Thrasher Margarops fuscatus is greyer and has white spots in tail. Voice Soft musical song. Hints Best located by song given from concealed perch.
Text account compilers
Isherwood, I., Mahood, S., Pople, R., Sharpe, C J, Wege, D., Khwaja, N. & Stringer, C.
Arlington, J., Feldmann, P., Hilton, G., Ibene, B., John, L., Levesque, A., Villard, P., Arnoux, E., Morton, M., Parashuram, D. & Oppel, S.
BirdLife International (2017) Species factsheet: Turdus lherminieri. Downloaded from http://www.birdlife.org on 24/11/2017. Recommended citation for factsheets for more than one species: BirdLife International (2017) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 24/11/2017.