Initial deadline for comments: 31 January 2012.
BirdLife species factsheet for Dull-mantled Antbird (prior to taxonomic change)
Dull-mantled Antbird Myrmeciza laemosticta and Magdalena Antbird M. palliata have been split following a study into these taxa’s vocalisations and genetic divergence (Chaves et al. 2010), and a further discussion in reaction to the resulting SACC proposal, which has now been approved.
Prior to this taxonomic change, Dull-mantled Antbird was listed as being of Least Concern, on the basis that it was not considered to approach the thresholds for Vulnerable under any of the IUCN criteria, although it was noted that the population was likely to be decreasing.
M. laemosticta (as defined following the taxonomic change) occurs in mature foothill forest along the length of the Caribbean slope of Costa Rica (Garrigues and Dean 2007), and is described as rare and local in Panama, where it occurs on both slopes, from Veraguas eastward, favouring foothill forest, but also ranging into lowland areas (Angehr and Dean 2010).
M. palliata occurs in northern Colombia, being present on the northern slope of the Andes and in the Magdalena Valley, and ranges into north-western Venezuela (del Hoyo et al. 2003). It inhabits humid and wet forests, mostly in the foothills, but also ranges down into lowland and up into lower montane habitats in some areas, although it is more numerous in foothill forest (Hilty and Brown 1986, del Hoyo et al. 2003).
Remapping of both species’ ranges suggests that they do not approach the range size threshold for Vulnerable under criterion B1 (with estimated Extents of Occurrence [EOOs] of 41,700 km2 for M. laemosticta, and 88,400 km2 for M. palliata), and thus may have large populations; however, both species are suspected to be in decline owing to on-going habitat loss.
M. palliata occupies a region that is subject to extensive land-use change. The middle and lower Magdalena valley has been extensively deforested since the 19th century for agriculture, and clearance of its foothills has been near total since the 1950s (Forero 1989). Deforestation in the Caribbean lowlands of Colombia has also been severe (T. Donegan in litt. 2009). In addition to clearance for agriculture, deforestation is being driven by gold mining in the Serranía de San Lucas (T. Donegan in litt. 2009).
Similarly, a decline in the population of M. laemosticta is suspected on the basis of forest clearance. The lowlands and foothills of eastern Panama have been heavily deforested during the last 30 years, and this is continuing at a rapid rate (G. Angehr in litt. 2011). Deforestation is on-going near El Real and is likely to be taking place in the Jaque valley (G. Angehr in litt. 2011). Mining, the completion of the Pan-American Highway and the impact of a rising human population resulting from such projects are potential future threats (Adsett and Wege 1998).
The likely rates of population decline are not known for these species, thus further information is requested on the severity of threats, in particular the rate and extent of habitat loss. If evidence suggests that their rates of population decline approach 30% (typically 20-29%) over three generations, estimated by BirdLife to be 14 years (based on an estimated generation length of c.4.8 years), these species might be eligible for listing as Near Threatened. If evidence points towards a decline of 30% or more over the same time scale they may qualify as Vulnerable. They would qualify as Endangered if the rate of decline were suspected to be 50% or more over three generations.
Adsett, W. J. and Wege, D. C. (1998) Natural history of the little-known Speckled Antshrike Xenornis setifrons. Cotinga 10: 24-29.
Angehr, G. and Dean, R. (2010) The Birds of Panama: A Field Guide. Ithaca, NY: Cornell University Press.
Chaves, J. C., Cuervo, A. M., Miller, M. J. and Cadena, C. D. (2010) Revising species limits in a group of Myrmeciza antbirds reveals a cryptic species within M. laemosticta (Thamnophilidae). Condor 112: 718-730.
del Hoyo, J., Elliott, A. and Christie, D. (2003) Handbook of the Birds of the World, vol 8: Broadbills to Tapaculos. Barcelona, Spain: Lynx Edicions.
Forero, E. (1989) Colombia. Pp. 355-361, in Campbell, D. G. and Hammond, H. D., eds. Floristic inventory of tropical countries. New York: New York Botanical Garden.
Garrigues, R. and Dean, R. (2007) The Birds of Costa Rica: A Field Guide. London, UK: Christopher Helm.
Hilty, S. L. and Brown, W. L. (1986) A guide to the birds of Colombia. Princeton, NJ: Princeton University Press.