This discussion was first published on Dec 1 2010 as part of the 2011 Red List update.
Initial deadline for comments: 31 January 2012.
Alagoas Antwren Myrmotherula snowi is currently listed as Critically Endangered under criterion B1a+b(i,ii,iii,v) on the basis that it was thought to occupy an Extent of Occurrence (EOO) of less than 100 km2, in which its habitat is severely fragmented and continuing declines are observed, inferred and/or projected in the EOO, Area of Occupancy (AOO), area, extent and/or quality of habitat and number of mature individuals owing to ongoing habitat loss, fragmentation and degradation.
New records, including that of one adult male documented at Mata do Benedito by Roda et al. (2009), have extended the species’s known range. According to the updated range map for this species’s, its EOO is estimated at 150 km2. This suggests that the species no longer qualifies as Critically Endangered under the B1 criterion, and should be downlisted to Endangered under criteria A2c; A3c; A4c; B1a+b(i,ii,iii,v); C2a(i); D1. The species qualifies as Endangered under these criteria because it occupies an EOO of less than 5,000 km2, in which declines are observed, inferred and/or projected in the EOO, AOO, area, extent and/or quality of habitat and number of mature individuals; the suspected rate of population decline is 50-79% over 10 years, and the population is estimated to number 50-249 mature individuals.
Updated BirdLife range map for Alagoas Antwren
The species’s estimated population size at fewer than 250 mature individuals potentially makes it eligible for listing as Critically Endangered under the C criterion; however, to qualify under criterion C1 the species must be shown to be declining at a rate of at least 25% over three years or one generation (which is estimated at five years). Qualification as Critically Endangered under criterion C2 does not require an estimate of the rate of decline, but it must be shown that all sub-populations number no more than 50 birds or that at least 90% of mature individuals are found in one sub-population.
The species could qualify as Critically Endangered under the A criterion if a population decline in the past, future or both, equivalent to at least 80% over 15 years (three generations) is observed, estimated, inferred or projected.
Comments are invited on the proposed downlisting to Endangered, and further information is requested on the species’s sub-population structure, rate of decline and the severity of threats.
Roda, S. A., Pereira, G. A. and Dantas, S. de M. (2009) Alagoas Antwren Myrmotherula snowi: a new locality and remarks on its conservation. Cotinga 31: 144-146