Archived 2011-2012 topics: Alagoas Antwren (Myrmotherula snowi): downlist to Endangered?

This discussion was first published on Dec 1 2010 as part of the 2011 Red List update.

Initial deadline for comments: 31 January 2012.

Link to BirdLife species factsheet for Alagoas Antwren

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

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One Response to Archived 2011-2012 topics: Alagoas Antwren (Myrmotherula snowi): downlist to Endangered?

  1. Ciro Albano says:

    As a Ornithologist and a Birdwatching guide specialized in North-east Brazil I’m frequently visiting the region where Alagoas Antwren and all the other Endemics of this region occurs. At least 6 times per year I go to Murici Ecological Station and Jaqueira (aka Frei Caneca) Reserve that harbors the best forest fragment of the Serra do Urubu mountain Range; where SAVE Brasil recently bought a Reserve.
    But the new about this bird are not good; the last documented record in Serra do Urubu mountain range was in Dec 2007 when I tape recorded a female that was in a mixed flock with White-flanked Antwren. After this record; I and many others birders came back to the area but no success to find the Alagoas Antwren.
    At Murici Ecological Station; in all the trips during the last 5 years we find at least one pair in the main trail (3 km). But they are externally rare and most of the record can be of the same pair…
    I’ve being just one time in the other two areas (very small fragments) where the species also occurs; no success to find it in Mata do Estado in two days of search and in Engenho Jussara one pair was seen in the same territory where they were fist found.
    So; based on the field experience I really believe that this species is a Critically Endangered species as it’s one of the rarest birds on the very small forest fragments where they still surviving.

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