This discussion was first published as part of the 2012 Red List update, but remains open for comment to enable reassessment in 2014.
Tamaulipas Pygmy-Owl Glaucidium sanchezi occurs in montane forest in a restricted range in the states of Tamaulipas, San Luis Potosí and Hidalgo, in north-eastern Mexico. It is listed as being of Least Concern on the basis that it was not thought to approach any of the thresholds for Vulnerable under the IUCN criteria.
Although this species appears to have a restricted range, it was not believed to approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence [EOO] of less than 20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend was suspected to be stable, and hence the species did not approach the thresholds for Vulnerable under the population trend criterion (at least a 30% decline over ten years or three generations). The population size may be moderately small to large, currently placed in the band 20,000-49,999 individuals, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (fewer than 10,000 mature individuals with a continuing decline estimated to be at least 10% over ten years or three generations, or with a specified population structure).
Remapping of this species’s range has resulted in a new estimated EOO of 19,300 km2. The species is probably threatened by habitat destruction through logging (König and Weick 2008), thus it may be reasonable to regard the Area of Occupancy (AOO) and area, extent and/or quality of habitat as being in decline and suspect an on-going decline in the population. However, the species will only qualify as Vulnerable if it is shown that the remaining habitat is severely fragmented (typically over 50% in fragments too small to support viable populations) or that the species is known from 10 locations or less. According to the IUCN definition of ‘location’, it relates to a geographically or ecologically distinct area in which a single threatening event can rapidly affect all individuals of the species present. The size of the location depends on the area covered by the threatening event and may include part of one or many subpopulations. If not all of the subcriteria are met, the species may still qualify as Near Threatened.
Comments on the potential uplisting of the species and further information are requested, in particular information on the level of habitat fragmentation and number of locations.
König, C. and Weick, F. (2008) Owls of the World. Second Edition. London, UK: Christopher Helm.
The following document was sent by Pronatura on 16 February 2012: Glaucidium sanchezi Pronatura Feb12