A population estimate of blue-eyed black lemurs in Ankarafa Forest, Sahamalaza-Iles Radama National Park, Madagascar.

The critically endangered blue-eyed black lemur (Eulemur flavifrons) has one of the smallest distributions of any lemur, occurring only in the north-western forests of Madagascar. We report the results of a population estimate of this taxon in part of the Ankarafa Forest, Sahamalaza-Iles Radama National Park, a dry deciduous forest. We collected data between September 2007 and February 2008 using a total count method with marked individuals and known groups. In all, 228 individuals comprising 29 groups were counted. Group sizes ranged from 4 to 11 individuals with a mean of 8 ± 1.8. We estimated population density to be 1.0 individual/ha or 97.3 individuals/km(2) for our study area, which is higher than previous estimates reported for Ankarafa and other sites within the Sahamalaza Peninsula. Our mean group size, however, was similar to those determined in previous studies. Both group size and density of the blue-eyed black lemur were higher within the National Park than in previous studies outside the Park.