Distribution and habitat associations of baboons (Papio hamadryas) in Central Eritrea

At least three diurnal primate taxa are still present in Eritrea, NE Africa : hamadryas baboons (Papio hamadryas hamadryas), olive baboons (Papio h. an ubis) and grivet monkeys (Chlorocebus aethiops aethiops). However, informat ion on status and distribution of primates and their habitats in Eritrea is outdated and incomplete. We conducted a primate survey, focussing on hamad ryas baboons, to obtain data which will be integrated in a national wildlif e management and conservation plan in Eritrea. We obtained information abou t the geographical distribution and abundance of baboons, their altitudinal range habitat quality of their home-ranges, aggregation sizes at sleeping cliff and predator presence. We described habitat quality via the Normalize d Difference Vegetation Index (NDVI), a vegetation classification of Landsa t MSS satellite data. Hamadryas and olive baboons are still present in Erit rea in ample numbers. Their geographical distributions in 1997 and 1998 did not deviate significantly from their historical distributions. An estimate d 15,000 Papio hamadryas hamadryas lived in the 25,000-km(2) area of survey (0.58 baboons/km(2)). Population densities of hamadryas baboons in many pa rts of the survey area are higher than at Kummer's (1968) study site in Eth iopia. Hamadryas baboons live at all altitudes in four of five ecogeographi cal zones of Eritrea. Olive baboons replaced them in the western lowlands B oth baboon taxa tend to select better quality habitats, characterized by a higher normalized difference vegetation index (NDVI) than the average for t he respective ecogeographical zones. Hamadryas baboons show a greater ecolo gical plasticity than olive baboons which are confined to riverbeds with ex tended gallery forest By the end of 1999 a hybrid zone could not be confirm ed.