Diet and activity patterns of Arsi geladas in low-elevation disturbed habitat south of the Rift Valley at Indetu, Ethiopia.

Abstract

Understanding the basic natural history of threatened primate taxa is crucial to developing and implementing successful conservation strategies for them. Data on feeding ecology and activity patterns are particularly important for identifying the strategies through which primates invest time and foraging effort towards survival and reproduction at a given locale. Here, we report the results of the first study of the diet and activity budget of Arsi geladas, a population of <1000 individuals endemic to a heavily disturbed region of the southern Ethiopian Highlands and believed to represent a new taxon of geladas. We conducted our research on a band of 34 individuals belonging to five, one-male units at Indetu, eastern Arsi, Ethiopia, from August 2010 to May 2011 (excluding March 2011). Feeding accounted for 41.7% of total scans, followed by moving (20.3%), resting (19.0%), and social behavior (19.0%). Feeding and moving increased and resting and socializing decreased during the dry season when food availability was probably lower than during the wet season. Geladas ate mostly graminoid leaves (51.7% of feeding scans) though they also consumed graminoid rhizomes (24.4%), forb tubers (7.1%), forb leaves (7.1%), cactus, shrub, and tree fruits (3.6%), graminoid corms (1.7%), forb roots (1.6%), and unidentified items (3.0%). Underground foods (corms, rhizomes, roots, and tubers) accounted for 22-47% (mean=35%) of the monthly (n=9) diet and were eaten slightly more during the wet season than during the dry season. Contributions of human crops to the gelada diet could not be quantified without creating conflict between farmers and researchers, though we did note that geladas visited farms on 5-10% of study days. Threats from farmers, children, and dogs limited the geladas' access to crops once they entered the farms. Further research involving questionnaire surveys of farmers, direct observation of crop damage by geladas, and DNA metabarcoding of gelada feces are crucial to the development of strategies to mitigate human-gelada conflict in the densely populated Arsi Zone of Ethiopia.