Natural mortality patterns in an endangered Andean cervid population

SMITH-FLUECK, JM; FLUCK, WT

Cincinnati, USA

Conferencia; Third Conference of the Wildlife Society; 1996

The Wildlife Society

A survey was made of a population of endangered huemul (Hippocamelus bisulcus) in Argentina where only a total of 600 individuals are estimated to remain. Seasonal habitat use and the current status of a subpopulation in southern Chubut were evaluated. As mechanisms potentially influencing dynamics of huemul populations are not yet understood, dead huemul were collected and analyzed to establish the significance of nutrition, disease and predation. We found huemul used the study area principally during the winter although some individuals remained all year, not migrating to summer ranges at higher elevations. Bones and skeletons were discovered from 15 individuals along a 20 km transect, within 30 meters of a lake shore. Sixty percent of these individuals showed signs of predation by mountain lion (Felis concolor) and all died within the last 4 years (x=2.0). This sample of the population contained 4 fawns, 2 yearlings, and 9 adults (4 females, 4 males, and 1 unidentified). The fat content of bone marrow was between 88% and 98% (n=3) suggesting a population in good physical condition. Only 1 huemul had apparent health problems with an acute infection in the maxilla, possibly from actinomycosis. These results indicate that the principal cause of death was not disease but predation. Knowledge about mortality patterns in huemul populations will benefit conservation efforts to preserve this highly endangered species.