Student Prize Award Abstract
2000 Oral Paper Award

FACTORS AFFECTING VARIATION IN DAILY FOOD IN-TAKE BY WILD GOLDEN LION TAMARINS (LEONTOPITHECUS ROSALIA)

K. Miller and J. Dietz Department of Biology, University of Maryland, College Park, MD 20742

Foraging success affects an animal's chances of surviving and reproducing. Therefore, it is valuable to understand variation in feeding and diet selection. Altmann (1998) argued that average daily mass intakes, as opposed to time spent feeding, more accurately estimate the amount of foods consumed. Several factors, including risk of predation while feeding, seasonality and abundance of food, maximum levels of toxins tolerated by animals and nutrient requirements of animals, may explain variation in the amounts of foods consumed. However, Altmann argued that these factors are complementary and cannot be used individually to explain variation in food intakes. Therefore, we calculated daily food intakes of wild golden lion tamarins while concurrently quantifying several factors that may explain variation in food intake. These factors included predation risk, food abundance and seasonality, and energy content of the foods. We collected 668 hours of focal data from January 1998-May 1999 on 56 individuals in 8 groups of tamarins in Poco das Antas Reserve, Brazil. We used transect counts to estimate numbers of fruit trees in territories of the study groups. We estimated the quantity of fruits in trees used by tamarins and used bomb calorimetry to determine the energy contents of fruits and prey. Preliminary analyses suggest that energy content and seasonality and abundance of food have greater influences on variation in food intake than the risk of predation does.