Abstract # 116:

Scheduled for Saturday, June 19, 2010 10:15 AM-10:25 AM: Session 19 (Mezzanine Ballroom A/B/C/D) Oral Presentation


FOOD CHARACTERISTICS, BUT NOT GROUP SIZE, AFFECT DAILY TRAVEL DISTANCES IN GREY-CHEEKED MANGABEYS (LOPHOCEBUS ALBIGENA) AND REDTAIL MONKEYS (CERCOPITHECUS ASCANIUS) AT KIBALE NATIONAL PARK, UGANDA

M. Brown1,2
1Columbia University, Department of Ecology, Evolution, and Environmental Biology, 1200 Amsterdam Ave, New York, NY 10027, USA, 2The New York Consortium in Evolutionary Primatology
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The ecological constraints hypothesis posits that, all else being equal, large groups must travel farther than small groups to find sufficient food resources. However, other factors may also affect travel distance, such as spatial characteristics of dietary items. This study examines the factors affecting travel distance for two frugivorous primate species. My team observed six grey-cheeked mangabey groups and four redtail monkey groups over 15 months at the Ngogo research station in Kibale National Park, Uganda. Daily travel distances for days with at least 10 observation hours (mangabeys=441 days; redtails=150 days) are included in the analyses. I used a mixed-effects model with group and observation cycle as random effects and observation length, group size, abundance of plant foods, and the density and patchiness of the most common food item per group per observation cycle as fixed effects. The model for each species was significant [mangabeys: Wald X2(8)=34.97, P<0.001; redtails: Wald X2(8)=29.54, P<0.001]: food characteristics, but not group size, affected travel distance in both species. Mangabey travel distance decreased with plant food abundance and increased with the density of the most important food item in each observation cycle; redtail travel distance increased with overall food abundance and decreased with dietary patchiness and density. These results contradict the ecological constraints hypothesis and raise the question of why species with similar diets exhibit different responses to food characteristics.