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Tradeoff Between Travel Speed and Olfactory Food Detection in Ring-Tailed Coatis (Nasua nasua)


Ben T. Hirsch, Smithsonian Institute for Tropical Research, Barro Colorado Island, Unit 9100 Box 0948, DPO AA 34002, Panama.


The distance at which an animal can detect food has important ramifications for foraging behavior. Although some studies have investigated the factors which affect visual food detection, very little is known about what influences olfactory food detection abilities in wild animals. The food discovery behavior of ring-tailed coatis (Nasua nasua) was studied using experimental fruit plots. Coatis primarily used olfaction to detect these new food sources, and visual food discovery appeared plausible in only five of 148 trials. Coatis detected the fruit from longer distances when traveling compared with when foraging for invertebrates in the leaf litter. Travel speed had a negative effect on discovery distance. Coatis traveling slowly detected the fruit plots from further away, which demonstrated a tradeoff between speed and food detection. If this tradeoff is biologically important, slower groups should have visited more fruit trees per day, so data taken during full-day coati group follows were analyzed to determine whether this pattern occurred. Slower moving groups visited more fruit trees than faster groups once confounding factors such as daily travel distance, group identity, group spread, and year were controlled for. These results are consistent with the hypothesis that coatis exhibit a speed-accuracy tradeoff for olfactory food detection. This tradeoff appears to be an important factor influencing the movement ecology of animal groups.