Student Prize Award Abstract
2000 Poster Paper Award

CAPTIVE GEOFFROY'S MARMOSETS (CALLITHRIX GEOFFROYI) REACT TO SOARING BIRD MODELS WITH ANTI-PREDATOR BEHAVIORS

Y. M. Searcy and N. G. Caine Department of Psychology, California State University San Marcos, CA 92096, and the Center for Reproduction of Endangered Species, Zoological Society of San Diego, San Diego, CA 92112

While callitrichids may startle to most any object appearing suddenly and flying rapidly overhead, there is some evidence that marmosets and tarmarins react differently to predatory and non-predatory flying birds. The basis of this distinction is usually presumed to be the shape of the bird. We tested the prediction that marmosets would react more strongly to a soaring model of a predatory bird than a non-predatory bird when size, color, speed, sudden appearance, flight path, and exposure time were held constant. Focal animals in two family groups (N=13) of captive, outdoor-living marmosets were observed before, during, and after exposure to flights of hawk and duck models, and to the flight pole alone (control). As predicted, the marmosets startled to all three stimuli. The duck and hawk models were associated with increased visual attention to the origin of the stimuli, increased use of the most protected area of the enclosure, reduced foraging , and increased huddling compared to baseline rates. However, the duck model caused longer freeze times and, overall, more behavioral disruption than the hawk model. These data suggest that any large, suddenly appearing bird might generate a protective set of responses in callitrichids and that the predatory status of a bird, as reflected in the bird's shape, might not be the only information used by monkeys to guide their defensive reactons.