Departamento de Biodiversidade e Ecologia, Pontifícia Universidade Católica do Rio Grande do Sul, Brazil
Friday 5:15-5:30, Ballroom C
The ability to discriminate among varying amounts of food resources plays an important role in the process of patch choice. By increasing foraging efficiency this ability may also reduce feeding competition among social animals. We tested whether 11 captive marmoset (Callithrix jacchus, C. penicillata, and C. penicillata vs. C. kuhlii hybrids; 2-4 individuals) groups would respond to differences in food availability in making foraging decisions. Five white plexiglass boxes (11 x 25 x 20 cm) were placed in each group’s cage. Each box had a cup in its back where food rewards (1 cm banana slices) were hidden. During 20 consecutive days the same box contained three available slices (richest box), another contained a single available slice and two unavailable slices within a wire-mesh cage (poorest box), whereas the remaining three boxes contained three unavailable slices (non-reward boxes). Unavailable slices aimed at equalizing odor cues. Each study group was tested once a day early in the morning just after its release from the nest box. Marmosets from seven groups inspected the richest box as their first choice above a 20% chance level (1 out of 5 boxes) and two groups selected it above a 50% chance level (1 out of 2 reward boxes). Also, there is evidence that marmosets were learning to differentiate the boxes based on food availability as the number of groups going directly to the richest box in each session increased along the experiment. The influence of hunger, stress, and competition on these results is discussed.
We thank the Brazilian National Research Council (CNPq) for financial support.