Ecologia comportamental de Saguinus midas e Saguinus bicolor (Primates: Callitrichidae) em áreas de contato entre distribuições geográficas

Abstract

The pied tamarinSaguinus bicolor (Primates: Callitrichidae) has a small geographic range (75000 km²) restricted to Central Amazonia, in and around the city of Manaus. In recent decades, a continued reduction in its range has been observed, coinciding with an expansion of a second tamarin species, Saguinusmidas which seems to be slowly encroaching the range of the pied tamarin. As result, these species have been considered to be competing, although, little is known about their interaction throughout the contact areas of their ranges. Aggressive displays have been observed during encounters between the two species. Based on these observations, here we tested the hypothesis that S.midas is dominant over S. bicolor and wins in events of contest competition along territory boundaries in areas where the two species co occur. We tested our hypothesis by means of playback experiments since this is the main form of agonistic interaction in Saguinus. In addition, we assessed whether agonistic displays are more likely to occur in certain parts of the forest (canopy, understory, etc) where contest for important resources could potentially be more important. Therefore, we recorded the responses of one species subjected to recorded vocalizations of the other species in different parts of the forest including areas of contact and non-contact between their geographical distributions. Playbacks consisted of the issuance of long calls. During playback experiments, we recorded habitat type as well as the forest stratum used by the animals. Sixteen groups of S. midas and fourteen of S. bicolor had their aggressive vocalizations recorded and accounted for after the issuance of playbacks. The tamarins did not respond differently in areas of contact and non-contact of their geographic distribution. The number of aggressive vocalizations was independent of the type of habitat and tree layer used. Tamarins did not differ in duration of stay in the experimental area during the playback emission. These results suggest that there is no behavioral dominance relationship between species. Finally, we recorded that even if tamarins are very territorial, they were not asymmetrically aggressive when food resources were scarcer. T