Forrageamento de alouatta guariba clamitans cabrera, 1940 (primates, atelidae) em áreas fragmentadas da Mata Atlântica: influência de metabólitos secundários de plantas e da florística e estrutura das comunidades arbóreas

Garcia, Vania

Abstract

The foraging and behavioral activity patterns of Alouatta guariba clamitans (brown howlers) were studied in two semideciduous patches of the Atlantic forest. The main goal of this study was to examine how disturbed forest patches may be influencing diet quality and behaviour of this primate species. More specifically, the role of plant secondary metabolites and the (structural and floristic) composition of tree communities was evaluated. In that sense, the null hypothesis is that forest fragmentation results in a less diverse and a less palatable diet (i.e., richer in secondary metabolites). Phytosociological studies were carried out on one thousand tree samples in each fragment with the Fitopac program. A group of brown howlers from each fragment was selected to collect behaviour data systematically. The scan sampling method was used and applied at ten-minute intervals, during summer and winter. Two groups of plant samples (species consumed versus species non-consumed in howlers diet) were collected in order to determine the total amount of a major secondary metabolity class that includes phenols, through the Folin-Denis method, and of condensed tannins, with the Proanthocyanidin method. Both forest patches presented low floristic similarities, and, as expected, a higher tree diversity was observed in the larger patch. Notably, a higher density of species that are typically found in altered environments was observed in the smaller patch, an indicative of a critical disturbance in the area. In both cases, leaves were the main item of the diet, yet in the larger patch, howlers exhibited a richer and a more diverse diet, including fruits, when compared to the more selective diet howlers of other patch. Howlers of the larger fragment also presented a more active behaviour, since they spent less time resting, and showed various feeding and locomotion activities. Plants with higher concentrations of total phenols and condensed tannins were excluded from the diet, whereas plants that contained lesser concentrations of these substances were included. Additionally, the ratios of condensed tannins and total phenols concentrations was significantly higher in the larger fragments, as expected by the “appearance” hypothesis. Although the diet is not less palatable or even more toxic in the smaller fragments, a more selective forraging strategy is consolidated in these areas. Apart from the diversity loss in their diet, fragmentation favors plant dispersion and the establishment of arboreous species that do not represent an adequate item in the brown howlers diet.

• Thesis Type: Dissertation
• Deposit Date: Mar 19, 2024
• Award Date: Feb 5, 2007