The parasite behavior hypothesis and the use of sleeping sites by black howler monkeys (Alouatta caraya) in a discontinuous forest

Abstract

The selection of high trees to sleep is a common pattern in primates (Anderson, 1984). In this study howlers slept in tall trees characterized by a closed crown, possibly related to a reduction in predation. We also found selectivity in the trees used as sleeping sites because these trees were not the most abundant in the forest. Selection of sleeping trees was consistent with a predator avoidance hypothesis: Ficus and Tabeuia were the tallest trees in the forest and possibly provided protection against. We also found evidence in support of a thermoregulation hypothesis: they always slept huddled as a group, a social hypothesis: the large crowns of the selected trees allowed the groups to sleep together all the times, a safety hypothesis: trees selected offered large branches and crowns to accommodate the individuals, and a feeding site hypothesis: Ficus trees constituted the most important species in howlers' diet. Although the selection of sleeping trees was consistent with several alternative hypotheses, it was not consistent with parasite avoidance. Parasite avoidance did not appear to have exerted a strong selective pressure on the use of sleeping trees.