Brown howler

Distribution

The brown howler lives in the Atlantic forest in South America. The region spreads through the Brazilian states of Bahia and Espirito Santo through the Rio Grande do SUl and the Misiones in the Argentine

Behavior

The black hawk eagle is a predator of the brown howler monkey. The roars of the brown howler allow the black hawk eagle to determine their location. The brown howler’s response has three parts. First, when one brown howler becomes aware of a black hawk eagle they will alarm the group and then they will immediately become silent. Next they descend in the understory of the trees, and finally they will all disperse in an organized manner. The adults will lead the young away from danger. The young are considered to be the primary target for the black hawk eagle. There is a more conservative response when adult brown howlers are without the young, and the black hawk eagle is present, thus indicating that the black hawk eagles are targeting the young howlers. When the brown howler monkey is threatened by terrestrial animals they will remain in the tree canopy and remain silent for 5–15 minutes.

Reproduction

It is difficult to breed the genus ''Alouatta'' in captivity and therefore the reproduction is relatively unknown. Brown howlers reproduce year round. There seems to be no correlation to birth rates in rainy or dry season or in times of increased fruit or leaves. It is thought that because the brown howler has a folivorous diet, conception is less dependent on maternal conditions. The average interbirth interval for the brown howler is 19.9 months, which is similar to other howler species. It does not seem that the sex of the infant or the number of females in the population has a significant effect on IBI. The death of an infant will shorten the mother's IBI and seems to be one of the few factors that affects IBI.

Food

Brown howler monkeys are folivores and frugivorous. The diet of the brown howler monkey consists primarily of leaves and trees. Of the food sources it seems that the genera Ficus, Zanthoxylum, and, Eugenia are the most significant types consumed. Brown howler monkeys that live in higher latitudes tend to eat a lower percentage of leaves in their diet. Mature leaves are less nutritious and are more fibrous, than the preferred young leaves. A typical brown howler diet will also include mature fruit, wild figs, petioles, buds, flowers, seeds, moss, stems, and twigs
The Atlantic forest, were brown howlers tend to live, has an increasing forest fragmentation. Forest fragmentation means that there would be a decrease in potential food supplies. The brown howler’s feeding ecology, however, does not seem to be affected by the loss in habitat.