The diet and activity of a population of Alouatta pigra were compared before and immediately after a major hurricane to begin to explore how the monkeys cope with severe habitat destruction. Focal animal data were collected from January to April (dry season) for two seasons before (368 h) and one season after the storm (149 h) on a population of black howlers in Monkey River, Belize. During the first dry season after the storm, the monkeys changed their diet in direct accordance with the availability of food. The absence of fruit and flower production and the increase in new leaf availability forced the monkeys to adopt a completely folivorous diet. The activity budget of the monkeys also changed, and they spent more time inactive, which may be linked to the change in the distribution and type of food available. They also spent less time in social interactions, which may be due to the lower number of juveniles in the population or to the formation of new groups between unfamiliar individuals following the hurricane. The ability to live for long periods of time on leaves alone has allowed the remaining population to survive in the short term.