Feeding and general activity patterns of a howler monkey (Alouatta palliata) troop living in a forest fragment at Los Tuxtlas, Mexico

The feeding behavior and general activity patterns of a howler monkey troop living in a 3.6 ha forest fragment were studied at Los Tuxtlas, Mexico, fo r an annual cycle. Monthly samples of their feeding behavior indicated that they used 52 species of 24 plant families as sources of food. Of these, 67 % were trees, which accounted for 96% of total feeding time recorded. Ten s pecies of Moraceae, Cecropiaceae, Anacrdiaceae. and Sapotaceae contributed to 70% of the trees used and to almost 90% of feeding time. The number of p lant species used per monthly record varied from 7 to 31 with an average of 19.9 species. Young leaves and ripe fruit were the principal items in the monthly diet of howlers and average percent of time spent consuming these p lant parts was 46.7% and 34.8%, respectively. The use of tree species was f ound to be associated to their importance value and to their pattern of spa tial dispersal in the study site. Availability of young leaves was fairly c onstant from month to month, but it presented a seasonal pattern, and there was a significantly lower number of tree species bearing ripe fruit throug h the year with brief pulses of production. The monthly activity pattern wa s found to be related to variations in the availability of young leaves and ripe fruit as well as to the values of the intermonthly overlap in plant s pecies used. Resting and feeding presented a bimodal pattern of occurrence throughout the day that seemed to be related to variations in maximum ambie nt temperatures. Results are discussed in Light of the small size and shape of the forest fragment inhabited by the howler troop. (C) 1999 Wiley-Liss, Inc.