This report is based on the feeding behavior of one black howler monkey troop (Alouatta pigra). Observations were made during an annual cycle (February 2002 to January 2003) in a highly fragmented habitat (0,164 ha) in the Leona Vicario ranch, Balancan, Tabasco, Mexico. The present study is the first systematic report for the state of Tabasco on the diet of this primate specie. By means of the Focal Animal method, behavioral observations of the activities of the troop (n=9, 3 AM, 2 AF, 2 J, 2 I) were recorded (n = 499 h), of which 19.6 % (96 h 55 min) were recorded developing feeding behavior. In the study area we recorded the consumption of 15 spp. (55.5 %) of a total of 27 plants species in the site. The number of species used per month varied from 5 to 12 (mean = nine species). The Young leaves and the mature fruits were the main vegetal parts consumed by the howlers (70.8 % and 11.4 % respectively). Between the different species consumed by the howlers, only few were preferred by the troop (X2= 25060, p>>0.001, gl =14) and these species had low densities in the study site (vgr. Andira inermis with 0,007 ind/ha). Under these disturbance conditions, howler's consumption on different plant parts throughout the year shows us a high nutritional flexibility. This strategy allows the black howler monkeys to survive in the study site in the short term; nevertheless, it is very important to investigate the consequences population level in the future.
