Since the fi rst long-term fi eld study of mantled howler monkeys carried out by Clarence R. Carpenter on Barro Colorado Island about 80 years ago, howler movement patterns and range use have been studied in several species and study sites throughout Mexico, Central, and South America. Howler monkeys often use small home ranges (<30 ha) and travel short distances each day (<1,000 m) compared with other atelines. Home range size, day range length, and patterns of use of space may vary both within-and between-species in response to differences in forest structure, patterns of resource distribution and phenology, the area of habitat available, group size, and population density. Within-species variability has been shown to increase with increasing sample size. In addition, howlers present a pattern of repetitive use of a limited number of routes to travel between feeding and V. B. Fortes