Habitat selection by translocated black howler monkeys in Belize

Habitat selection by translocated black howler monkeys (Alouatta pigra) was studied in Belize, Central America. Ranging patterns of two recently translocated groups were contrasted with those of two groups in the same area with established home ranges, on a yearly and monthly basis. All groups concentrated their activities along stream beds at elevations below 200 m. Newly translocated groups increased the percentage of their monthly ranges in riverine areas (within 100 m of a water source) over the year of the study (with the exception of the last month) while established groups did not. Areas used more than five times by the monkeys contained larger trees and a greater relative coverage of major food species than low-use areas even though they had a lower overall species richness and diversity. These monkeys may be selecting habitat within the forest based upon vegetative differences and ranging patterns may be affected by patterns of food availability. All correspondence to: Linde E. T. Ostro. Tel: 718 220 6825; Fax: 718 220 7114; E-mail: [email protected]. details of the translocation, see Horwich et al., 1993; Koontz et al., 1994; Koontz & Ostro, 2000). The CBWS consists of 400 km2 of continuous evergreen and semievergreen broadleaf tropical forest (Kamstra, 1987). While CBWS contains the watershed of two river systems in the East and West Basins, like Tikal the forest lacks clearly defined riparian or gallery forest. The monkeys were released into the East Basin: the watershed of the South Stann Creek river. Elevations within CBWS range from 80 m to 1120 m above sea level (a.s.l.). From May 1994 to May 1995 habitat selection by two groups of recently translocated monkeys and two groups with established home ranges in CBWS was studied. Our intention was to characterize and compare the areas that the monkeys used extensively with those areas that were explored and subsequently not used. We were particularly interested in the effects of elevation and proximity to watercourses on the ranging patterns of the monkeys in CBWS. It was hypothesized that the use of habitat below 120 m would be disproportionate to the amount of lowland habitat in the study area, and that the use of riverine areas would be disproportionate to the amount of riverine habitat in the study area. Furthermore, it was predicted that areas used most by the monkeys would be characterized by differences in vegetation. It was also predicted that if the groups were selecting particular habitat types, recently translocated (new) groups would increase the percentage of their monthly range spent in these habitats over time, but established groups that were translocated 2 years previously, would not show such an increase.