Population density and use of space in howling monkeys (Alouatta villosa) in southwestern Panama.

Eight troops ofAlouatta villosa (= A. palliata) were studied for 10 weeks in a natural forest in southwestern Panama. This is one of the few extended studies on the species to be conducted in a location other than Barro Colorado Island. The 151 animals belonging to 8 troops and 6 additional isolates utilized 37 acres of forest. This population density was 21 times greater than on Barro Colorado in 1932 and 12 times than on Barro Colorado in 1967. The average troop size was 18.9 animals; the average home range was 12.1 acres. Home ranges overlapped extensively and on the average troops had only 6% of their home range for exclusive use. There were no signs that the howling monkeys were exhausting their food supply or were experiencing decreased fertility. Several factors that could function in population control are evaluated.