TERRITORY SIZE AND DEFENDABILITY IN PRIMATES

Mitani and Rodman (1979) showed that a simple measure of the defendabi lity of the range area could differentiate fairly successfully between territorial and non-territorial species of primates. Their analysis h as, however, been much criticised on the grounds that it considered on ly the day journey length and the diameter of the range area. We devel op a number of more realistic indices of territory defendability that take into account both the length of the boundary to be defended and t he detection distance as well as linear measures of range size. These indices (a) discriminate between territorial and non-territorial speci es more successfully than the Mitani-Rodman index and (b) allow the re sults to be extended to species which do not forage in cohesive groups . However, our results suggest that the Mitani-Rodman analysis was in many ways correct.