Site Fidelity in Space Use by Spider Monkeys (Ateles geoffroyi) in the Yucatan Peninsula, Mexico

Animal home ranges may vary little in their size and location in the short term but nevertheless show more variability in the long term. We evaluated the degree of site fidelity of two groups of spider monkeys (Ateles geoffroyi) over a 10- and 13-year period, respectively, in the northeastern Yucatan peninsula, Mexico. We used the Local Convex Hull method to estimate yearly home ranges and core areas (defined as the 60% probability contour) for the two groups. Home ranges varied from 7.7 to 49.6 ha and core areas varied from 3.1 to 9.2 ha. We evaluated the degree of site fidelity by quantifying the number of years in which different areas were used as either home ranges or core areas. Large tracts were used only as home ranges and only for a few years, whereas small areas were used as either core area or home range for the duration of the study. The sum of the yearly core areas coincided partially with the yearly home ranges, indicating that home ranges contain areas used intermittently. Home ranges, and especially core areas, contained a higher proportion of mature forest than the larger study site as a whole. Across years and only in one group, the size of core areas was positively correlated with the proportion of adult males in the group, while the size of home ranges was positively correlated with both the proportion of males and the number of tree species included in the diet. Our findings suggest that spider monkey home ranges are the result of a combination of long-term site fidelity and year-to-year use variation to enable exploration of new resources

Usefulness of species range polygons for predicting local primate occurrences in southeastern Peru

Species distribution maps are widely used in predicting areas of conservation concern, particularly where species distributions are poorly known. However, the accuracy of range maps for regional/local planning is questionable. We compared published putative geographic range polygons of ten primate species to their actual occupancy at 23 survey sites in southeastern Peru to assess the fine-scale accuracy of these polygons for regional conservation planning. We analyzed the proportion of sites at which each species was detected, both inside and outside of its published NatureServe [Patterson et al., Digital distribution maps of the mammals of the western hemisphere. Version 1.0. Arlington, VA, 2003] and IUCN [2008; Red List, 2008] range polygons. There were mismatches between our line-transect survey data and range polygon boundaries for nine of the ten species (from 15 to 80% cases), including both false presences and false absences. Each published dataset overestimated the presence of seven primate species and the absence of four species, though errors varied among species. Occupancy patterns of species with larger geographic ranges were no more accurately predicted than those of more narrow-range species. Regional barriers to dispersal, such as rivers, and finer-scale ecological specialization may limit the applicability of range map polygons to regional-scale conservation priority setting, even for relatively well-studied taxa. Despite the risk of errors, range polygons are still used as baseline data in conservation planning. We suggest some measures that could reduce the error risk