Long-term Site Fidelity and Individual Home Range Shifts in Lophocebus albigena

We investigated long-term site fidelity of gray-cheeked mangabey (Lophocebus albigena) groups in Kibale National Park, Uganda. Concurrently, we monitored shifts in home range by individual females and subadult and adult males. We documented home range stability by calculating the area of overlap in successive years, and by recording the drift of each group’s monthly centroid from its initial location. Home ranges remained stable for 3 of our 4 groups (overlap over 10 yr >60%). Core areas were more labile, but group centroids drifted an average of only 530 m over the entire decade. Deviations from site fidelity were associated with dispersal or group fission. During natal dispersal, subadult males expanded their home ranges over many months, settling ≤4 home ranges away. Adult males, in contrast, typically dispersed within a few days to an adjacent group in an area of home range overlap. Adult males made solitary forays, but nearly always into areas used by their current group or by a group to which they had previously belonged. After secondary dispersal, they expanded their ranging in the company of their new group, apparently without prior solitary exploration of the new area. Some females also participated in home range shifts. Females shifted home ranges only within social groups, in association with temporary or permanent group splits. Our observations raise the possibility that male mangabeys use a finder-joiner mechanism when moving into new home ranges during secondary dispersal. Similarly, females might learn new resource locations from male immigrants before or during group fission

Predatory behavior of crowned hawk-eagles (Stephanoaetus coronatus ) in Kibale National Park, Uganda

Evaluating the nature and significance of predation on populations of wild primates has been difficult given a paucity of data regarding the phenomenon. Here we addressed this problem in a 37-month study of the predatory behavior of crowned hawk-eagles living at the Ngogo study site in Kibale National Park, Uganda. We collected prey remains underneath the nests of two pairs of eagles and census data on potential prey species to investigate prey selection and the ecological impact of predation on the Ngogo primate population. Results indicate that primates form the vast majority of all prey items. Eagles prey selectively on monkeys according to sex and species. Male primates were taken more often than females, while two species, redtail monkeys and mangabeys, were captured significantly more and less, respectively, than chance expectation. In addition, there was no bias in the age of prey: adult and non-adults were killed in numbers roughly equal to their proportional representations in the forest. Further analyses indicate that a non-trivial fraction of the entire primate population at Ngogo succumbs to crowned hawk-eagle predation each year. These results reveal both parallels and contrasts with those reported previously. Some of the parallels are due to similarities in prey availability, while contrasts are likely related to methodological differences between studies, inter- individual variations in predator hunting styles, and differences in prey abundance, demography, and behavior.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42089/1/265-49-2-3-187_10490187.pd

Tamarin polyspecific associations: Forest utilization and stability of mixed-species groups

Niche separation is likely to play a key role in the formation of mixed-species groups. Saddle-backed tamarins (Saguinusfuscicollis) were studied at three sites with different primate communities in northern Bolivia: (1) with red-bellied tamarins, S. labiatus; (2) with emperor tamarins, S. imperator; and (3) without a congeneric species. The degree of association is higher between S. labiatus and S. fuscicollis than between S. imperator and S. fuscicollis and is related to differences in forest utilization between associating pairs. Niche separation is found to be greater between S. labiatus and S. fuscicollis than between S. fuscicollis and S. imperator. The mean height and habitat utilization of S. fuscicollis does not differ greatly across the three sites, nor does the height of tamarins in and out of association. It is concluded that combined with differences in body size and dietary overlap, vertical segregation plays an important role in tamarin polyspecific associations (increasing the potential of both foraging and anti-predatory benefits) and that this is not a consequence of vertical displacement of S. fuscicollis by its dominant congeners