No abstract

Sleeping site and tree selection by Sichuan snub-nosed monkeys (Rhinopithecus roxellana) in Baihe Nature Reserve, For non-human primates to optimize their survival chances, sleeping site selection is crucial as they spend much of their time sleeping. We studied sleeping site and tree selection by a group of wild Sichuan snub-nosed monkeys (Rhinopithecus roxellana) in the temperate forests of Baihe Nature Reserve, Sichuan, China, to assess if certain site and tree characteristics were selected. We identified a total of 39 sleeping sites and 111 sleeping trees over a period of 1 year. We compared nine sleeping site and six sleeping tree variables related to the environment, habitat, and vegetation structure.We found that certain characteristics of sleeping sites and sleeping trees predicted their selection by R. roxellana. On a larger spatial scale, sleeping sites were selected based mainly on four factors: canopy height, slope direction, slope gradient, and vegetation type. They also selected sites with trees that were taller and larger, had larger crown diameters and higher bole branches. On a smaller spatial scale, they selected larger trees with larger crown diameters. The selection of these characteristics could be explained in terms of predator avoidance and thermoregulation efficiency, although it was difficult to delineate which was more important. This could be due to some characteristics of R. roxellana, that is, large groups living in temperate climates, which required a balanced strategy for sleeping site and tree selection in order to optimize their survival chances. K E Y W O R D Spredation avoidance, selective pressure, temperate forest, thermoregulation

In many mammals, males disperse more than females. Although males in some male-dispersing species form all-male groups, little is known about the association patterns or social relationships among them. Studies on male–male social relationships have primarily focused on competition over fertile females, but affiliative relationships among males have attracted much interest recently. I suggested a novel method for the classification of males based on their behaviour by principal component analysis (PCA), and investigated association patterns, and affiliative relationships in male Japanese macaques, Macaca fuscata, during the non-mating season. I observed 12 wild male Japanese macaques for 809 h during the non-mating season. The number of other animals within visual range, the amount of time that males spent in the vicinity of other animals, and the frequency of grooming interactions were examined. I classified males into two distinctive clusters (Cluster 1 and 2) according to their association and interaction patterns. Cluster 1 males associated with females and participated in grooming with them. Cluster 2 males had less visual encounters with females and did not groom them. Cluster 2 males showed proximity to other Cluster 2 males in all possible dyads. Although Cluster 2 males showed less proximity to each other than Cluster 1 males did, they frequently exchanged grooming among themselves. Cluster 2 males groomed Cluster 1 males more frequently than they were groomed by them. These results suggested that Cluster 1 were troop males, and Cluster 2 were non-troop males. Cluster 2 males had less opportunity for social interaction than Cluster 1 (troop) males, and they may form all-male groups. Males in all-male groups engaged in more frequent grooming than troop males. In addition, they groomed troop males more frequently than they were groomed. These results suggest that males could be separated by their behaviour. Male–male affiliative relationships might be influenced by within-group potential competition and imbalanced grooming appears to cause troop males to tolerate non-troop males which might be immigrated in near future.

No abstract