Social organization and range use in the Yunnan snub-nosed monkey Rhinopithecus bieti

We studied social organization, behavior, and range use of the Yunnan snub-nosed monkey (Rhinopithecus bieti) at Wuyapiya (99 degrees 12'E, 28 degrees 30'N, the People's Republic of China) over 12 months between May 1992 and June 1994. The Wuyapiya band contained greater than or equal to 175 members and had two levels of social organization. At one level, the monkeys formed multifemale, one-male units (OMUs) similar to those of many other colobines. At another level, 15 to 18 OMUs traveled together in a cohesive band. Unlike the bands of other species of Rhinopithecus, the Wuyapiya band of R. bieti did not show seasonal fission-fusion, although some social behavior, such as male-male aggression, was seasonal. With regard to range use, the Wuyapiya band had a large home range and long daily travel distances compared with other colobines. Minimum range size in 1 year at Wuyapiya is 16.25 km(2), although there is no asymptote for range size as a function of observation time. Range size for the Wuyapiya band is 25.25 km(2) over the 2-year study and appeared to cover 100 km(2) between 1985 and 1994. The primary food of R. bieti at Wuyapiya is lichens, which are ubiquitous in fir frees. The multitiered social organization of R. bieti appears to result from the interaction of food resource characters with the forces of mate competition, with band sizes based on female responses to the spatial and temporal characteristics of lichens and subdivisions within bands based on male competition for mates.

Size hierarchies affecting the social interactions and growth of juvenile Japanese flounder, Paralichthys olivaceus

Japanese flounder Paralichthys olivaceus (T. & S.)juveniles were size-graded and divided into three groups (small, large, and mixture of small and large flounder), and their social interactions (feeding, aggressive attacking and activity) and growth were investigated. The growth of the small flounder was markedly suppressed by the presence of the large flounder. Large flounder did not significantly suppress the overall food intake of the small flounder but exhibited high aggressive attacking on them and consequently inhibited their activity. Size dominance showed little influence on the aggressive behavior, feeding, activity and growth of the large flounder. The large flounder could not effectively defend the food in excess during the experiments ruling out disproportional food acquisition as the primary mechanism responsible for the size hierarchy effect. Aggressive interaction of the large flounder on the small flounder might be an important cause for the growth retardation of the small flounder. In culture, size grading could markedly improve the growth and survival of the early juvenile flounder. (C) 2004 Elsevier B.V. All rights reserved.