Group Size and Composition of Black-and-White Snub-nosed Monkey (Rhinopithecus bieti) Estimated by Faecesof Sleeping Sites at Baima Snow Mountain

This study was designed to introduce a new method of estimating group size and composition of black-andwhite snub-nosed monkeys （Rhinopithecus bieti ） on the basis of faecal amount at sleeping sites at Mt. Baima Nature Reserve. The monkeys spend nights in the form of one-male, multi-female units （OMUs） and all-male units （AMU）, and their faecal pellets can be classified into three categories： adult males （the largest）, adult females （moderate） and immatures （the smallest） based on their size. Total pellets were counted under sleeping trees used for two nights at Nanren village （99°04′E, 28°34′N, northwest of Yunnan Province, China） in each of four seasons in 2000- 2001. Moreover, data on group composition were collected when the monkeys were passing through an open gully in November 2001. Since the number of adults in OMUs shows a positive significant correlation with the amount of pellets amount in each season, the mean number of feces produced per night per individual is the slope of the regression lines. Thus, group size and composition can be relatively reliably and accurately estimated by the faeces under trees compared with the previous methods of estimation, including the use of monkeys＇ activities and tracks such as broken branches on steep slopes, in deep gorges and under lower visibility. The use of pellets for population estimates displayed 9.4% deviation in regards to population size of adult females. Some causes of the bias were also discussed. The method might be applicable to other monkey groups of this species if their habitats and main foods are similar to those of the study group.

Distribution of sleeping sites of the Yunnan snub-nosed monkey(Rhinopithecus bieti)in the Samage Forest,China

Sleeping site locations are important to free-ranging primate groups.Sites are strategically selected by primates so as to optimize security,comfort and foraging efficiency.Data were collected on the distribution of sleeping sites of the Yunnan snub-nosed monkey(Rhinopithecus bieti)between Sep 2005 and Sep 2006 at Gehuaqing in Baimaxueshan Nature Reserve,China.We identified 54 sleeping sites,which were used 137 times during the study period.These sleeping sites were distributed throughout the monkey group’s total home range.R.bieti preferred certain sleeping sites over others:63%of the sleeping sites were used 2 or more times in 13 months.Groups reused locations in an unpredictable long-term pattern,but avoided using the same sleeping site on consecutive nights.To reduce the time and energetic costs of travel,monkeys preferred sleeping near commonly used feeding sites.We recorded 124 feeding sites in the home range,which were used 174 times.A total of 27 sleeping sites were also feeding sites,and all remaining sleeping sites were close to feeding sites.There was a positive correlation between the intensity of use of sleeping sites and feeding sites.The present study suggests that the availability and the location of immediate sources of food is a key factor in the choice of sleeping sites.

Sleeping site use of the white-headed langur Trachypithecus leucocephalus： The role of predation risk, territorial defense, and proximity to feeding sites

We collected data on sleeping site use from two groups of white-headed langurs Trachypithecus leucocephalus living in Fusui Nature Reserve, China between August 2007 and July 2008. This information was used to test several hypotheses regarding ultimate causes of sleeping site use in this primate. White-headed langurs slept either in caves （17 sites） or on a cliffledge （one site）. They used all sleeping sites repeatedly, and reused some of them on consecutive nights; three nights was the longest consecutive use of any one sleep site. We suggest that langurs use sleeping sites to make approach and attack by predators difficult, and to increase their own familiarity with a location so as to improve chances for escape. Langurs＇ cryptic behaviors with an increased level of vigilance before entering sleeping sites may also help in decreasing the possibility of detection by predators. Group 1 spent more sleeping nights in the central area of their territory than expected; in contrast, group 2 spent more sleeping nights in the periphery of their territory, which overlaps with that of another groups, than expected. The position of sleeping site relative to the last feeding site of the day and the first feeding site of the subsequent morning indicated a strategy closer to that of a multiple central place forager than of a central place forager. These results suggest that territory defense and food access may play an important role in sleeping site use of white-headed langurs [Current Zoology 57 （3）： 260-268, 2011].

Characteristics of night-time sleeping places selected by golden monkeys(Rhinopithecus bieti)in the Samage Forest,Baima Snow Mountain Nature Reserve,China

We examined the criteria for sleeping place selection in a social band of Rhinopithecus bieti(black-and-white snubnosed or golden monkeys)living in the mountainous Samage Forest,Baima Snow Mountain Nature Reserve,Yunnan,China.We performed principal component analysis and found that slope aspect,tree height and trunk diameter were likely key variables influencing selection of sleeping places.Sleeping sites were preferentially located in mixed deciduous/conifer forest.The monkeys slept exclusively in evergreen trees,of which 82%were conifers(mostly Picea likiangensis and Tsuga dumosa)and 18%evergreen oaks(Cyclobalanopsis oxyodon and Quercus spp.).Sleeping trees were tall(mean 30.5 m),had high boles(mean 18.4 m),large diameters(mean 62.6 cm)and large crown areas(mean 57.9 m^(2)).A comparative analysis of phytological and architectural features between trees in“sleeping site plots”(n=18)and trees in“non-sleeping-site plots”(n=66)revealed that diameter,crown surface area and tree height were significantly(P<0.01)larger in the former compared with the latter.All investigated roosting sites were situated on steep mountain slopes.Valleys and mountain ridges were avoided.We also detected re-use of roosting sites on several occasions,but not on consecutive nights.It is most likely that a mix of factors(stability of trees,access to food,unit cohesion,monitoring potential)explains the pattern of sleeping site preference,but predation at night seems to be only slightly important.Climate appears to have a profound influence on patterns of sleeping site selection in the monkeys’harsh temperate habitat.This is demonstrated by the monkeys’preference for mixed forest at medium elevations over montane fir forest at high elevations and slopes instead of ridges,with reduced exposure to wind and precipitation inherent in the former.We also emphasize the possibly substantial role that non-environmental factors(the nature of social organization and socio-behavioral strategies)play in determining sleeping site use in R.bieti and other primates.