| A group of the Yunnan snub-nosed monkey (Rhinopithecus bieti) at Xiangguqing (27°37'N,99°22'E) was investigated on its activity budgets, sleeping behavior and diet in Baimaxueshan National Nature Reserve (27°24'～27°37'N,98°22'～99°25'E), Yunnan Province from June 2008 to May 2009, via direct observation and instantaneous scan sampling method. The group size added up to 480 in 2008.The results showed that there were two feeding peaks of the study group of R.bieti presented during 0700-1100 and 1600-1800, with a midday resting peak. Seasonality influenced activity budgets of the study group a little bit. Xiangguqing group spent 38.8% of its daytime in feeding,27.4% in moving,20.9% in resting, and 12.9% in other activities, respectively. Their time budgets showed significant seasonal variation:they spent a greater proportion of time in feeding and resting in winter than the other seasons. In summer, they spent more time in moving than the other seasons. They devoted more time 15.7% to other activities in copulation season. Time budgets also differed among different age-sex classes: adults spent a greater time 42.3% in feeding, and immatures in resting 25.1%. The cost of gestation and lactation might increase the nutritional requirements of adult females, they spent more time feeding. Adult males spent more time on other activity than adult females did. Because of their activity capability, infants were found spending more time 30.8% resting than adults and juveniles. Day length influenced time budgets of R.bieti significantly. For example, the study group foraged longer during a longer day (r=0.874,p=0.000). Furthermore, the monkey would feed longer time when the monthly mean temperature was higher (r=0.783, p=0.003). Precipitation did not influence time budgets of the study group at all (p>0.05). The study group would reduce its moving time (r=-0.902,p=0.000) and rest more time (r=0.860, p=0.000) when lichens were fed as most part of its daily diet. It increased their moving time when young leaves were abundant (r=0.832,p=0.001) in spring and bamboo shoots grew in summer.It took 20.2 minutes for the whole group to enter into sleeping trees and fall asleep, and this duration was not markedly different seasonally. However, sleeping time during the whole night was significantly different from season to season. The yearly mean night-sleeping time was 11.5 hrs, the shortest one was 10.1 hrs in summer, and the longest,13.0 hrs in winter. A positive correlation between sleeping time and the night length was detected. Night-sleeping time was longer when it was snowing than it no-snowing in winter; however, it was affected by sunning and raining in summer. The mean time was 12.3 min from the first active individual to most individual's activity in the morning. The order of entering sleeping tree was markedly in one-male unit (OMU). Females often entered the sleeping tree firstly; male always entered it finally. However, the order was not evidently when the members leaved the sleeping trees in the morning. Two kinds of sleeping behavior were recognized in R. bieti: lone sleeping and huddle sleeping. Adult males in one-male units (OMUs) slept alone in most time at night (89.2% out of the whole frequency records). Such a sleeping display of adult male might be advantageous for foster care or manage the family remembers in space. Huddling sizes in sleeping were significantly different among four seasons, which was the largest (3.05) in winter. With the declining of temperature, huddling sizes tended to increase. Huddling when sleeps under cold conditions can protect the animals from low temperature. Thirteen kinds of huddling sleep among the different age-sex categories were recorded. Huddling between female-juvenile (26.5%) and female-infant (15.6%) were the most common format, adding to 42.1 per cent in total. Juveniles often huddled sleeping (13.9%) each other at night. Sometimes all remembers in one OMU huddled sleeping together. Huddling sleep functions protection immature individual from predation and can reflect social relationships of R. bieti.The study group of R. bieti ate 105 plant species of 42 families at Xiangguqing. Foods distributed through conifer tree, broad leaf deciduous and evergreen tree, shrub, vine and herb. The monkey was observed predating insects, birds, bird eggs, and soil infrequently. Dietary diversity varied seasonally:the lowest in winter and the most abundant in spring. They fed on the highest diversity of plant species in summer, and they ate the least feed species in winter. Monkeys feed on lichens year round. The annual diet consisted of 50.6% lichens,16.3% mature leaves,10.5% fruits and seeds,8.4% young leaves,7.9% bamboo shoots,3.0% buds, 1.9% flowers, and 1.3% other items. They consumed more young leaves in spring, and more fruits and seeds in autumn. Bamboo shoots became one of primary foods of R. bieti in June and July but bamboo leaves are consumed throughout the year. They preferred broad-deciduous leaves to evergreen ones. The top 10 food families accounted for 39.6% of the total feeding time. The feeding time added to 17.6% for Rosaceae. They showed high selectivity in Sorbus spp. and Prunus spp. Food choice and utilization by R.bieti were significantly influenced by the spatio-temporal distribution of those diversity foods.
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