Grueter Cyril C, Li Dayong, Ren Baoping, Li Ming
School of Anatomy, Physiology and Human Biology, University of Western Australia, Crawley, Australia.
Integr Zool. 2013 Dec;8(4):335-45. doi: 10.1111/1749-4877.12023.
Extant colobines represent a predominantly arboreal primate radiation, but there are outliers such as some species of snub-nosed monkeys (Rhinopithecus spp.) that utilize both arboreal and terrestrial substrates. We quantified the degree of terrestriality and the distribution of individuals across canopy levels, the extrinsic and intrinsic determinants and constraints of strata association as well as use of postures in relation to behavior and food sources in a wild population of Yunnan snub-nosed monkeys (Rhinopithecus bieti) in the Samage Forest, China. The subjects spent 80.5% of the observation time in the trees and 19.5% on the ground. Ground use occurred most frequently in the context of travelling (61%) and less often in the context of feeding and resting (30% combined). Adult males frequented the ground significantly more often than other age-sex classes. Age-sex differences were also apparent in substrate preferences, which likely reflect body weight constraints. Adult males were significantly more associated with solid substrates and less with terminal branches than adult females and juveniles. Juveniles were seen more often on unstable ground (i.e. on thin and oblique branches) and in the upper canopy. Substrate use also varied with behavior: feeding was much more common in the upper stratum, outer canopy, on highly inclined and thin branches, as compared to resting. Severe weather also influenced canopy use in that tree crowns were used less often during periods of snowfall. The most frequently exhibited resting and feeding postures was sitting. Standing and suspensory postures were most often used in the context of feeding on lichens.
现存的叶猴主要是树栖灵长类动物，但也有一些例外，比如一些仰鼻猴属（Rhinopithecus spp.）的物种既利用树栖环境，也利用陆地环境。我们对中国云南白马雪山森林中滇金丝猴（Rhinopithecus bieti）野生种群的陆地活动程度、个体在树冠层中的分布、层间关联的外在和内在决定因素及限制，以及与行为和食物来源相关的姿势使用情况进行了量化。研究对象80.5%的观察时间是在树上度过的，19.5%是在地面上。地面活动最常出现在移动过程中（61%），而在进食和休息时出现的频率较低（两者合计为30%）。成年雄性在地面活动的频率明显高于其他年龄 - 性别类别。年龄 - 性别差异在底物偏好上也很明显，这可能反映了体重限制。与成年雌性和幼年个体相比，成年雄性与坚实底物的关联更为显著，与末梢树枝的关联则较少。幼年个体更多出现在不稳定的地面（即细而倾斜的树枝上）和树冠上层。底物使用情况也因行为而异：与休息相比，进食在上层、树冠外侧、高度倾斜和细的树枝上更为常见。恶劣天气也会影响树冠层的使用，降雪期间树冠的使用频率较低。最常呈现的休息和进食姿势是坐着。站立和悬吊姿势最常用于取食地衣的情境中。
