滇金丝猴夜宿树的选择及夜宿地的利用方式

Sleeping tree species selection and patterns of sleeping site use in a wild group of Yunnan snub-nosed monkeys(Rhinopithecus bieti)at Jinsichang,Lijiang,China

野生灵长类夜宿地的利用方式可以明确地反映一个物种特有的生境利用方式和生存之道。2003年12月至2004年10月,我们利用可自动脱落GPS无线电项圈对云南省丽江市金丝厂的一个滇金丝猴(Rhinopithecus bieti)群体的活动进行了持续跟踪记录。本研究着重于对所研究猴群夜宿树的选择和夜宿地的利用方式的考查,并结合可能影响夜宿地选择和利用的环境因素,比如天气、季节、日均温度等做了系统分析。研究群计有180余只个体,家域面积约27.8 km^(2)。GPS项圈记录到夜宿树的有272个夜晚,由此我们确认了131个夜宿地。其中70个(54.3%)夜宿地仅利用了一次,剩余的则不同程度地多次利用(2~9次)。在这些重复利用的夜宿地中,持续利用同一夜宿点的情形共发生了19次,其中连续3个夜晚在同一夜宿地过夜的现象出现了3次,剩下的16次是连续利用同一夜宿地2次。这种连续利用同一夜宿地的情况占重复利用同一夜宿的7.0%,发生频率不高,而且几乎都出现在冬季(84.0%)。滇金丝猴对于同一夜宿地的重复造访的时间间隔约50 d。一旦发生连续重复利用的情况,猴群当天的移动距离显著缩短(527 m vs.884 m),降低了群体移动所必需的能量消耗。明显地,滇金丝猴夜宿点的选择受其当天下午和第二天早上觅食点的位置的影响。鉴于较大的群体和明显回避夜宿地重复利用的特性,提示这是猴群对家域内食物分布的行为响应,避免对同一地点的过度利用造成食物的不足。采用大量(131个)而分散的夜宿地利用方式会保证猴群能够获得充足的食物供应。此外,相较于其他树种,滇金丝猴更喜欢在云南铁杉(Tsuga dumosa)树上过夜,而且尽量不以夜宿点作为觅食点,可能与卫生和安全有关。

Studies of sleeping site use in wild primates offer insights into species-specific patterns of ranging and habitat utilization.From December 2003 to October 2004,we recorded sleeping site use in a wild group of 180 Yunnan snubnosed monkeys(Rhinopithecus bieti)at Jinsichang,Lijiang City,Yunnan Province,China.A programmed auto-released GPS collar was used to track the movements of the monkeys.We obtained 272 GPS nighttime locations and visually confirmed 131 sleeping sites within the group’s 17.8 km^(2) home range.Seventy(53.4%)sleeping sites were used on only one occasion,whereas the remaining 61(46.6%)were used between 2 and 9 times over the 11-month tracking period.On three occasions the monkeys slept in the same site during three consecutive nights and on 16 occasions they reused the same sleeping site on two consecutive nights.Re-use of sleeping areas over consecutive nights accounted for only 7.0%of our sample and principally occurred during the winter months of November-April(84.0%compared to the rest of the year).The average time interval between the reuse of the same sleeping site was 50 days.Daily travel distance was significantly shorter(527 m vs.884 m)when sleeping sites were reused on consecutive nights.Sleeping sites of Yunnan snub-nosed monkeys were used in relation to their proximity to late afternoon and next day early morning feeding sites.Given the large size of the snub-nosed monkey group,we argue that limited reuse of sleeping sites represents a pattern of habitat exploitation characterized by the avoidance of recently visited areas and a foraging strategy of searching for scattered but highly productive feeding sites that are widely distributed across their home range.Furthermore,the monkeys highly selected Himalayan hemlock(Tsuga dumosa)as sleeping trees and rarely fed in trees that were used as sleep nighttime sleeping sites.