云南拉沙山黑白仰鼻猴群体规模对冬春季日移动距离和活动时间分配的影响

Effect of group size on daily travel distance and activity budget of Rhinopithecus bieti during the winter and spring seasons in Mt.Lasha,Yunnan,China

生态限制模型(Ecological constraints model)认为随种群规模增加,灵长类种群会增加日移动距离、移动时间和取食时间,减少休息时间。果食性灵长类为取食斑块分布的高质量食物资源(如果实)而存在群内分摊竞争(Within-group scramble competition),很好地验证了生态限制模型。为了检验温带叶食性灵长类是否适用于生态限制模型,于2018年12月—2019年5月,在云岭省级自然保护区拉沙山采用20 min瞬时扫描取样法收集猴群日活动时间分配,每隔30 min在地形图(1∶50 000)上记录猴群活动位点收集其日移动距离数据,比较了同域分布的黑白仰鼻猴较大群(170只)和较小群(100只)冬春季的日移动距离和活动时间分配差异。结果表明,春季和冬季黑白仰鼻猴较大群比较小群的日移动距离更远;虽然春季较大群减少了社交时间、增加了移动时间,但是冬季两群活动时间分配无差异。此外,春季,较大群相比较小群的成年和青少年个体减少了社交时间,成年雌性增加了移动时间;冬季,较大群仅成年雌性增加了休息时间,其他不同年龄—性别组的活动时间分配无差异。本研究证实了黑白仰鼻猴群内存在分摊竞争,且春季分摊竞争的强度更高,符合生态限制模型。此外,群体规模对成年雌性的活动时间分配影响较大,这与其妊娠期相对高的营养和能量需求有关。

The ecological constraints model(ECM) proposes that when the population size increases,primates will increase daily travel distance,moving time,feeding time,reduce resting time.In line with the ECM,within-group scramble competition occurred within groups of frugivorous primates due to patch-distributed and high-quality food resources(such as fruits).During the period from December 2018 to May 2019,we collected data on daily time budget of both a larger group(170) and a smaller group(100) of Rhinopithecus bieti living in the same area through instantaneous scanning sampling every 20 minutes.Locations were recorded on a topographic map(1∶50 000) every 30 minutes to collect daily travel distance data in Mt.Lasha of Yunling Provincial Nature Reserve.We then analyzed differences in daily travel distance and time budget in order to test whether temperate folivorous primates follow the ECM.The results indicate that the larger group had longer daily travel distance than the smaller group in spring and winter,reduced socializing time and increased moving time in spring.However,no difference in time budget between the two groups was found in winter.Moreover,all age-sex classes of individuals in the larger group decreased the time spent in socializing activities in spring,but adult females increased the time spent in moving.In winter,adult females in the larger group increased resting time,but there were no differences in time budget of other age-sex classes of individuals between the groups.Our study demonstrates that there was within-group scramble competition in R.bieti,and much intensity of scramble competition was found in spring than in winter,which was in accordance with the ECM.In addition,the group size had a greater influence on the time budget of adult females,which was related to their relatively high nutritional and energy needs during pregnancy.