群体大小和觅食环境变化对东黑冠长臂猿日移动距离的影响

日移动距离是反映动物觅食努力的重要指标之一,相关研究有助于了解动物对生境的适应策略,对濒危物种的保护至关重要.东黑冠长臂猿(Nomascus nasutus)是一种极度濒危的树栖小型类人猿,主要生活在一夫二妻制的群体中,平均群体大小6.3只,目前对于该物种的日移动距离仍然缺乏足够的科学研究.我们以广西邦亮长臂猿国家级自...

The influence of group size and foraging environment on the daily path length of a critically endangered primate Nomascus nasutus

Daily path length can reflect animals'foraging efforts and offer insights into their foraging strategy, which is essential for implementing effective conservation plans for endangered species.The Cao Vit gibbon(Nomascus nasutus) is a small, critically endangered arboreal ape living in polygynous social groups(average group size 6.3).Research on its daily path length related to foraging habits is still limited.During two distinct periods, one from April 2008 to December 2009 and the other from October 2016 to August 2017, we followed two gibbon groups(G1 and G4) in Bangliang National Nature Reserve, Guangxi Province, China.We collected feeding behavioral and dietary data using instantaneous scan sampling at 5 min intervals on gibbon groups and mapped the gibbon groups' positions every 30 minutes.A total of 157 full-day observations were used to analyze the dietary changes and calculate the gibbons' daily path lengths.The gibbons changed their diet significantly in the two observation periods, and we found that they traveled on average 1 373 m per day(range:354-2 837 m), similarly to monogamous gibbon species living in low-latitude areas with smaller group sizes(3.8 in average).These findings indicate that, despite Cao Vit gibbons' relatively bigger group sizes, their daily foraging effort is not higher than other species, conflicting with the ecological constraints model.The availability of larger food patches, lower inter-species competition, and low group density might be the main reason for allowing Cao Vit gibbons to survive in bigger groups without increasing foraging efforts.Furthermore, the gibbons fed more fruits and traveled longer distances when anthropogenic disturbances were lower, while they significantly decreased their movements during the fruit-scarce dry season.This points to a potential energy conservation strategy employed by Cao Vit gibbons as an adaptation to cope with limited high-quality food.The large amount of data provided by the present work significantly amplified our understanding of Cao Vit gibbons travel patterns related to their foraging behavior when facing food scarcity, and improved the scientific knowledge that fosters the conservation of critically endangered wildlife.