云南蒙自钳嘴鹳夜栖地利用及夜栖树选择

动物对夜栖地选择的灵活程度是其分布和扩散的重要因素之一。钳嘴鹳(Anastomus oscitans)为中国新分布种,要了解其扩散趋势,掌握其夜栖地需求至关重要。2015年11月至2018年7月在云南蒙自坝区,使用卫星跟踪技术对6只钳嘴鹳进行了夜栖地利用和夜栖树选择研究,结果表明:(1)钳嘴鹳可以在多种生境中夜栖,包括林地、沼泽、岛屿等。从群体水平上分析,钳嘴鹳主要夜栖于沼泽中,利用率为(51.19±12.34)%,其次为林地(31.55±11.34)%和岛屿(17.26±5.70)%;从个体水平上来看,不同钳嘴鹳的夜栖地利用方式差异较大,其中4只主要利用沼泽,而另外2只主要利用林地;(2)随机森林分析表明:影响钳嘴鹳夜栖树选择的首要因子为距觅食地距离,其次为树高、地径和最低枝高度,而人为干扰因子的影响较弱。综合来看,钳嘴鹳对夜栖地类型以及夜栖树均表现出了极强的适应性和可塑性,这可能是其能够快速扩散的重要原因之一。同时也表明夜栖树并不能成为一个有力的限制因子,钳嘴鹳有可能继续向国内的南方湿地区扩散。

Nocturnal roost use and roosting tree selection of Asian openbill (Anastomus oscitans) in Mengzi, Yunnan, China

The degree of flexibility in choosing a nocturnal habitat is one of the most important factors in animal distribution and dispersion. From November 2015 to July 2018, we carried out a study on the nocturnal roosting site use and roosting tree selection of six Asian openbills (Anastomus oscitans) using satellite tracking technology in Mengzi Basin, Yunnan Province. Our results showed that (1) the Asian openbill used three habitats as nocturnal roosting sites, comprising woodlands, swamps, and small islands in lakes. At the population level, openbills mainly roosted in swamps (51.19%±12.34%), followed by woodlands (31.55%±11.34%) and islands (17.26%±5.70%). At the individual level, there were great differences in the utilization of nocturnal roosting sites between different individuals, of which four mainly roosted in the swamp, and the other two roosted in the woodland. (3) Random forest analysis showed that the primary factors influencing nocturnal roosting tree selection of openbills were distance to foraging site, followed by tree height, ground diameter, and lowest branch height. Asian openbills were not sensitive to human disturbance. In conclusion, the studied openbills exhibited strong adaptability and plasticity in their selection of nocturnal roosting habitats and roosting trees, which may be an important reason for their rapid range expansion. Our results also indicate that nocturnal roosting trees are not a significant limiting factor for the dispersal of Asian openbills; this bird may continue to spread to wetland areas in the south of China.