城市绿地中鸟类对小叶榕果实的取食和传播作用

Foraging and Dispersal of Birds on Ficus microcarpa Fruit in Urban Green Space

2020年9—11月借助Safari 10×42变焦双筒望远镜,采用焦点扫描法对访问小叶榕(Ficus microcarpa)果实的鸟类的取食行为(鸟类种类、取食频次、取食时间、取食量、取食方式和传播距离)进行观察,同时采用随机森林模型(random forest model)探讨鸟类功能特征对果实取食量和传播距离的影响。结果表明,小叶榕能吸引6种(1目3科)食果鸟类以整吞的方式取食其果实,其中红耳鹎(Pycnonotus jocosus)、白喉红臀鹎(Pycnonotus aurigaster)、白头鹎(Pycnonotus sinensis)是小叶榕果实的主要传播者。不同鸟类对小叶榕果实的取食频次存在显著差异(t=3.338,df=5,P=0.021),而取食量、取食时间和访问只数均存在极显著差异。7个变量(访问只数、取食方式、取食时间、翅长、尾长、体重和体长)对果实取食量的解释率为24.31%,其中鸟类访问只数与果实取食量间存在明显的正相关。鸟类体型特征变量(翅长、尾长、体重和体长)对鸟类传播距离的解释率为17.88%,其中翅长和体长均与传播距离间存在极显著正相关。说明鸟类的功能特征会影响其对小叶榕果实取食行为,进而影响其种群的自然更新。

With Safari 10×42 zoom binoculars,the focus scanning method was adopted to observe the bird foraging behavior(bird species,feeding frequency,foraging time,foraging amount,foraging methods and dispersal distance)of Ficus microcarpa fruits from September 2020 to November 2020.At the same time,the random forest model was used to explore the effects of bird functional characteristics on the number of seeds foraging amount and the dispersal distance.The results showed that Ficus microcarpa cloud attracted 6 species of frugivorous birds to swallowed the whole fruit,and Pycnonotus jocosus,Pycnonotus aurigaster and Pycnonotus sinensis were the potential seed dispersers of Ficus microcarpa.There were significant differences in the foraging times(t=3.338,df=5,P=0.021),but there was highly significant difference in the foraging amount,foraging time,foraging numbers.The interpretation rate of seven variables(number of visits,feeding pattern,feeding time,wing length,tail length,body weight and body length)on seed foraging amount was 24.31%,and there was significant positive correlation between the number of visits of birds and the seed foraging amount.The explanation rate of bird body traits(wing length,tail length,body weight and body length)to seed bird dispersal distance was 17.88%,and there was significant positive correlation between wing length and body length and dispersal distance.The result showed that the functional traits of birds would affect the foraging behavior on the fruits of F.microcarpa,and then affect the natural regeneration of its population.