Habitat fragmentation shapes natal dispersal and sociality in an Afrotropical cooperative breeder

It remains poorly understood how effects of anthropogenic activity, such as large-scale habitat fragmentation, impact sociality in animals. In cooperatively breeding species, groups are mostly formed through delayed offspring dispersal, and habitat fragmentation can affect this process in two opposite directions. Increased habitat isolation may increase dispersal costs, promoting delayed dispersal. Alternatively, reduced patch size and quality may decrease benefits of philopatry, promoting dispersal. Here, we test both predictions in a cooperatively breeding bird (placid greenbul, Phyllastrephus placidus) from an Afrotropical cloud forest archipelago. Males born in fragmented forest dispersed about one year earlier than those born in continuous forest. Contrary to females, males also started to reproduce earlier and mostly settled within their natal patch. Females only rarely delayed their dispersal for more than one year, both in fragmented and continuous forests. Our results suggest t...

目前学界对人类活动（如大规模生境破碎化（habitat fragmentation））如何影响动物社会性的机制仍缺乏充分认知。在合作繁殖物种（cooperatively breeding species）中，其社群多通过后代延迟扩散形成，而生境破碎化可通过两种截然相反的路径对这一过程产生影响：生境隔离程度提升会增加扩散成本，进而推动后代延迟扩散；反之，生境斑块面积缩小与质量下降会降低恋巢收益（benefits of philopatry），最终促进个体扩散。本研究以非洲热带云雾林群岛中的合作繁殖鸟类——平和绿鹎（placid greenbul，学名*Phyllastrephus placidus*）为研究对象，对上述两项预测进行验证。研究结果显示，生于破碎化生境的雄性个体，其扩散时间较连续生境中的雄性个体早约1年；与雌性个体不同，雄性的繁殖起始时间也更早，且大多定居于出生斑块内。无论在破碎化还是连续生境中，雌性个体极少延迟扩散达1年以上。本研究结果表明……