Data from: Does mixed-species flocking influence how birds respond to a gradient of land-use intensity?

Conservation biology is increasingly concerned with preserving interactions among species such as mutualisms in landscapes facing anthropogenic change. We investigated how one kind of mutualism, mixed-species bird flocks, influences the way in which birds respond to different habitat types of varying land-use intensity. We use data from a well-replicated, large-scale study in Sri Lanka and the Western Ghats of India, in which flocks were observed inside forest reserves, in ‘buffer zones' of degraded forest or timber plantations, and in areas of intensive agriculture. We find flocks affected the responses of birds in three ways: (i) species with high propensity to flock were more sensitive to land use; (ii) different flock types, dominated by different flock leaders, varied in their sensitivity to land use and because following species have distinct preferences for leaders, this can have a cascading effect on followers' habitat selection; and (iii) those forest-interior species that remain outside of forests were found more inside flocks than would be expected by chance, as they may use flocks more in suboptimal habitat. We conclude that designing policies to protect flocks and their leading species may be an effective way to conserve multiple bird species in mixed forest and agricultural landscapes.

保护生物学愈发关注受人为干扰的景观中物种间相互作用的保护，例如互利共生关系。本研究聚焦于一类互利共生关系——鸟类混合群（mixed-species bird flocks），探究其如何影响鸟类对不同土地利用强度梯度下的生境类型的响应模式。本研究使用了在斯里兰卡与印度西高止山脉（Western Ghats）开展的大尺度、高重复度野外调查数据，调查覆盖了森林保护区内、退化林或用材林的缓冲带，以及集约化农业区域内的鸟类混合群观测记录。研究发现鸟类混合群从三个维度影响鸟类的响应模式：其一，合群倾向较高的鸟类类群对土地利用变化的敏感度更高；其二，由不同优势种作为群首的混合群类型，对土地利用变化的敏感度存在差异，而跟随类群对群首具有特定偏好，这会对跟随者的生境选择产生级联效应；其三，相较于随机预期，留守于非森林生境的林内物种，其参与混合群的频率更高，这可能是因为在次优生境中，这类物种更依赖混合群以提升生存效率。本研究最终得出结论：制定保护鸟类混合群及其群首物种的相关政策，或许是在森林与农业混合景观中高效保护多种鸟类类群的有效路径。