Data for: Neotropical mixed-species bird flocks in a community context

Mixed-species flocks are an important component of bird communities, particularly in the Neotropics, where flocks reach their highest diversity. The extent to which mixed-species flocks represent unique functional or ecological roles within communities, and how these attributes change over environmental gradients, however, is not well understood. We use a trait-based approach to examine functional aspects of flocking assemblages as they relate to those observed in the larger avian community across a 3000 m elevational gradient. Our results reveal similar ecological strategies among flocking species and the communities in which they occur, at the scale of the regional pool and across elevations. Trait variation in flocking and non-flocking assemblages is structured along two major axes defined by size- and resource-related traits. The trait space occupied by flocking species, however, represents only half (51%) that of the larger community. Similarly, the trait space of flocks across elevations is restricted compared to non-flocking species. The shared trait space across flock types represents small-bodied invertivores foraging in lower forest strata, traits associated with increased vulnerability to predation. The concentration of flocking species in functional trait space suggests high niche packing and either more overlap in ecological strategies or more finely divided niches relative to non-flocking species.混群鸟类（mixed-species flocks）是鸟类群落的重要组成部分，尤其在新热带区（Neotropics），此类鸟群的物种多样性达到峰值。然而，混群鸟类在群落中是否承担独特的功能或生态角色，以及这些特征如何随环境梯度发生变化，目前仍未得到充分阐释。本研究采用基于功能性状的研究方法，探究了3000米海拔梯度下，混群鸟类集合群的功能特征与更大尺度鸟类群落的功能特征之间的关联。研究结果显示，无论是从区域物种库尺度还是跨海拔梯度来看，混群鸟类与其所处群落中的其他物种均表现出相似的生态策略。混群与非混群鸟类集合群的性状变异，主要沿两大轴线分布，这两大轴线分别由与体型及资源获取相关的性状所定义。但混群鸟类所占据的功能性状空间仅为整个鸟类群落的一半（51%）。同样，相较于非混群鸟类，跨海拔梯度的混群鸟类所占据的性状空间更为受限。各类混群鸟类共有的性状空间，对应着在森林下层觅食的小型食无脊椎动物（invertivores），这类性状与更高的捕食者易感性相关。混群鸟类在功能性状空间中的聚集分布，表明其生态位填充度更高，且相较于非混群鸟类，它们要么具有更多重叠的生态策略，要么拥有划分更细致的生态位。