Birds as seed dispersers of plants: their impacts on plant ecological and evolutionary dynamics

Abstract

Birds play a fundamental global role in shaping and maintaining plant populations and communities, by acting as seed dispersers. This review introduces mutualism between birds and plants, particularly endozoochory by frugivorous birds and synzoochory by some granivorous birds, and overviews the impacts of their seed dispersal on ecological and evolutionary processes of plants. First, general associations between these seed dispersal modes and avian feeding strategies are introduced, highlighting current knowledge of patterns of interaction networks between bird and plant communities. Then, plant intrinsic factors, such as fruit and seed characteristics, that are responsible for shaping plant-bird mutualism are summarized for fleshy fruits, and the ways in which the evolution of fruit and seed traits is driven by their mutualism is overviewed. In the next step, the impacts of seed dispersal by birds on plant populations and communities are explained, with emphasis on its roles in driving ecological processes at three different spatial scales (local, landscape, and regional). Lastly, future perspectives of seed dispersal research are discussed. I highlight the importance of integration of various approaches, including natural history studies on the interactions, field studies focusing on plant demography and animal behavior, and statistical modeling of large-scale empirical data, for further exploration of the ecology and evolution of plant-bird mutualism.