Individual Specialization of Frugivorous Birds Within a Plant–Frugivore Community: A Network Approach

Network approaches are commonly used to study mutualistic interactions between frugivorous birds and plants at the community level. However, most fruit–bird networks aggregate individual data and rely on species-level traits, often overlooking intraspecific variation. Here, we downscale a fruit–bird network to the individual level to evaluate intraspecific diet variation and individual specialization in the four main frugivorous passerine species of an island community. Fruit consumption was identified from fecal samples collected from mist-netted birds and individuals’ diets were modeled with a Bayesian approach. Intraspecific diet variation was quantified using the E and NODF indices, individual specialization using the Psi index, and clustering of individuals sharing fruit resources using the Cws index. We detected low intraspecific diet variation and individuals’ diets were not nested. Individual specialization was mainly related to recapture of individuals and weakly related to phenotypic traits. Clustering mainly involved heterospecific individuals whose diets matched plant fruiting phenology during the capture period. Accordingly, future community-level studies addressing the role of mutualistic interactions in biodiversity maintenance may benefit from integrating network approaches with complementary information on interindividual and interspecific competition.