Data from: Trophic niche similarities of sympatric Turdus thrushes determined by fecal contents, stable isotopes, and bipartite networks approaches

An ecological niche has been defined as an n-dimensional hypervolume
formed by conditions and resources that species need to survive, grow and
reproduce. In practice, such niche dimensions are measurable and describe
how species share resources, which has been thought to be a crucial
mechanism for coexistence and a major driver of broad biodiversity
patterns. Here, we investigate resource partitioning and trophic
interactions of three sympatric, phylogenetically related and
morphologically similar species of thrushes (Turdus spp.). Based on one
year of data collected in southern Brazil, we investigated niche
partitioning using three approaches: diet and trophic niche assessed by
faecal analysis, diet and niche estimated by stable isotopes in blood and
mixing models, and bipartite network analysis derived from direct diet and
mixing model outputs. Approaches revealed that the three sympatric
thrushes are generalists that feed on similar diets, demonstrating high
niche overlap. Fruits from C3 plants were one of the most important food
items in their networks, with wide links connecting the three thrush
species. Turdus amaurochalinus and T. albicollis had the greatest trophic
and isotopic niche overlap, with 90% and 20% overlap, respectively. There
was partitioning of key resources between these two species, with a shared
preference for fig tree fruits - Ficus cestrifolia (T. amaurochalinus
PSIRI% = 11.3 and T. albicollis = 11.5), which was not present in the diet
of T. rufiventris. Results added a new approach to the network analysis
based on values from the stable isotope mixing models, allowing
comparisons between traditional dietary analysis and diet inferred by
isotopic mixing models, which reflects food items effectively assimilated
in consumer tissues. Both are visualized in bipartite networks and show
food-consumers link strengths. This approach could be useful to other
studies using stable isotopes coupled to network analysis, particularly
useful in sympatric species with similar niches.