Investigating the Influence of Habitat Heterogeneity on Diversity of Insectivorous Birds in a River-Floodplain Mosaic
Faculty Mentor Information
Colden Baxter
Abstract
Rivers are fundamentally linked to their adjacent terrestrial ecosystems. In particular, within river-floodplains, the emergence of adult aquatic insects constitutes a resource flux for local bird communities, and the structure of this emergence varies across the mosaic of aquatic habitats within these ecosystems. In our study, we are assessing the importance of habitat heterogeneity, through its influence on patterns of insect emergence, on the overall density, species richness, and biodiversity of insectivorous birds across seven unique habitats within a Snake River-floodplain. During summer 2017, we conducted three bird point-counts monthly at each habitat, separated by 50-meter line transects. Overall, we observed higher bird abundance and richness at flowing-water habitats than standing-water habitats. In total, 16 species of insectivorous birds have been observed; several species, most notably bank swallows, song sparrows, and yellow warblers, have been ubiquitous, whereas others have been exclusively observed in specific habitats. A thought-experiment, whereby we sequentially and randomly aggregated species richness from seven habitats, revealed richness increasing curvilinearly with increasing habitat heterogeneity. We hypothesize that this pattern is linked to the asynchrony of insect emergence among habitats, such that the complexity of the mosaic sustains elevated bird diversity by providing more consistent and diverse prey resources.
Investigating the Influence of Habitat Heterogeneity on Diversity of Insectivorous Birds in a River-Floodplain Mosaic
Rivers are fundamentally linked to their adjacent terrestrial ecosystems. In particular, within river-floodplains, the emergence of adult aquatic insects constitutes a resource flux for local bird communities, and the structure of this emergence varies across the mosaic of aquatic habitats within these ecosystems. In our study, we are assessing the importance of habitat heterogeneity, through its influence on patterns of insect emergence, on the overall density, species richness, and biodiversity of insectivorous birds across seven unique habitats within a Snake River-floodplain. During summer 2017, we conducted three bird point-counts monthly at each habitat, separated by 50-meter line transects. Overall, we observed higher bird abundance and richness at flowing-water habitats than standing-water habitats. In total, 16 species of insectivorous birds have been observed; several species, most notably bank swallows, song sparrows, and yellow warblers, have been ubiquitous, whereas others have been exclusively observed in specific habitats. A thought-experiment, whereby we sequentially and randomly aggregated species richness from seven habitats, revealed richness increasing curvilinearly with increasing habitat heterogeneity. We hypothesize that this pattern is linked to the asynchrony of insect emergence among habitats, such that the complexity of the mosaic sustains elevated bird diversity by providing more consistent and diverse prey resources.