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BATS FEEDING RESPONSE TO LANDSCAPE URBANIZATION: A STABLE ISOTOPES APPROACH
The environmental pressures due to urbanization are responsible for diversity loss and homogenization of the animals and plants in the urban ecosystems and the adaptation to urbanization is not homogeneous between species. The flexibility of the feeding habits is one of the most important traits for native species adaptation to urban environments. We aimed to test the hypothesis that diet flexibility is determinant to use of urban areas for bats. We used δ15N and δ¹³C of the bats fur of the urban and rural habitats of the Cerrado to infer about the variation in trophic level and carbon origin of the bats diet. High values of δ15N indicate a greater consume of animal protein and high values of δ¹³C indicated a greater contribution of C4 food chain in relation to C3. Our hypothesis is that frugivorous and nectarivorous bats of urban areas will increase insect consume, with a consequent increase in δ15N, due to lower diversity of vegetal resources. We expected that insectivorous bats have lower δ¹³C in rural areas due to large extension of natural and anthropic grasses formation of the Cerrado habitats. We captured bats with mist-nets in urban and five rural areas of Distrito Federal, Brazil and the isotopic hates of bats fur was quantified with mass spectrometry. We tested the effect of the matrix (rural our urban) in the δ15N and δ¹³C of the distinct bat guilds with a MANOVA. We captured seven species of frugivorous bats, two nectarivorous and six insectivorous. The frugivorous, nectarivorous and insectivorous gilds had a clear separation in your feeding habits differing both in trophic level and carbon origin of diet. The frugivorous showing the greatest variation in feeding habit, especially in trophic level, and were the only ones that had a difference between rural and urban areas. The higher δ15N indicate that the importance of the arthropods as protein supply for frugivorous bats increase in urban area while the variation between C3 and C4 food chain tends to remain stable between matrixes. The feeding habits of the insectivorous bats did not vary between urban and rural areas, with great importance of the C4 food chain in both landscapes. Bats response to urbanization can be guild specific, while diet generalization was an important trait for frugivorous and nectarivorous bats to occupy urban matrix, insectivorous used both matrices without variation in your feeding habits.
Cerrado, frugivorous, insectivorous, nectarivorous, trophic level, Phyllostomidae
Maurício Silveira, Debora Macedo, Daniel F Ramalho, Gabriela B Nardoto, Ludmilla M S Aguiar