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Stable isotope investigation of insect and plant use in the diets of two Puerto Rican bat species
Citation:
Soto-Centeno, J. A., D. L. PHILLIPS, A. Kurta, AND K. A. Hobson. Stable isotope investigation of insect and plant use in the diets of two Puerto Rican bat species. Presented at 7th International Conference on Applications of Stable Isotope Techniques to Ecological Studies, Anchorage, AK, August 08 - 13, 2010.
Impact/Purpose:
We used stable isotope (δ13C, δ15N) analysis to estimate the importance of plants and insects to the diet of two nectar-feeding bats on Puerto Rico, the brown flower bat (Erophylla bombifrons) and the Greater Antillean long-tongued bat (Monophyllus redmani).
Description:
We used stable isotope (δ13C, δ15N) analysis to estimate the importance of plants and insects to the diet of two nectar-feeding bats on Puerto Rico, the brown flower bat (Erophylla bombifrons) and the Greater Antillean long-tongued bat (Monophyllus redmani). Stable carbon and nitrogen isotope values were obtained from blood of both species of bat and known plant and insect prey. We used a concentration-dependent mixing model (combination of IsoConc and IsoSource) to determine the range of feasible dietary contributions for major potential food items to the bats. We collected 67 E. bombifrons and 71 M. redmani over a period of 15 weeks at the same locality, as well as samples from seven plant species and six insect orders. Separate analyses were conducted for each species and reproductive condition (males; non-reproductive, pregnant, and lactating females). Overall, insects were an important food source for M. redmani but not for E. bombifrons, representing at least 44 to 72 percent and 4 to 16 percent of dietary biomass for the two species, respectively. Although there were broad ranges of feasible contributions of plants to the diet of M. redmani, plants represented between 0 and 56 percent of dietary biomass of all reproductive conditions. In contrast, plants were a more important food source for E. bombifrons, contributing 48 to 96 percent of dietary biomass. These results provide additional resolution to previously published findings based on fecal analysis. We propose that greater reliance on insects by M. redmani will allow populations of this species to recover more quickly after environmental disturbances, such as hurricanes.