Meeting Abstract

100.2  Saturday, Jan. 7  The effects of reproductive state on dietary shifts in Jamaican fruit bats Artibeus jamaicensis ORR, T.J.*; HAMMOND, K.A.; ORTEGA, J.; Univ. of California, Riverside; Univ. of California, Riverside; Politécnico Nacional, D.F., Mexico

Bats display an impressive diversity of dietary niches. This variation includes frugivory in many neotropical bats. Fruit however, is nitrogen poor and during reproduction frugivorous bats are expected to be nitrogen-limited. Insects provide a good source of protein and many otherwise frugivorous bats have been observed including insects in their diet faculatively. It has remained unclear if this incorporation is seasonally or physiologically determined. We expected females of Artibeus jamaicensis, the Jamaican fruit bat, and the closely related Mexican endemic species Artibeus hirsutus, the hairy tailed fruit bat to supplement their frugivorous diets with insects during the nitrogen demanding periods of late stage pregnancy and lactation. We measured naturally occurring stable isotopes of nitrogen (δ15N) to examine the roles of fruit vs. insects in the diets of these two bat species. Because isotopic composition of an animal’s tissues reflects its diet we evaluated δ15N of plasma to assess trophic level differences among individuals of variable reproductive states. Our data indicate that males exhibited the narrowest dietary breadth-widths and lactating females the greatest. The highest δ15N values and consequently largest portion of insect usages were noted in pregnant females. As expected, pups were enriched relative to their mothers. Our isotopic data combined with dietary (seed and fecal) samples from under roosts indicate that, while fruits remain an important part of these bats diets, insects may be an extremely valuable source of nitrogen during reproduction. We discuss individual dietary differences observed in Puebla and Morelos, Mexico and the importance of this variation as well as the prevalence of dietary supplementation with insects among frugivorous bats in general.