Resource Partitioning by Two Species of Vespertilionid Bats (Lasiurus cinereus and Lasiurus borealis) Feeding around Street Lights

Partitioning of resources between Lasiurus cinereus and L. borealis was studied at a site where these species feed on insects (mostly moths) that fly around street lights. No consistent evidence of temporal resource partitioning was found in 4 years of observation. For 3 years of analysis of diets, the food-niche breadth of L. cinereus (25-35 g) was consistently larger than that of L. borealis (7-13 g). Niche overlap varied among years and was highest in a year when availability of insects was unusually low.