Seasonal variation in the diet of the Indian pygmy bat, Pipistrellus mimus, in southern India

Abstract

We evaluated seasonal dietary variation of the Indian pygmy bat, Pipistrellus mimus, from southern India, by collecting biweekly fecal samples from beneath a maternity roost for 1 year and comparing these samples with insects collected using a light trap on the same dates. Our analyses indicate that P. mimus fed on coleopterans (26.3% volume), dipterans (20.4%), homopterans (17.5%), lepidopterans (13.6%), formicids (10.5%), hemipterans (5.7%), and isopterans (5.1%) and thus are generalized feeders. One unidentified scarabaeid species made up much of the coleopteran material and was abundant in the diet of P. mimus from late April through late August. Formicid alates were consumed throughout the year but were especially important from late July through September. Isopteran alates were important in September and October. Relative proportions of insects that were eaten differed significantly from insects captured in a light trap. In other studies, investigators interpreted such differences as evidence of selection; however, we argue that most insect traps do not provide reliable data on availability and that bats may feed in other areas than where the insects are captured. Our results indicate that ≥20 fecal pellets are needed in any one sample to determine important dietary items eaten by this species, although this sampling protocol likely overlooks minor food items.