Food Habits of Insectivorous Bats of Mahendra and Nagarjun Caves, Nepal

Abstract

Food habits of bats of Mahendra Cave, Pokhara and Nagarjun Cave, Kathmandu were studied using fecal analysis. Three white polythene plastic sheets (1 m x 1m size) were placed for 24 hours under the roosting sites of each cave on starting and ending days of March and September of 2011 to collect fresh bat droppings. All together 120 droppings(60 from each cave) were randomly selected, observed under stereoscope to identify insects orders and families. Altogether ten insect orders were reportedviz. Coleoptera,Diptera, Hemiptera, Homoptera, Hymenoptera, Lepidoptera, Odonata, Orthoptera, Trichoptera and Thysanoptera. The identified families were included highest in Diptera(seven families), following Coleoptera (six families), Orthoptera (five families),Hymenoptera (three families), Hemiptera (three families) and Thysanoptera (one family).In addition, spider and mites were also reported. The percentage volume of the dietcontained highest food items in Coleoptera (35.35%) and Orthoptera (24%) in Spring and Autumn respectively in Mahendra Cave. The other insects were Hymenoptera, Diptera,Hemiptera, Homoptera, Lepidoptera, Hymenoptera and Trichoptera. But in NagarjunCave, Diptera was major portion of the diet in Spring (28%) and Autumn (24%). Theother food items belong to Orthoptera, Thysanoptera, Coleoptera, Hymenoptera including spiders and mites. In Mahendra Cave, an average percentage of frequency of Coleopteran food items contained 63.33% followed by Orthoptera (46.66%) in Spring. But Orthoptera occupied(50%) followed by Coleoptera (26.66%) in Autumn. In Nagarjun Cave, Diptera was highest in both seasons. The diversity of insects consumed in Autumn and Spring in Mahendra Cave was more or less similar (H'-077 and H'-070) with Nagarjun Cave (H'-076 and H'-071) respectively.