Feeding habits of four species of Myotis (Mammalia, Chiroptera) from Argentina

The genus Myotis is one of the most widely distributed and speciose mammalian genera, with representatives in nearly all biogeographical regions. The species of Myotis feed primarily on arthropods, except for some species that occasionally consume fish. In North American Myotis , food preference is for slow and soft-to-medium hard preys, whereas scarce or null information is available for South American species. Thirteen species of Myotis occurred in Argentina, with no previous information about its diet. The aim of this study was to analyze the diet of four species of Myotis from the Yungas forests, Argentina: M. albescens , M . dinellii , M. keaysi , and M. riparius . We also evaluated differences in diet between well-preserved and disturbed sites, sexes, and seasons. The specimens were collected in eight different localities, four well-preserved and four disturbed sites of the Yungas Forests. Through the analysis of feces, arthropod remains were identified until the lowest possible taxonomic level. Volume and frequency of occurrence percentages for each food item and the niche breadth for the species were estimated. A total of 344 pellets from 70 individuals were analyzed. The diet of these species of Myotis contained arthropods from nine orders and seven families; Lepidoptera and Diptera contributed the highest volume proportions in diet. A low niche breadth was recorded for all species. The diet was significantly influenced by site characteristics only in Myotis dinellii , being different in its consumption of arthropods between well-preserved and disturbed sites. This result showed that this species can modify its diet according to habitat quality.