Manoeuvrability and ecological segregation in the little brown (Myotis lucifugus) and Yuma (M. yumanensis) bats (Chiroptera: Vespertilionidae)

Abstract

The abilities of two species of sympatric insectivorous bats, Myotis lucifugus and M. yumanensis, to negotiate a series of obstacle courses were measured. One hundred percent of the tested M. yumanensis were capable of negotiating their way through vertical strings 0.21 m apart, as compared with 30% of the tested M. lucifugus. A significant difference between the two species was found for this flight performance parameter, and this difference was found to be correlated with wing loading and wingspan. Myotis yumanensis has a lower wing loading and a lower wingspan than M. lucifugus, which probably explains the differences in manoeuvrability between the two species. An attempt was made to relate this difference to differences in the foraging behavior of the two species, but this was not possible, probably because of the high degree of morphological and behavioural overlap between the two species.