Differential mobility in two small phyllostomid bats, Artibeus watsoni and Micronycteris microtis, in a fragmented neotropical landscape

To assess the influence of habitat fragmentation on small bats, we determined home range size and mobility of the frugivorousArtibeus watsoni Thomas, 1901 and the gleaning insectivorousMicronycteris microtis Miller, 1898 by radiotracking on different-sized islands (2.7–17 ha) in Lake Gatun, Panama. The two species differed in their response to fragmentation. Home range size was highly variable in the five trackedA. watsoni, ranging from 1.8 to 17.9 ha with a mean of about 9 ha. Some individuals flew regularly between islands and/or the mainland, thereby traversing up to 180 m of open water. In comparison, home ranges of threeM. microtis were with about 3.8 ha only half as large. All ofM. microtis exhibited sedentary foraging behaviour and did not cross open water, suggesting that they might persist at least on some of the islands as resident populations. Our findings are consistent with radiotracking data from a previous study and indicate that small habitat patches are still used by small bats, provided the degree of isolation is low and that sufficient resources and larger habitat patches exist in close vicinity, potentially acting as additional feeding grounds and source populations.