Terrestrial behavior and trackway morphology of Neotropical bats

Bats (Chiroptera) are unique among flying animals in being the only mammal capable of powered flight and the only extant group that is quadrupedal. Extant bats demonstrate varying levels of terrestrial competency, however, the terrestrial abilities of many groups are unknown. Here we examine the terrestrial ability and resultant traces produced by bats belonging to the families Phyllostomidae and Emballonuridae. Five different subfamilies of phyllostomids and the emballonurid Saccopteryx bilineata were video recorded and analyzed for their terrestrial locomotor behaviors over a sand medium, with resultant tracks and trackways cast and measured. Behaviors and traces were compared to morphological criteria previously hypothesized to constrain terrestrial abilities of bats. Type 1 species (presumed poor walkers) generally performed only a breaststrokelike crawl and nonambulatory searching behavior, whereas the terrestrially adept Type 3 Desmodus rotundus performed a diagonal sequence walk and bound. Behaviors and traces produced by the intermediate Type 2 S. bilineata were indistinguishable from those of the Type 1 bats. Results only partially support the hypothesized morphological basis for terrestrial ability in bats and indicate that ecological differences or as yet unrecognized morphological variations may be the cause of behavioral variations in bats of the same morphotype. This research fills gaps in our knowledge of the terrestrial behaviors of nondesmodontine phyllostomid bats, and is the first study to examine the terrestrial behaviors of any species of emballonurid. Results of this research can be used for comparison to potential bat traces recorded in the geologic record, allowing for a better understanding of bat evolution and dispersal patterns.