The acoustic gymnastics of the dwarf dog-faced bat (Molossops temminckii) in environments with different degrees of clutter

Molossops temminckii is the only species of the Molossidae capable of exploring background-cluttered space. We tested the hypothesis that M. temminckii uses the clutter rejection strategy in cluttered environments and determined whether the echolocation calls of this species show large-scale geographic variation. We recorded echolocation calls of 10 individuals of M. temminckii using 4 treatments with different degrees of clutter. We compared individuals recorded in Venezuela with individuals recorded in Brazil to verify geographic variation in calls. In the cluttered environments, M. temminckii emitted short downward frequency-modulated calls with short pulse intervals. In the uncluttered environments, M. temminckii emitted long upward frequency-modulated calls with longer intervals and shorter bandwidth. The decreased pulse duration and interval in cluttered environments support the hypothesis that M. temminckii uses the clutter rejection strategy. Additionally, we found that in Brazil, M. temminckii emits shorter calls with higher minimum frequency compared with bats recorded in Venezuela, indicating large-scale geographic variation, probably because of environmental factors.