Daniel Russo and colleagues at the University of Bristol said horseshoe bats (Rhinolophidae) find their way in the dark and detect insect prey by emitting long ultrasound calls mainly of a constant frequency. But the researchers have found different rhinolophid species show different frequency values that are distinct enough to allow recognition of conspecifics.

The study proved that in Sardinia, Mediterranean (Rhinolophus euryale) and lesser (R. hipposideros) horseshoe bats show divergence in call frequency, spacing them more than their conspecifics living on the Italian mainland.

The scientists speculate that might be done because of the presence of a third species, the Mehely's horseshoe bat (Rhinolophus mehelyi), practically absent on the mainland but abundant in Sardinia. That bat emits frequencies falling between the other two species, preventing confusion in species recognition.

The research appears in the Journal of Biogeography.