The intricate signals emitted by the male New Zealand lesser short-tailed bat Mystacina tuberculate have been found to allow females to judge its suitability as a mate.
The study found that bats rarely fell silent during the six-hour period they spent in the roosts and the researchers calculated that a male could produce up to a 100,000 syllables (a syllable is a discrete vocalisation, separated from another syllable by silence) in one night.
“Lesser short-tailed bats potentially have one of the highest sustained song outputs for either birds or bats that researchers know of,” says lead author Dr Cory Toth, from the University of Auckland.
Four distinct notes were identified in the males’ vocalisations: upsweeps, downsweeps, trills and tones. These were articulated as single notes or combined into one of 51 syllables.
Four syllables were particularly prevalent and were produced uniquely by each bat. The length of the second most popular syllable, the trill-downsweep combination, is believed to hold precise indications of the size of the singer, allowing the female to size up her suitors through auditory signals alone.
“Our results suggest the singing displays of male lesser short-tailed bats are signals that provide useful, honest cues of male characteristics and identity to females, and are as complex as the songs of many bird species,” explains Professor Stuart Parsons of the Queensland University of Technology.
The New Zealand lesser short-tailed bat (pekapeka-tou-poto in Māori) is endemic to the country, and is the only species in the Mystacinidae family. It is notable for foraging on the forest floor more than any other bat species.
The species is listed as Vulnerable on the IUCN Red List due to forest clearance, predation from introduced stoats and rats, and consumption of poisoned bait set out for invasive species.