Media & Education
BATS Magazine

Volume 34, Issue 3, Summer 2015

On the Dating Scene

The lesser short-tailed bat’s take on lek breeding


New Zealand’s lesser short-tailed bat (Mystacina tuberculata) is unusual in more ways than one. Omnivorous and opportunistic, these bats forage on the forest floor when searching the night sky yields little food. With a majority of their weight in their wrists, they can comb through deep leaf litter and munch on all the critters they find.

New Zealand Bat

But the temperate bat’s un-bat-like behavior extends beyond its dietary habits. When it comes to the mating game, the furry creature has adopted new rules by which to play.

It starts with a song. Tucked away in the cavity of a hollow tree, the male lesser short-tailed bat is known to vocalize for hours in pursuit of a female. Singing from the roost, however, is not where the anomaly lies; many other species of bat are known to carry a tune. What is unusual, albeit fairly straightforward, is what happens next: In response to the males’ vocalizations, the female lesser short-tailed bats act as promiscuous independents as they seek out males on display—without concern for any direct gains those males might provide as a result of a sexual encounter. In scientific terms, the lesser short-tailed bat practices what researcher Cory Toth refers to as “lek breeding.”

Camera on Bat Roost

“Lek breeding is a system where females receive no resources from the males,” he says. “They're just selecting males based on the quality of their displays and so it's basically a distilled version of sexual selection.”

With funding from BCI, Toth managed to keep track of the lesser short-tailed bat’s mating patterns using microchip technology and infrared cameras. In doing so, he realized the bat’s “weird mating system” was indeed consistent with the defined characteristics of lek breeding.

Bat Roost

To this day, lek breeding remains one of the most confounding mating systems among mammals. Leks are presumed to form in part for economic reasons. Frugal males who are at a loss trying to protect their resources or defend a mate ultimately decide to advertise only for one-night stands. For the male lesser short-tailed bat, self-advertisement—in the form of sexual display and singing - occurs in small holes found in trees. It is presumed that males sing from the cavities in order to attract potential lovers. Much to Toth’s surprise, the male bats also divvy up the “singing duties,” with multiple males sharing a single cavity on a one-at-a-time basis.

Toth’s discovery is not all it seems, however. According to his research,  a major “side effect” to lek breeding is that the lesser short-tailed bat can only survive in undamaged tracts of native forest. As New Zealand forests become more and more fragmented, the remaining populations of lesser-short tailed bats decline by extension.

And just as a performer needs a stage, the male bat needs that forest. Not just for eating or sleeping. But also for singing. 

 

High Skies to the Forest Floor

Portrait of Bat Roost

The lesser short-tailed bat is a very unusual and unique creature. While most bats find their meals in the sky, this particular bat has no problem eating dinner off the forest floor.

The lesser short-tailed bat’s ability to forage on the ground can be accredited to its body composition. Though measuring only 75 mm in length, these small creatures have the ability to fold their wings under a leather-like membrane. This membrane runs along the side of the body, and allows them to use their forearms as front legs. And just like their shrew ancestors, these terrestrial bats have become experts at using those forearms to burrow through forest debris.

Though a typical bat might be confined to eating mosquitos, moths, and beetles, the lesser short-tailed bat is far from a picky eater. Worms, crickets, fruit, and even nectar are staples in their diet. In this regard, these bats also act like bees, pollinating flower after flower as they feast.

 
 

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