Mating Rituals: Hammerhead Bats Honk To Woo
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On a river in the African country of Gabon, behavioral ecologist Jack Bradbury went searching for one of the most unusual of animals: the hammerhead bat.
The male is huge — with a 3-foot wingspan, a large head and a bizarre face. This is an animal made to sing: Its larynx takes up more than half its body. That's because the male of the species, Hypsignathus monstrosus, must sing to get sex.
Hammerhead bats, says Bradbury of the Cornell Laboratory of Ornithology in Ithaca, N.Y., are "lekking" species. A lek is a large gathering of male animals intent on mating with females. In Gabon, groups of sometimes as many as 150 males, hang from trees along a river and sing their loud, honking calls. Females fly along the rows of hanging males, eliminating those whose songs aren't appealing.
As a female approaches, the male varies his call, creating a "staccato buzz — a very, very loud, rapid buzzing sound," says Bradbury. Only about 10 to 20 percent of the males get a chance to "buzz," as the females are notoriously picky. They'll narrow the choice down to one lucky bat before mating. When she's done, she pushes off into the air and offers her own post-mating vocalization, a "release sound," says Bradbury.
"Like most lek species, sage grouse for example, it's how you perform a standardized display that often seems to make the difference," he says.
"These are not terribly smart bats. I think most of the synapses in the brain of this male bat [are] devoted to sex, and he doesn't have much else on the mind, except getting some food."
But Bradbury says the male is magnificent looking — enormous eyes, a huge and largely hollow head designed to help the vocalization resonate, and lips that are fluted to further project its song. He may not look like Sinatra, but the results are remarkably similar.
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STEVE INSKEEP, host:
Next, we're going to hear another installment of our series Sounds Wild. The series takes us today to the Africa nation of Gabon, and that's where we'll hear the mating songs of hammerheaded bats. Apparently, a male's ability to sing has a lot to do with his chances of finding a mate since his larynx takes up over half his body. The man listening with us is Jack Bradbury of the Cornell Laboratory of Ornithology.
(Soundbite of hammerhead bat lekking)
Dr. JACK BRADBURY (Behavioral Ecologist, Cornell Laboratory of Ornithology): I'm sitting in the dugout canoe, and you hear in the background the river ibis, which are flying down the river, making their loud noise.
And then a couple of the bats, the males have flown across the river. They're now hanging from the trees by their feet and they're starting to flap their wings fairly feebly and they're starting to warm up their call, this loud metallic honk, honk, honk.
(Soundbite of hammerhead bat lekking)
Dr. BRADBURY: Other males come in and fly up close to a male who's calling, and he then makes that raspy aggressive sound. And occasionally, one will come up and knock the calling guy off his perch and take over his perch.
(Soundbite of hammerhead bat lekking)
Dr. BRADBURY: They've really warmed up now. It's maybe about 6:30, quarter to 7:00. They're all calling at sort of a steady rate and waiting for some females to show up.
(Soundbite of hammerhead bat lekking)
Dr. BRADBURY: Now a female has come to the lek. She flies up and hovers in front of a particular male whose call appealed to her and then he speeds up and he does a staccato buzz.
(Soundbite of hammerhead bat lekking)
Dr. BRADBURY: He pulls his wings in close to his body and makes a very, very loud and very rapid buzzing sound.
(Soundbite of hammerhead bat lekking)
Dr. BRADBURY: Gradually, she whittles her choice down to two or three, and finally she goes back to one and makes him do it several times.
(Soundbite of hammerhead bat lekking)
Dr. BRADBURY: And then she lands next to him, there's silence, they mate - it takes 20, 30 seconds - and then she always gives this call, this eh, eh, eh, release call, which says, I'm through. Let me go. And then she takes off.
(Soundbite of hammerhead bat lekking)
Dr. BRADBURY: The way in which he performs the display, how well he does it, like doing a dance step, how well he does it determines whether the female wants to mate with him.
(Soundbite of hammerhead bat lekking)
INSKEEP: The sounds for our series Sounds Wild come from the Cornell Lab of Ornithology, and NPR's Christopher Joyce helped track them down. To see the hammerheaded bat yourself, visit us at npr.org. Transcript provided by NPR, Copyright National Public Radio.
