Noisy males may have learned a benefit of deception
Even with no female in sight, peacocks sometimes give the distinctive copulation call they hoot during the final rush toward a female.
A male’s solo shriek may be a bit of stagey deception that attracts distant females to check him out, says Roslyn Dakin of the University of British Columbia in Vancouver.
Animals that whoop and crow when mating intrigue biologists with the possibility that loud noises offer some benefit, such as advertising fertility, social rank or just success in courtship.
In Dakin’s observations of birds during breeding season, calls did bring a modest increase in female company, she reports. And faking the sex calls could be a trick that requires learning, she and Robert Montgomerie of Queen’s University in Kingston, Canada, suggest in the April American Naturalist.
Dakin describes the sound as “an exuberant squeal or hoot.” It’s one of several calls that male peafowl make but females don’t. A peacock typically hoots when he finishes displaying his feathery splendor to a female and rushes forward to try for full contact. (In 77 percent of hoot-rushes Dakin saw, the female dodged away.)
Dakin tallied 432 hoots over four breeding seasons while watching free-roaming peafowl Pavo cristatus at two zoos and the Los Angeles Arboretum. About a third of the hoots came from males with no female nearby and, in most cases, none even in sight.
After sounding off, a male was about 14 percent more likely to have a female visitor than he was before, Dakin says. And when Dakin broadcast recorded hoots (three spaced over an hour) on a breeding ground, a female was 9 percent more likely to arrive shortly afterward.
Another peacock researcher also argues that hoot calls attract females. Jessica Yorzinski of Purdue University in West Lafayette, Ind., and a colleague reported this finding in Behaviour in 2013 after playing the calls (more frequently than Dakin did) to wild birds in India and captives at Duke University. And she frequently heard hooting from the North Carolina peacocks with no females around. It certainly seems plausible, she says, that solo hoots lead a female to think a male is more popular than he is.
Nonhuman animals do lie. Male topi antelopes prolong the visits of fertile females by giving unwarranted snorts of alarm as if a lion lurks nearby (SN:6/19/10, p. 14). And birds called fork-tailed drongos give false alarms that send other birds or meerkats scooting for cover, abandoning a lunch that the drongo can then steal.
If the solo peacock hoots are deceptive, something must be keeping them rare, Dakin says. Scams that get too common cease to fool. Among the 39 males she monitored, 15 never gave a hoot without female company nearby. As to why, she says, “my best guess is that the deceptive behavior in this case is acquired through learning.” And some males just never learn.
WHO HOOTED A peacock gives his distinctive hoot as he rushes to try to mate (first unsuccessfully, then successfully) or when he's alone. That solo hoot may draw female visitors as if he's a popular bird that’s attracting more attention than he really is.
Credit: Attempt hoot video by R. Dakin; solo hoot video by Kathy Kerran; adapted by Ashley Yeager
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