Male birds in the throes of sexual unity will mimic the sound of a troubled crowd of other birds to fool their mate and keep them from escaping, new research from Australia finds.
The remarkable discovery was made after audio and video analysis of beautiful lyrebirds – a species known for extravagant dance routines and the ability to mimic the call of over 20 other species.
Researchers found that males could simultaneously reproduce both the vocal “mobbing” sounds and the wing-beat sounds of other bird species when trying to scare off a predator.
The mimicry of male lyrebirds is so accurate that it not only fools the female lyrebird, but playback experiments also showed other small birds were tricked into thinking there was a threat nearby.
Captive lyrebirds are known to imitate other sounds, including chainsaws and car alarms.
Dr Anastasia Dalziell, a behavioral ecologist at the University of Wollongong, led the research published in the journal Current Biology.
Male lyrebirds are capable of amazing and horrible things, she said.
Dalziell first heard lyrebirds mimic the bullying in 2007 and went on to study the skill in two populations: one in Sherbrooke Forest in Victoria, the other in the Blue Mountains in New South Wales. These locations are 700 km apart.
She and her colleagues were sure that the mimicry had something to do with mating, but she didn’t immediately know why.
But other scientists pointed to similar behavior in other animals. Male topi antelopes use a false alarm call when females move away from their “exhibition arenas.”
The male corn boron moth will mimic the sound of predatory bats long enough for a female to freeze, giving the male time to mate.
Lyrebirds use the same strategy, but do it in a really over-the-top way, as lyrebirds seem to be doing, Dalziell said.
The study found that male lyrebirds only reproduced the sound when they had attracted a female to their “display area” – a small space in the forest cleared for courtship – or when they were copulating.
These two moments, Dalziell says, are crucial to reproductive success “suggesting that mimic bullying is a crucial sexual behavior for men.”
She said they were further convinced when their camera images showed female lyrebirds responding to the mimic calls and returning to exhibition areas.
When the mimic calls were analyzed in detail, researchers were able to detect mobbing calls that sounded like eastern yellow robin, brown thorn birds, and white eyebrow worms. Occasionally, the researchers discovered alarm calls that sounded like two types of possums.
To compare the mock mobbing chorus to a real one, Dalzielle said they had to employ their own deceptive behavior to get local birds to reproduce the calls.
“We threw in a rubber hose,” she said.
The male lyrebirds always used their deceitful trick when females tried to escape while mating, Dalziell said.
“The males pull out all the stops to allow the female to mate. It’s just one of the many things men do.
“They have a beautiful dance routine and they sing from sunrise to sunset and so the female gets all those other beautiful signals. We shouldn’t see the lyrebirds as terrible.
‘We tend to be romantic about the lyrebird, but they are animals and can do amazing things. But they also do things we don’t like or find disturbing and problematic, just like people. “
Lyrebirds will routinely mimic other species, and Dalziell said their repertoire spans more than 20 different species.
“They only mimic local species. They mainly do it in the breeding season, and it’s part of their morning chorus – and it’s very, very accurate. “