During their song and dance displays, male superb lyrebirds (Menura novaehollandiae) create an elaborate acoustic illusion of a mixed-species flock of birds, according to new research.
A male superb lyrebird (Menura novaehollandiae). Image credit: Alex Maisey, University of Wollongong.
The superb lyrebird is a large, pheasant-sized species of passerine bird native to Australia.
Male superb lyrebirds display their tail feathers and mimic other birds’ calls during courtship dances. These displays take place on low mounds of leaf litter, which the male creates around his territory.
They are also world famous for their extraordinary ability to mimic complex sounds of human origin such as chainsaws. But the reasons for their impressive mimicking skills have been somewhat mysterious.
“Wild male superb lyrebirds have two main types of mimicry,” said co-author Professor Robert Magrath, a researcher in the Research School of Biology at the Australian National University.
“They are famous for mimicking the songs of other birds, delivered loudly in breathtaking recitals.”
“But we found they use a different type of mimicry at their display mounds, where females visit for sex.”
“They use this mimicry when a female tries to leave without mating, and during the act itself — to create the illusion of a nearby threat.”
“This suggests it’s a deceptive part of male lyrebirds’ sexual strategy,” said lead author Dr. Anastasia Dalziell, a researcher at the Cornell Lab of Ornithology, the Research School of Biology at the Australian National University, the Hawkesbury Institute for the Environment at the Western Sydney University, and the Centre for Sustainable Ecosystem Solutions at the University of Wollongong.
“They mimic what’s known as mobbing — a common anti-predator ploy. It involves a loud alarm call to attract other birds to harass a predator, eventually forming a noisy flock.”
“The male lyrebirds not only imitate the alarm calls of several species of songbird, they pattern the calls to create the illusion of many birds calling at the same time, even including the sound of wingbeats. It’s a very convincing illusion — so convincing it fools other birds into responding.”
This mimicry has the characteristics of a ‘sensory trap’ — with the male attempting to trick the female into responding as though there’s a predator threat.
“Mimicking when the female attempts to leave may be a bit like saying ‘it’s dangerous outside, stay,’ while mimicking during copulation could extend the duration, like saying ‘freeze,’ making sure the sperm is transferred,” Dr. Dalziell said.
“At first it seemed absurd, but we quickly realized that mimicking a mobbing flock during copulation was the norm for male lyrebirds. It happened during an every single copulation we filmed.”
“The more we researched it the more remarkable this behavior became. Copulation calls are not common among song birds, and song birds very rarely copulate for longer than two seconds. The lyrebirds in our study averaged 45 seconds.”
The findings appear in the journal Current Biology.
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Anastasia H. Dalziell et al. Male lyrebirds create a complex acoustic illusion of a mobbing flock during courtship and copulation. Current Biology, published online February 25, 2021; doi: 10.1016/j.cub.2021.02.003
