Male lyrebirds use clever mimicry to increase their chances of sexual success, according to a new study involvingย researchers fromย The Australian National University (ANU).ย ย
Lyrebirds are famous for their ability to mimic complex sounds of other species, including โhumanโ sounds like chainsaws. Now biologists think theyโve discovered what drives this skill.
According to study co-author, ANU Professor Robert Magrath, wild males have two main types of mimicry.
โThey are famous for mimicking the songs of other birds, delivered loudly in breathtaking recitals,โย Professorย Magrath said.ย โBut we found they useย a different type of mimicry at their display mounds, where females visit for sex.
“They use this mimicryย when aย femaleย tries to leave without mating, and during the act itselfย โ to create the illusion of aย nearbyย threat.โ
Lead author Dr Anastasia Dalziell, a Visiting Fellow at ANU, says this suggests itโs a deceptive part of male lyrebirdsโ sexual strategy.
โThey mimic whatโs 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,โ Dr Dalziell said.
โThe 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. Itโs a very convincing illusion โ so convincing it fools other birds into responding.โ
Thisย mimicry has the characteristics ofย aย โsensory trapโย โ with the male attempting to trick the female into responding as though thereโs aย predatorย threat.
โMimicking when the femaleย attemptsย to leave may be a bit like sayingย ‘itโs dangerous outside, stay’, while mimicking duringย copulationย couldย extend the duration,ย like saying ‘freeze’,ย making sure the sperm is transferred,โย Drย Dalziellย said.
Theย findingsย wereย a surprise toย the research team.
โAt first it seemed absurd, but we quickly realised that mimicking a mobbing flock during copulation was the norm for male lyrebirds. It happened during every single copulation we filmed,โ Dr Dalziell said.
โThe more we researched it the more remarkable this behaviour 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.โ
Dr Dalziell is currently a postdoctoral Research Fellow at Wollongong University, as well as a Visiting Fellow at the University of Western Sydney and Cornell University in the US.
The teamย now hopeย to delve further into how theย female lyrebirds respond to both real and mimicked mobbing flocks.ย Their workย has been published in the journalย Current Biology.
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