Male lyrebirds deceive females into mating by creating mobbing flock sound
Male lyrebirds will mimic the sound of mobbing birds to fool female lyrebirds into mating with them, scientists have discovered.
Initially, the scientists were studying the male’s familiar mimetic song, when they came across a different type of mimicking never heard before.
“It’s much softer and given only during dances and when courting females,” Behavioural ecologist and co-author of the paper Rob Magrath says. “The calls are harsh and buzzy; anything but beautiful to the human ear.”
While the reproductive benefits remain a mystery, the timing of the calling suggests males are attempting to deceive females to increase the chance of reproductive success.
“Usually a chorus of mobbing calls means that there is a predator nearby,” Rob says. “If females are fooled by the male’s mimicry, she may be more likely to stay with the male, rather than wandering off, perhaps towards unseen danger. So males may be more successful getting matings if they can get females to stay longer.”
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And of course, the mimicry is close to flawless. “They mimic the calls of several species, and mimic several individuals of the same and different species calling together.
“They even mimic the sound of wingbeats, given when birds fly around and harass the predator. The end result is that they mimic a whole acoustic scene, as if conjuring a mobbing flock from thin air.”
The finding isn’t so far-fetched considering deception is a well-worn reproductive strategy in the wild. “Male topi (antelope) give false alarm snorts if a female starts to wander off his territory during the mating season,” Rob says. “This deceives the females into remaining with the male and other females, giving males further opportunities for mating.
“There are other possibilities, but at the moment it seems that deception is the most likely explanation.”
While it’s well-known that lyrebirds are talented mimics, conjuring the illusion of an entire flock of mobbing birds is “unprecedented” Rob says.
“The male lyrebird is like a composer who both conducts an orchestra and plays all the instruments. The imitations of calls are extremely accurate, just like the originals. The calls of different species are run together, and birds may deliver some calls loudly and some softly, mimicking birds calling at different distances. The sound of flying wings adds to the acoustic scene.”
The next step for research is testing females directly to see how they respond to the mimetic illusion of mobbing flocks.
The findings will also have an impact on our understanding of sexual preference in birds, which was thought to be determined by the quality and beauty of an individual bird’s song. “Our work suggests that complex song could also arise through sexual conflict and deception, not appraisal of quality or beauty by females,” Rob says. “It will be interesting to see if this possibility applies to other species.”