Wily lyrebirds

Males are prone to try anything to get lucky, and lyrebirds seem to have it clinched, according to study published in the journal Current Biology.

Scientists have made a surprise discovery that the wily songbirds use their extraordinary skills to mimic a nearby threat and trick females into hanging around for sex. 

They’ve also raised the bar on mimicry, it seems, as their calls not only imitate individual alarm calls but an entire scene of warning calls from a mobbing flock with multiple bird species – even including fluttering wing sounds.

Mobbing is a common ploy birds use when predators are around, calling others to create a noisy flock and harass the unwelcome intruder.

It appears the lyrebirds imitate the threat when females try to leave their display mound without mating, and even during the act. It seems to work – they copulate for around 45 seconds compared to other songbirds who are typically done and dusted in less than two.

The researchers discovered this phenomenon during a field-based study of the superb lyrebird (Menura novaehollandiae). 

“I was expecting to focus solely on the fabulous, lyrical mimetic song that male lyrebirds are most well-known for,” says lead author Anastasia Dalziell from Cornell University, US, a visiting fellow at Australian National University. 

“But as I followed lyrebirds around, recording their dawn song and morning activities, it soon became clear that males occasionally would produce a completely different kind of mimicry … [that] sounded like a mixed-species mobbing flock.”

The team ran a couple of experiments to confirm that the males mimic the cacophony generated by a mobbing flock and to investigate why they would do such a thing. 

First they compared the acoustic properties of the suspected mimicry and the sounds of real flocks. The latter they generated using models of predators (a rubber red-bellied black snake and a taxidermied boobook owl), and they followed adult male lyrebirds around Sherbrooke Forest, Victoria, with hand-held recorders to capture them imitating the sounds.

Playing the recordings to other bird species showed they reacted similarly to speakers broadcasting a male lyrebird mimicking the flocks as to the real flock sounds.

Further observations revealed the lyrebirds never did the mimicry when a real predator was around, according to Dalziell. But they always produced the noise when a visiting female tried to leave without copulating (perhaps saying “it’s dangerous outside, stay”) and while mating (possibly to make sure the sperm is transferred), confirming their trickery.

“Our results conflict with the widely accepted theory that birdsong is an honest signal of quality,” says Dalziell. 

“Instead, our study suggests that the elaboration of ‘song’ can be driven by sexual conflict and deception, which represents an important departure from conventional explanations for song evolution that rely on females’ preferences for male extravagance.”

It’s the most “complex copulation vocalisation yet described,” she adds, showing the birds can continue to inspire awe. “Even well-known Australian animals still have major surprises in store!”