Tiny Birds Mimic 'Hawk Call' of Other Species to Avoid Predators

It turns out that tiny birds may be able to warn others of an approaching predator in order to avoid being preyed upon themselves. Thornbills mimic the warning call of local species to create the impression of an impending hawk attack in order to distract other birds from raiding their nests.

Currawongs raid the nests and hunt the chicks of thornbills. However, they're also prey to goshawks. Although currawongs normally benefit from listening in on hawk alarm calls of other species, this can work against them.

Thornbills mimic the calls of local species to create the impression of an impending hawk attack. This distracts the currawong and provides the thornbill nestlings with an opportunity to escape.

"The enormous size difference between a tiny thornbill and a .5 kg goshawk might make it difficult for thornbills to mimic hawk vocalizations accurately, limiting them to mimicking the chorus of hawk alarm calls given by small local species instead," said Jessica McLachlan, one of the researchers, in a news release. "As hawks are silent when hunting, the alarm calls of local species may be the only sound that warns of a hawk's presence."

When their nests are under attack, thornbills used their own and mimicked hawk alarm calls. This caused Currawongs to delay their attacks for twice as long.

"Distracting a currawong attacking the nest could give older thornbill nestlings a chance to escape and hide in the surrounding vegetation," said Branislav Igic, the leader of the new study. "It's perhaps the thornbills best defense in this circumstance because physical attacks on the much larger currawong are hopless."

The findings are published in the journal Proceedings of the Royal Society B.

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