New Holland honeyeaters are experts at sounding the alarm when there’s danger,according to new research from biologists at The Australian NationalUniversity (ANU) and the University of Cambridge.
Study authors, Dr Jessica McLachlan and Professor Rob Magrath, foundhoneyeaters can spread the word in the blink of an eye, using a two-stagealarm.
It’s particularly effective when they are threatened by fast-moving birds ofprey.
“When a hawk is swooping down, its target has only a fraction of a second toflee to cover – a split second can make the difference between life anddeath,” Dr McLachlan said.
“But animals often signal urgent danger using repeated notes, which makes sureothers hear the warning but it takes a long time to deliver.
“So there’s a problem. How to send a lightning-fast message in a long call?”
New Holland honeyeaters solve this problem elegantly. They ‘front-load’information about urgency into the first note of their alarm call, so otherhoneyeaters can respond quickly.
The clever honeyeaters follow this up with more notes to reinforce the messageand signal how long to remain hidden.
“They use a long call, with lots of notes, to make sure the message is heard,”Professor Magrath said. “And the more notes, the more urgent the danger.
“But they also modify the first note to indicate if it’s necessary to takeimmediate cover. So it’s a two-part message that is quick, reliable andinformative.”
The technique is so effective the authors expect to see other species adoptit.
“Many other species modify alarm calls as the threat increases, but there issurprisingly little known about how fast they convey the message,” ProfessorMagrath said.
The researchers conducted their study in Canberra’s Australian NationalBotanic Gardens over a period of several years.
“These birds live in the Gardens and are used to having people around. Thishelped us to record natural interactions with their predators, such assparrowhawks and currawongs, and to video the honeyeaters’ responses todifferent alarm calls,” Professor Magrath said.
The research is published in the journal Proceedings of the Royal Society B.
Image credit Jessica McLachlan
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