Birds eavesdrop on songs to find the best breeding spots

Washington, June 19 : While human beings thumb through real estate listings and drive around neighbourhoods to find the best place to live and raise a family, some birds have an easy way out - they just listen to songs.

A study, conducted by researchers from Oregon State University, Wellesley College, Queen's University and Trent University in Ontario, Canada, showed that some migratory songbirds figure out the best place to live by eavesdropping on the singing of others that have successfully had baby birds.

It is such a strong communication and behavioural trait that researchers playing recorded songs induced some birds to nest in places they otherwise would have avoided.

This suggests that songbirds have more complex communication abilities than had previously been understood, and that these 'social cues' can be as or more important than the physical environment of a site.

"Finding the right habitat in which to breed is a matter of life and death for most birds. They don't live a long time and they need to get it right the first time," said Matthew Betts, an OSU assistant professor of forest science and expert on avian ecology.

"The common wisdom is that these birds select sites solely on vegetation structure. If a bird selects a site for its nest that doesn't have the appropriate cover and food supply, it most likely won't be able to successfully breed. But now we know that young birds can listen to the songs of more experienced and successful birds and use this to help decide where they will nest the next year," Betts said.

The researchers found this in experimental studies at 54 research sites with the black-throated blue warbler in the White Mountains of New Hampshire.

During the fall when some of these birds had successfully mated and were singing to their young - probably to teach the young ones how to sing - the researchers played recordings of their song in other places that were, in fact, lousy bird habitat.

Other black-throated blue warblers flying overhead heard these songs and decided it must be a good place to live, all visual evidence to the contrary, and returned to these exact sites the next spring to nest.

The study showed that male birds were four times more likely to follow the cues provided by song than by their own observations of the physical environment.

And even though the male had made a poor choice, the females - too trusting for their own good - followed them there.

"We had a lot of birds come to settle in inappropriate habitat, just because they had heard our recorded bird songs there the previous year. We were actually pretty surprised that the effect of this communication was so strong," Betts said.

Betts said that the study was done with a single species of songbird but its findings are probably relevant to at least some other songbirds and perhaps other animal species as well.

The study was published in a professional journal, Proceedings of the Royal Society B.

ANI