Songbird Serenade Is Sneaky Sex Strategy

The babbling of young zebra finches (right and left) may have implications for human baby behavior. CREDIT: Dmitriy Aronov, MIT

Male songbirds woo females much like the way cell phone companies lure customers, a new study finds.

If all cell phone companies offered the same packages, it would be easy to compare rates and choose the best, quickly driving those with costlier plans out of business. Instead, the more expensive providers pitch offerings that are difficult to compare — some promise free calls to friends, others present unlimited evening minutes or free long distance.

Likewise, males songbirds that cannot compete at singing one song will switch to another to try and trick females. The females comparison-shop for mates just as cell phone customers compare plans, researchers found.

"If a male is a better singer than his opponent, he should match the opponent's song type so that it's easy for the female to figure out who's best," said researcher David Logue, a behavioral ecologist at the University of Lethbridge in Canada.

But if a male knows he is beat, "his best bet is to try to fool her by singing something totally different," Logue said. "If she has trouble comparing the two songs, she might make a mistake and pick the worse singer."

In the cases of both the songbirds and the cell phone companies, "the customer or female bird wants to get the best deal, while advertisers want to sell their product or male bird sperm irrespective of whether the customer gets the best deal available or not," said researcher Wolfgang Forstmeier, a behavioral ecologist at the Max Planck Institute for Ornithology in Germany.

This could explain why songbirds evolved to learn how to play a variety of tunes.

"Learning songs gives males options," Forstmeier said. "Males that learn a variety of songs can match lousy opponents' songs, but avoid matching the really great singers."

The same idea might apply to other kinds of animal displays, such as eye-catching dances or bright stripes. Instead of trying and failing to develop into perfectionists, some males become innovators.

"It may be that new signals evolve because they benefit low quality males," Forstmeier said. As long as there is the tendency for female songbirds or cell phone customers to treat bigger or faster or whatever as better, "you kind of can try to sell almost anything as an indicator

To find evidence for this idea, natural choices would be birds often studied regarding songs, such as song sparrows, banded wrens or great tits.

"A good first step would be to ask whether low-quality singers exhibit greater novelty in their songs," Logue said.

Logue and Forstmeier detailed their findings in the July issue of the journal American Naturalist.

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