Finches flirt unwisely if they can only use their left eyes

A patch over a male Gouldian finch’s right eye works like beer goggles, though the bird doesn’t need booze to flirt unwisely. If limited to using his left eye when checking out possible mates, he risks making really stupid choices.

Gouldian finches have caps of black, red or yellow feathers on their heads. In nature, the birds prefer to mate with partners with the same cap color. Yet black-headed males rendered temporarily left-eyed by a tiny removable eye patch flirted as readily with red-heads as with black-heads, says cognitive ecologist Jennifer Templeton of Knox College in Galesburg, Ill. That’s not smart because daughters typically fail to survive when Gouldian finches mate outside their cap color.

Also the male himself “becomes less attractive,” Templeton says. When the bird’s right eye was covered, he sang, bowed and posed less during his attempts at courtship. Some left-eyed males didn’t manage to make up their minds at all, but “just hopped around randomly,” Templeton says.

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