The first analysis of ultraviolet (UV) reflections from the mouths of begging baby birds has revealed a remarkable display that birds can see but people can't.
The colors of chick mouths have attracted much scientific interest, says Sarah Hunt of the University of Bristol in England. An old theory held that the bright yellows and reds create conspicuous targets for parents delivering food in dim nests. Newer evidence shows that health influences mouth color, which suggests that various shades give parents a quick clue to a chick's condition and need for food.
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