Inside Report (2)

And you think shoppers rummaging at the fruit counter are picky!

University of Wisconsin zoologist Timothy Moermond is more convinced than ever that birds are no featherheads. For two years he and his wife observed fruit-eating birds in Costa Rica. The birds appeared to weigh the quality of the fruit and the effort and distance involved when deciding on a meal. The two then conducted experiments of their own and pronounced the birds' decisionmaking process rational, fine-scaled, and consistent. Ornithologists generally agree bird behavior is intelligent. But the question of whether birds make ''rational'' choices, generally regarded as a human characteristic, is considerably more controversial.

The findings may add weight to one mom's advice: Don't toss out fruit with peck marks in it, kids - it'll be the sweetest, because birds always pick the sweetest fruit.