Bird Sex Round-up: Why Monogamous Birds Cooperate, Why Finches Cheat

Bird cheaters beware: They're watching you. Two recently published studies, one in Science and one in Nature, have asked what bird benefits come from remaining faithful--or cheating on the down-low. Don't Cheat Analyzing the breeding habits of 267 bird species, two researchers have found that it may pay for some birds to stay true to their partners. Cooperative breeders--birds that help raise each others' young--appear to be more monogamous. Researchers looked at the number of broods with a half brother or sister, the products of a mother bird's free-loving ways. Cooperative birds' cheating rate averaged around 12 percent, while noncooperative birds around 23 percent. Also, the most promiscuous cooperative birds appeared to receive less help from other birds in the nest. These findings support the theories of evolutionary biologist Jacobus Boomsma (who wasn't involved in this study), who has tried to explain the puzzle of cooperative behavior that doesn't directly ...