Darwin noticed that some monogamous birds have very colorful males: mallards, for example, and blackbirds. He suggested that it would still benefit males to be seductive and so win the first females that are ready to breed, if not the most, and his conjecture has largely been borne out by recent studies. Early-nesting females rear more young than late-nesting ones, and the most vigorous songster or gaudiest dandy tends to catch the early female. In those monogamous species in which both males and females are colorful (such as parrots, puffins, and peewits) there seems to be a sort of mutual
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