Behavioral Ecology Helpers at the Nest One form of kin altruism in birds is "helpers at the nest." Primary helpers are immediately accepted by a breeding pair, invest as much work as the breeders, and are usually a son of that breeding pair born the previous year. These sons do not mate with females that year. Secondary helpers are accepted into the nest after the eggs have hatched. These helpers are unrelated to the breeding pair, and often do not work nearly as hard as the breeders. If the male breeder should die, the secondary helper will often become the mate of the widow. 90% of birds are monogamous, and so like the human dating scene, most of the good ones are already taken. Helping at the nest allows the male the opportunity to mate the female if her mate dies. Females of some species may remain with their parents for a year and help with the next brood. These females receive an indirect benefit by increasing the survival of siblings, but they also tend to have a higher direct fitness when they do breed than individuals who did not help at the nest.
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