Parent-Offspring Conflict and the Recruitment of Helpers Among Bee-Eaters

Emlen, S.T. and Wrege, P.H. (1992). Nature (Cover story) 356:331-333.

If helpers have a sufficiently large effect on reproductive success, breeders will enhance their own inclusive fitness more by retaining their offspring as helpers than by allowing them to reproduce on their own. We report here that older male white-fronted bee-eaters (Merops bullockoides ) (typically fathers) actively disrupt the breeding attempts of their sons, and that such harassment frequently leads to the sons joining as helpers at the nest of the harassing father. Calculation of fitness costs and benefits to the various participants helps to clarify both why parents engage in such 'recruitment' behaviour and why sons frequently do not resist.