Trade-off between mating opportunities and parental care: brood desertion by female Kentish plovers

Why do some parents care for their young whereas others divorce from their mate and abandon their offspring? This decision is governed by the trade-of f between the value of the current breeding event and future breeding prosp ects. In the precocial Kentish plover Charadrius alexandrinus females frequ ently, but not always, abandon their broods to be oared for by their mate, and seek new breeding partners within the same season. We have shown previo usly that females' remating opportunities decline with date in the season, so brood desertion should be particularly favourable for early breeding fem ales. However, the benefits are tempered by the fact that single-parent fam ilies have lower survival expectancies than those where the female remains to help the male care for the young. We therefore tested the prediction tha t increasing the value of the current brood ibv brood-size manipulation! sh ould increase the duration of female care early in the season, but that in late breeders, with reduced remating opportunities, desertion and thus the duration of female care should be independent of current brood size. These predictions were fulfilled, indicating that seasonally modulated trade-offs between current brood value and remating opportunities can be important in the desertion decisions of species with flexible patterns of parental care .