Costs and benefits of female-biased natal philopatry in the common goldeneye. Behav Ecol 12:686–690

Sex-biased natal dispersal in long-lived species may result in interactions between parents and mature young of the philopatric sex. To investigate the evolutionary basis of natal philopatry in a noncooperative species, the common goldeneye Bucephala clangula, we studied possible costs and benefits of simultaneous breeding of females and philopatric daughters. We did not find any fitness consequences of a daughter’s breeding on their mother’s breeding in terms of nest-site selection, body weight, clutch size, hatching date, or hatching success. Our results, therefore, did not support the assumption of the local resource competition hypothesis, that the natally philopatric sex should be more costly to a breeding parent. As possible benefits for daughters returning to their natal area, we tested inheritance of nest sites from mothers and explored whether daughters utilize the presence of their mother by parasitically sneaking into her mother’s nest. Daughters ’ nest-site selection was not associated with the presence of their mothers. A comparison between daughters and control females revealed that daughters chose their nest site closer to their natal nest than expected by nest-site availability alone. Daughters could not expect to inherit a nest site from their mother, and we did not find other indications of cooperation between relatives either. The mother’s clutch size did not increase in the year breeding with the daughter, indicating daughters do not parasitize their mother’s nest. We suggest that benefits such as decreased nest predation risk associated with nesting close to the natal nest site may be important in the natal philopatric behavior of the species. Key words: Bucephala clangula, dispersal, kin competition, local resource competition, natal philopatry. [Behav Ecol 12:686–690 (2001)