Reproductive success and nest-site selection in a cooperative breeder: Effect of experience and a direct benefit of helping

We determined whether nest-site characteristics influence reproductive succ ess and whether experience influences nest-site selection in a population o f cooperatively breeding Long-tailed Tits (Aegithalos caudatus). Nest preda tion was high; only 17% of breeding attempts resulted in fledged young. The height of nests was an important determinant of success; low nests were si gnificantly more successful than high nests. A breeder's age, natal nest si te, and breeding experience had no significant effect on nest-site selectio n. However, failed breeders who helped at the successful nests of conspecif ics built subsequent nests lower than nests built prior to their helping ex perience. Failed breeders who did not help showed no reduction in the heigh t of subsequent nests. Moreover, the subsequent reproductive success of fai led breeders who helped was significantly higher than that of failed breede rs who did not help. We conclude that helpers gain information on nest-site quality through their helping experience and thus gain a direct fitness be nefit from their cooperative behavior. We suggest that experience as a help er offers a more reliable cue to nest-site quality than breeding experience because helpers are associated with nests only during the nestling phase w hen few nests are depredated. In contrast, although successful breeders may experience success with a low nest, they are even more likely to have expe rienced the failure of low nests because of the high rate of nest predation .