Reproductive investment and moult-breeding overlap in the collared flycatcher Ficedula albicollis: an experimental approach

We manipulated brood sizes of 132 pairs of the collared flycatcher to investigate whether or not an investment in reproduction was traded against an investment and timing of the post-nuptial moult. Our manipulations did not affect the probability of moult-breeding overlap in males, and there was no effect on their moult scores at fledging time of the young. Males and young birds initiated moult earlier than females and old birds, respectively. Very few females started moulting during the period of nestling care. Reproductive success in terms of recruitment rate of fledglings was independent of parental moult stage during reproduction, which indicates that the manipulation did not induce a trade-off between moult and post-fledging care. Furthermore, the survival probability of adults was independent of brood size manipulations and their moult stage at fledging time. Thus, our brood size manipulations showed no evidence for a trade-off between reproductive and moult investments in the collared flycatcher.

Hemborg, C. & Merila, J. 1999, Ann. Zool. Fennici 36: 1-9