Tbe use of conspecific reproductive success for breeding habitat selectionin a non-colonial, hole-nesting species, the collared flycatcher

1. Breeding habitat quality strongly affects fitness. Therefore, individual s are likely to select their breeding habitat after gathering information o n quality of potential breeding patches. In the study reported in this pape r, we investigated whether local reproductive success of conspecifics in a patch (patch reproductive success, PRS) could be used to assess habitat qua lity and make dispersal decisions in a non colonial, hole-nesting, passerin e bird, the collared flycatcher (Ficedula albicollis). 2. Assumptions for such a breeding habitat selection mechanism were met: th e habitat patches were of different quality, as measured by PRS, with relat ive quality varying between years, and PRS was autocorrelated in time. 3. As in many other species, breeding dispersal was related in both sexes t o individual reproductive success before dispersal: unsuccessful individual s were more likely to disperse than successful ones. 4. Additively, PRS influenced both breeding and natal dispersal. This effec t depended on sex. Dispersal was negatively related to PRS in females, and positively in males with low competitive ability (juvenile and unsuccessful adult males). 5. Breeding dispersal was positively related to flycatcher density in males , but negatively in females. Moreover, when included in the analyses, layin g date of the previous breeding attempt (which should be correlated with co mpetitive ability) replaced the effect of PRS in adult males. 6. The observed patterns can be explained by PRS (or another variable corre lated with PRS) being used to assess different components of habitat qualit y in each sex, in relation to intraspecific competition pressure. We sugges t that males of low competitive ability may either use PRS to assess the le vel of expected intraspecific competition the following year, and choose to disperse from high PRS woodlands, or be forced to disperse when PRS is hig h because of strong competition. Females might use PRS to assess the expect ed reproductive output if breeding in the patch the following year.