Date of this Version
Journal of Avian Biology 45: 457–465, 2014
Understanding how organisms adjust breeding dates to exploit resources that aff ect fi tness can provide insights into impacts of climate change on avian demography. For instance, mismatches have been reported in long-distance migrant bird species when environmental cues experienced during spring migration are decoupled from conditions on breeding grounds. Short-distance migrant bird species that store reproductive nutrients prior to breeding may avoid or buff er adverse phenological eff ects. Furthermore, reduced short-term reproductive success could be off set by higher future recruitment of surviving off spring. We evaluated whether recruitment of locally-hatched female off spring was related to hatching date alone or strength of mismatched breeding date for 405 individually-marked adult female common goldeneyes Bucephala clangula (a short-distance migrant) and their ducklings from a site in central Finland where ice-out date has advanced by ~2 weeks over 24 yr. Path analyses revealed that older, early-nesting females with good body condition and larger broods recruited the most female off spring. Off spring recruitment decreased strongly among females that bred late relative to other females in the population each year; the extent of mismatched breeding date, i.e. hatching date scaled to annual ice-out date, was less infl uential. Overall, most females advanced breeding dates when ice-out occurred earlier in spring, but some females exhibited greater fl exibility in response to ice-out conditions than did others. In general, directional selection favoured early breeding over a wide range of ice-out dates. Our results seem most consistent with a hypothesis that some short-distance migrant species like goldeneyes have the capacity to track and respond appropriately to changing environmental conditions prior to onset of breeding.