1. In birds, early breeding individuals generally reproduce more successfully than late breeding individuals. The lack of response to this selection could be explained by resource constraints during the egg production period. 2. Parus species can learn from the mismatch experienced between breeding time and nestling food availability and subsequently adjust their breeding time accordingly. In two Great Tit populations, breeding time was manipulated by creating an artificial food peak. This allowed us to study fitness consequences of manipulated breeding time in the following year without the confounding effects of food supplementation. 3. In one population, manipulated females advanced their laying dates in response to the artificial food peak. However, sample sizes were too low to quantify fitness consequences. In the other population, no response to the treatment was found. This difference could be caused by differences in resource availability in early spring between the two habitats. Low resource availability in early spring could also explain the lack of response to selection observed in one population [KEYWORDS: Climate change ; food supplementation ; Parus major ; resource constraints ; selection on breeding time]
Original languageEnglish
JournalFunctional Ecology
Journal publication date2006

ID: 240208