How birds time their breeding
Dr Eleanor Cole
How birds time their breeding to maximize food availability for their r
In seasonal environments, the breeding success of songbirds such as the great tit depends strongly on when in the spring they begin laying their clutch. Great tits primarily rear their chicks on larvae of the winter moth, which in turn feed on the emergent leaves of oak trees. Timing is essential in this system: oak budburst will largely depend on spring temperature, and winter moth caterpillars will hatch out in synchrony with oak budburst so that they can feed on the newly emerged leaves. These caterpillars rapidly pupate and then become inaccessible to birds, resulting in a very short food peak for breeding great tits. From the birds’ perspective, food demand is highest when chicks are about a week old, and therefore in order to time their breeding well, females must begin laying their clutch around a month before the anticipated food peak. How birds are able to predict and track this peak has been the subject of much research, some of which has been carried out at Wytham Woods near Oxford. This talk will present some of this work, exploring how Wytham’s tits have tracked climate change over the last 50 years, what cues they may be using to do this, and how these questions can be studied using satellite imagery.