Study Site
The experiment took place at Silwood Park, Imperial College London (51°24'30.6"N 0°38'31.3"W) in a 200m x 350m stretch of mixed deciduous woodland which borders open grassland (Fig. \ref{621552}). An experiment focusing on the breeding ecology of blue tits was also being conducted in the woodland using artificial nesting boxes and marked trees. No trees were shared between the two experiments, and a minimum of 10m from each marked tree was maintained to avoid bias.