Fig. 2. Schematic representation of a detour trial indicating a typical forest edge configuration. The triangle indicates the location of the speaker and circles indicate the locations of focal birds (#1 and 2) at first sight. For each focal bird, we recorded the initial shortest distance that the bird would have to travel in the open to reach the speaker (DO_i), the distance of the route available under forest cover, and the number of conspecifics present. Actual paths taken by birds were recorded as the sum of segments in the open (DO_a) and under forest cover (DF_a). Note that trials were conducted in both u-shaped (e.g., Bird #1) and v-shaped (Bird #2) situations. Dependent variables included the proportion of the actual path that occurred in the open (Epsilon DO_a / (Epsilon DO_a + Epsilon DF_a)), the risk area defined between the bird's path and adjacent forest, and the forest edge distances (FED) describing the maximum distances from forest edges that a chickadee ventured during a given shortcut.