Figure 4From: Reproductive responses of birds to experimental food supplementation: a meta-analysisEffects of timing and food accessibility on variation in breeding success. Effect of (a) timing of food supplementation and (b) level of accessibility to the feed on breeding success variation in response to food supplementation in birds. Mean effect sizes (Hedges d) and 95% confidence intervals are presented, with sample size (number of experiments) above bars.Back to article page