Figure 2.

Diet trajectories for individual breeding male goshawks (a) (individuals that bred for at least 2 years; data points joined for samples of 2 years, and linear regressions fitted for samples of 3 or more years); (b) correlation between diet composition of first-time breeding males (proportion of feral pigeons in diet of first breeding attempt) and longevity (number of years recorded breeding). Panel (a) suggests improvement of individual foraging competence (increases shown in black, decreases in grey), but on the basis of (b), population-level changes in phenotype frequencies cannot be ruled out.