Fig. 3: Variation in foot use between and within raptors.

a Examples of the three different raptor orders using their feet to manipulate objects. Top row, left to right: Collared Falconet (Microhierax caerulescens), Burrowing Owl (Athene cunicularia), Middle row, left to right: Swallow-tailed Kite (Elanoides forficatus), Fiji Goshawk (Accipiter rufitorques). Bottom row, left to right: Palm-nut Vulture (Gypohierax angolensis), Cinereous Vulture (Aegypius monachus). Photographer credits are listed in Supplementary Table 6. b–d Genus level phylogenies for falcons (b), owls (c) and hawks, eagles and New-World vultures (d) showing the different foot use behavior present for each genus. The key for the skilled foot use matrix is provided in (c), with colored squares reflecting the presence of each of the six behavioral elements. Falcons and owls have similar matrices in which the ability to grasp objects and bring them to the beak is widespread and likely ancestral. In contrast, the ability to bring the foot to the beak while perching (fourth column of the matrix) is only present in five genera of Accipitriformes, but the ability to bring the foot to the beak (sixth column) while flying is more widespread. Also shown is the convergent loss of grasping in New World vultures (in purple) and one of the Old World vulture clades (in green). e Body masses of the three orders of raptors. The color of each dot corresponds to the diet of each species as shown in f. The lower and upper hinges correspond to the first and third quartiles. Whisker extends no further than 1.5 the inter-quartile range, or distance between the first and third quartiles. f Percentage of each diet category in each raptor order. See methods for details on how dietary categories were assigned.