CRANIAL FUNCTIONAL MORPHOLOGY AND ITS RELATIONSHIP WITH THE FEEDING ECOLOGY OF DIURNALS

BIONDI, LAURA, MARÍA SUSANA BÓ AND ALDO VASSALLO

Puerto Iguazú, Argentina

Conferencia; II Neotropical Raptor Conference; 2006

Neotropical Raptor Network

The relationship between feeding ecology and cranial functional morphology in diurnal raptors (Cathartidae, Falconidae and Accipitridae) was analyzed. Species were classified according to their diets as generalists (G), mammal-specialists (MS), bird-specialists (BS), or carrion-eaters (C). Based on linear and angular cranial measurements, we constructed indices that reflect functional aspects such as the mechanical efficiency of muscles and resistence of bone to stress. We found a greater consistency between feeding group and index values for C, as characterized by low orbit size, large foramen magnum angles (related to feeding posture), long maxilla (greater cutting area and access distance), marked tomial curvature (more rapid and effective cut), deeper ramus (resistance to greater dorsoventral loading), and narrow mandibular form (more narrow crania). There was also a greater mechanical efficiency in MS and BS compared to C, in terms of elevator and lateral muscles that move the head laterally, and a greater length of the mandibular symphysis in BS compared to C and MS. These results are discussed in relation to feeding behavior plasticity and phylogenetic relationships among the raptors we analyzed.