Meeting Abstract

9.4  Jan. 4  Bite and grip performance in relation to killing behavior of North American accipiters and falcons SUSTAITA, Diego*; HERTEL, Fritz; University of Connecticut; California State University, Northridge diego.sustaita@uconn.edu

Raptors exhibit a wide diversity of attack strategies to disable and/or procure their prey, but ultimately kill using either their beaks or talons, or both. Thus, bite and grip forces are ecologically important parameters that have direct implications for their subsistence. Whereas falcons tend to rely heavily on their beaks for killing, most hawks primarily use their feet. Consequently, falcons are expected to achieve relatively greater bite forces, and conversely hawks are expected to generate relatively greater foot forces. The primary objective of this study was to complement results based on anatomical force estimates produced in a previous study, with direct measurements of actual bite and grip performance. To this end, captive and wild-caught accipiters and falcons were induced to bite and grasp modified electronic load cells. Our results indicate that falcons tend to bite significantly harder than accipiters, and accipiters grip significantly harder than falcons for any given body mass, but by a smaller margin. Furthermore, bite force tends to increase isometrically with body mass in both groups. Grip force, however, increases allometrically in accipiters, but does not differ from isometry in falcons. The anatomically-derived measurements of force tended to overestimate the actual performance measurements, but the two are correlated, and therefore these data provide an important link between morphology and killing behavior in these raptors.