Meeting Abstract

P2.47  Saturday, Jan. 5  The kinematics of a shrike bite: force, velocity, and an argument for power in Loggerhead Shrikes (Passeriformes: Laniidae) SUSTAITA, D; University of Connecticut, Dept. of Ecol. and Evol. Biology diego.sustaita@uconn.edu

Loggerhead Shrikes (Lanius ludovicianus) are medium-sized (~50 g) passerines that feed on arthropods and vertebrates. Differences in the physical and behavioral attributes of these prey types are likely to impose disparate demands of force and speed on their jaws that might trade-off against one-another. While the relationship between bill shape attributes, bite force, and feeding ecology are explored in another paper, here I examine interrelationships among kinematic and kinetic attributes of bite performance, alone. I used high-speed (120 fps) video of shrikes biting a force transducer in lateral view to obtain corresponding measurements of bite force and upper and lower bill elevation and depression. The data indicate varying degrees of upper bill (about the craniofacial hinge) and lower bill (about the quadratomandibular joint) coordination across bite sequences within and among individuals, but in most cases upper bill depression appears to play an important role in imparting bite forces. As expected on theoretical grounds, bite velocity varies considerably more with weaker bites than with harder ones. However, shrikes appear to bite with velocities and forces that optimize power, suggesting an additional emergent performance property of potential ecological relevance.