Meeting Abstract

91.3  Monday, Jan. 6 14:00  Come on baby, let’s do the twist: the kinematics of killing in Loggerhead Shrikes (Passeriformes: Laniidae) SUSTAITA, D.*; RUBEGA, M. A.; FARABAUGH, S. M.; Brown University; University of Connecticut; San Diego Zoo Global diego_sustaita@brown.edu

Shrikes use their beaks for procuring and processing their arthropod and vertebrate prey. Their distinctive hooked bills and powerful bite capabilities are thought to play particularly important roles in dispatching vertebrate prey. We examined the relationship between prey handling performance and bill shape using high-speed video analysis of feeding behavior of captive adult and juvenile San Clemente Loggerhead Shrikes, coupled with geometric morphometrics of upper bill shape. Once shrikes gained purchase on the nape of their prey with their beaks, they typically shook it by way of rapid (6-17 Hz; 49-68 rad/sec) head oscillations (about the rostrocaudal axis) that accelerated the bodies of their prey about their own necks at g-forces of up to 18 g. Adult shrikes showed greater propensities to use head-rolling to dispatch prey, and greater oscillation frequencies. Juveniles demonstrated lower capacities for maintaining a beak-hold on prey, likely resulting from their relatively underdeveloped bill hook and tomial structures. Thus, when tackling relatively large vertebrates, shrikes apparently use their prey’s own body inertia to facilitate immobilization by damaging the cervical vertebrae and spinal cord. However, the structure of the bill, coupled with jaw speed and force, may also play important roles for maintaining bill contact with prey during handling.