Kinematics of Feeding Behavior in the American Toad (Anaxyrus americanus): Vertical Limits of Prey Capture
Date of Award
Scott M. Boback
Since 2011 the Dickinson College Farm has been used as a living laboratory for student researchers, investigating organisms within an Integrated Pest Management (IPM) system. IPM is a technique used to control pest insects without use of harmful pesticides. Recent research investigating diet composition of the American toad (Anaxyrus americanus) suggests toads consume a variety of invertebrate organisms on the Dickinson College Farm including some pest insects. The proportion of pest insects susceptible to predation by toads is, however, currently unknown. This project addresses this question, studying the kinematics of toad feeding behavior to characterize terrestrial and elevated prey capture. To measure these parameters high-speed videography (500 fps) using a Miro Phantom EZ1 camera toad behavior was recorded when presented with live crickets, at varying heights above ground. Video analysis of morphological landmarks was carried out using Tracker video analysis software. Results indicate that predation of insects elevated off the ground requires different kinematics relative to predation of terrestrial insects. As hypothesized, features of forelimb and hind limb movement, lunge distance, and initial body position angle differed between these feeding behaviors. Differences were also observed for duration of approach and maximum tongue reach. Maximum forelimb extension, initial body position angle, lunge distance, and initial distance from prey were all found to be positively correlated with prey height. Toads were documented capturing prey at elevations between 1.1 to 2.8 times their SVL. Study of maximum height of success showed that vertical limit of successful prey capture was not correlated with snout to vent length (SVL). This study indicates that terrestrial and elevated capture differ significantly with longer durations of feeding sequences and substantial use of the legs and forelimbs in thrusting and deceleration observed in elevated capture. Data from both video and maximum predation height support that American toads have the potential to be effective predators of pest insects in agro ecosystems but that a feeding limit does exist that limits their ability to impact some aerial and arboreal pests.
Brown-Moffitt, Surya, "Kinematics of Feeding Behavior in the American Toad (Anaxyrus americanus): Vertical Limits of Prey Capture" (2017). Dickinson College Honors Theses. Paper 268.