Stop, then go! Rapid acceleration offsets the costs of intermittent locomotion when turning in Florida scrub lizards

Abstract

AbstractIntermittent locomotion is a common locomotor mode in small vertebrates. Pausing is thought to aid in locating a predator or prey, enhancing crypsis, lowering energy costs, and/or maneuvering around obstacles or toward a refuge. Many lizards flee predators by turning into potential refugia and subsequently pausing, presumably to conceal themselves. Intermittent locomotion may be associated with turning by allowing an animal time to assess its surroundings and/or decreasing the likelihood of losing its footing. In this study, we quantify locomotor performance and the use of intermittent locomotion in Florida scrub lizards (Sceloporus woodi) when navigating either a 45° or 90° turn. Lizards paused in 92.91% of all trials, and yet despite pausing, instantaneous speed was not different entering or exiting the turn. This result suggests that turning comes at minimal cost to forward speed for lizards under these conditions. Pausing during a turn, however, did slow speed in the turn. Interestingly, the speed in the turn did not differ in trials with a pause before the turn versus trials without a pause. The angle of the turn also had no effect on whether lizards paused. We found that lizards increase peak acceleration following pauses to compensate for lost speed during the pause, providing a mechanism that may minimize negative fitness effects associated with slow running speeds and allow intermittent locomotion to be such a common strategy in lizards.