Speeds and Movement Patterns of European Lacertid Lizards: A Comparative Study

Abstract

Four species of lacertid lizards (Podarcis muralis, P. pityusensis, Lacerta viridis, and L. trilineata) moving in laboratory arenas alternated bursts of locomotion with short (<1 s) pauses. Variables relating to this movement are compared under two conditions, defined as 'standard' and 'fleeing,' with values previously recorded for Lacerta vivipara. Mean speeds of the five species (U, in cm s-1) increased with increasing body mass (M, in g) as U = 15.1 M0,17. When expressed in body lengths per second, however, mean speeds decreased with increasing body mass. The ratio of 'fleeing' to 'standard' speed was lower in adult L. vivipara than in adults of P. muralis, P. pityusensis, and L. trilineata and was lower in juvenile L. vivipara than in juvenile L. viridis; possible reasons for these differences are discussed. The incidence and duration of pauses in the five species decreased with increasing body mass. Locomotion in many species of quad- rupedal lizards consists of short bursts of walking or running which are inter- spersed with short pauses. Recent work on the European viviparous lizard Lacerta vi- vipara has shown that mean burst duration, mean burst speed, and mean pause dura- tion may vary according to defined exper- imental conditions (Avery et al., 1987) and also with body temperature (Avery et al., in preparation). Casual observation sug- gested that in other species, under the same conditions, the values for these variables