Movement patterns of lacertid lizards: effects of temperature on speed, pauses and gait in Lacerta vivipara

Abstract

AbstractLacerta vivipara emerging from their overnight retreat before they had the opportunity to thermorcgulate moved with an alternation of locomotor bursts and pauses. Mean speed during bursts of locomotion fell with decreasing temperature from 3.21 snout-vent lengths (SVL) s-1 at the activity temperature (Tact ∼ 33°C) to 0.15 SVL s-1 at 5°C. Between Tact and 19°C the reduction was small (Q10 = 1.12) and statistically not significant; between 19°C and 5°C the change was very much greater (Q10 = 7.7). The pauses between locomotor bursts increased progressively in duration over the whole range of decreasing temperatures from Tact to 5°C, although the change from Tact to 23°C was not significant. Gait changed progressively from almost simultaneous movement of contralateral diagonal limbs at Tact to independent movement of limbs in the sequence LF, RH, RF, LH at 7°C, with increases in the mean duty factor of individual feet from 0.50 to 0.76 and in the proportion of time for which 3 or 4 feet were in simultaneous contact with the ground from 0 to 0.92.