Body temperature, thermal tolerance and influence of temperature on sprint speed and food assimilation in adult grass lizards, Takydromus septentrionalis

1. We studied in field and laboratory experiments several aspects of the thermal biology of adult lacertid lizards (Takydromus septentrionalis). 2. The selected body temperature and the critical thermal maximum averaged 30.0 and 42.3 degrees C, respectively; the critical thermal minimum of males and females averaged 3.9 and 5.9 degrees C, respectively. 3. The lizards in May exhibited lower and more variable active body temperatures than did the lizards in July, because of lower and more variable air and substrate temperatures in May. 4. The sprint speed generally increased with body temperature within the range of 17 to 32 degrees C and decreased at temperatures >32 degrees C. 5. Within the range of 26 to 36 degrees C, body temperature influenced food assimilation primarily by affecting the food passage time, whereas it only slightly affected the daily food consumption, the apparent digestive coefficient and the assimilation efficiency. The food passage time decreased with increasing body temperature. Copyright (C) 1996.