Energy Utilization in the Lizards Sceloporus graciosus and S. occidentalis

Abstract

Three Sceloporus graciosus which gained weight (+ 0.37 g) during measurement assimilated 83-88 cal/g/day when maintained on a Tenebrio larvae diet. One S. graciosus which maintained constant body weight assimilated 73 cal/g/day. Five S. occidentalis that had a mean weight gain of 3.70 g had a mean energy assimilation of 36 cal/g/day. It was calculated that a male S. graciosus, feeding only on Tenebrio larvae, would ingest 78,000 cal during its first three years of life, of which 64,000 cal would be assimilated. Ap- proximately 61% (39,000 cal) of the total energy assimilated would be used in metabolism. * * * The subject of energy budgets and measurements of energy assimilation of reptile species has not been extensively studied. However some reports have appeared giving estimates of energy utilization. McNab (1963) using the respirometry data of Dawson and Bartholomew (1956) and the temperature data of Bogert (1949), calculated the daily energy expenditure of Sceloporus occidentalis. Johnson (1966) estimated the daily energy assimilation of three species of lizards. Alexander and Whitford (1968) calculated the energy requirements of a population of Uta stansburiana.