Field Energetics and Foraging Mode of Kalahari Lacertid Lizards (original) (raw)

We examined the energetic costs associated with foraging mode in the widely foraging lizard Eremias lugubris (mean mass 3.83 g) and the sit-and-wait lizard Eremias lineoocellata (3.27 g). These lizards are broadly sympatric in the Kalahari desert. Individuals of both species were probably abroad every day, but the wide forager was abroad for much shorter periods (2.75 Wd vs. 10.25 h/d). Nevertheless, the widely foraging species had significantly higher field metabolic rates (800 vs. 544 J/d, as measured with doubly labeled water), feeding rates (metabolizable energy of 1165 vs. 739 J/d), production rates (365 vs. 195 J/d) and water influx rates (0.285 vs. 0.156 m u d ) . Measurements were made before the reproductive season began; there were no significant differences in these measures between sexes within either species.