The actively foraging desert lizard Pedioplanis husabensis (Husab Sand Lizard) behaviorally optimizes its energetic economy

The Husab Sand Lizard (Pedioplanis husabensis Berger-Dell’Mour and Mayer, 1989) is a recently described lacertid lizard endemic to a small region in the central Namib Desert. Although this species is of conservation concern, very little is known about how this lizard functions in its environment. We used the doubly labeled water method to measure the field energetics in this lizard species and we report on its foraging behavior. Pedioplanis husabensis had summer field metabolic rates (330 ± 140 J·d−1) that were similar to those of other similarly sized sit-and-wait foraging lizards (360 J·d−1), but only 43% that of an active foraging lizard of the same mass (770 J·d−1), despite using a movement-intensive, active foraging strategy. Additionally, the mean water influx rate (0.06 ± 0.03 mL·d−1) was 67% that of a desert reptile of the same size (0.09 mL·d−1). Active body temperatures were significantly lower in summer (34.3 ± 1.7 °C) than they were in autumn (36.8 ± 1.6 °C), and daily activity of lizards increased from 2.6 ± 0.9 h·d−1 in summer to 4.3 ± 1.9 h·d−1 in autumn. Relative to other species of actively foraging desert lizards, P. husabensis has lower energy requirements.