FIELD METABOLIC-RATE AND WATER FLUX IN FREE-LIVING BIBRONS AGAMA (AGAMA-IMPALEARIS, BOETTGER, 1874) IN MOROCCO

Many natural history characteristics of agamid and iguanian lizards su ggest that these closely related groups occupy similar kinds of niches in the Old and New World, respectively. Do these similarities also in clude physiological properties? We measured field metabolic rates and water flux rates, with doubly labeled water, in Bibron's agama (Agama impalearis) during the breeding season in the field in Morocco, and co mpared these with values expected from regressions for an iguanian liz ard having a similar autecology. Water influx and field metabolic rate s of Bibron's agamas during our study were much higher than in iguania n lizards and tended to be higher than in other agamids as well. The u nusual occurrence of rain showers during our measurements triggered mu ch above-ground activity of termites, and this may have stimulated aga mas to feed voraciously. Diet analyses revealed that termites were the major food consumed and that termites had unusually high water conten ts (80% water) for insects, providing abundant water to the agamas. Th e lizards apparently did not drink rain water. Rates of water influx ( ml/day) in Bibron's agama and in four other desert-dwelling agamid liz ards scaled with body mass (in grams) according to the relation ml/day = 0.0835 g(0.777) (r(2) = 0.64), which differs from the relationship for desert-dwelling sceloporine lizards (mi/day = 0.0380 g(0.767), r(2 ) = 0.53).