Thermoregulatory aspects of behavior in the blue spiny lizard Sceloporus cyanogenys (Sauria, Iguanidae).

1. The thermal relations of blue spiny lizards, Sceloporus cyanogenys, were studied in laboratory habitats which were designed to allow the expression of a large repertoire of natural behavior patterns. Body temperatures obtained with fast-reading thermometers and by radio telemetry from implanted transmitters were correlated with postures and activities. 2. The morning emergence of lizards was found to be cued by light, often in the absence of immediate thermal reinforcement. 3. Two basking postures which altered a lizard's air and substrate thermal interfaces could be distinguished. The environmental and body temperature correlates of these postures were not appreciably different, and the change from one posture to another could not be interpreted as thermoregulatory. 4. When thermal conditions permitted, basking continued up to the attainment of the maximum voluntary body temperature (38.7 C), and was then followed by perching. 5. The body temperature correlates of perching had a range and mean much like the "normal activity range" of other species of Sceloporus (28.2-38.7 C, X= 35.2). 6. Defecation occurred mostly in the morning towards the end of the basking period, but had a broad thermal range (27.5 to 35.7 C). 7. The range of body temperatures during feeding was broad (25.3-38.5 C), but that of foraging was much narrower (34.3-38.7 C).