Roadrunners: energy conservation by hypothermia and absorption of sunlight.

Roadrunners sunning in artificial sunlight consume oxygen at standard (basal) levels at ambient temperatures as low as 9.0 degrees C. Energy savings of sunning roadrunners averaged 551 calories per hour. In the dark, birds may undergo hypothermia. Hypothermic roadrunners can elevate their body temperatures to normal levels by sunning, at reduced metabolic cost.