Behavioral and physiological thermoregulation in male cicada killers (Sphecius speciosus) during territorial behavior.

(1) Male cicada killers had elevated, apparently regulated, thoracic and head temperatures during territorial perching and patrolling in full sunshine. (2) Dead, dry wasps reached near-lethal temperatures on the bare ground, and were hotter with their bodies perpendicular to the sun's rays, as opposed to parallel. (3) The percentage of males perching on the ground, their perch duration, and the percentage oriented perpendicular to the sun decreased during the mid-day. (4) Males used a low-amplitude wing vibration early and late in the day, perhaps boosting heat production. (5) Changes in behavior were related to changes in the intensity of solar radiation.