It has recently come to my attention that several websites (e.g. wikipedia) report that male anoles produce ultrasonic hisses while fighting. I’ve been trying to track down the source of this information, but I can’t find any reference to ultrasonic sound production in anoles in the scientific literature. Does anyone know the source of this information? Can anyone confirm that anoles are capable of producing ultrasonic sounds? I’d be grateful to anyone who can shed any light on this rumor.