Some observations of the social behavior of the Arizona chuckwalla, Sauromalus obesus tumidus (Reptilia, Lacertilia, Iguanidae)
Journal of Herpetology
1978
Journal Article
12
3
327-336
Sauromalus obesus tumidus
The social behavior patterns of enclosed populations of the Arizona chuckwalla (Sauromalus obesus tumidus) were observed from 1970 to 1972. Field observations were conducted from June through August 1970 and 1974. In a challenge display a male chuckwalla compresses his trunk, partially extends his dewlap, orients laterally towards his opponent and performs rapid head nods. The head nodding follows a specific sequence: two complete up and down movements, two intermediate nods and two shorter nods. Dominant males in the enclosure and territorial males in the field are most active; they challenge and chase other trespassing males but tolerate females and juveniles. In the enclosure, subordinate males retreat from higher ranking males or assume a submissive posture. Female aggression is indicated by postural changes, chasing and biting. Sex recognition is based on posture and coloration. During copulation the male maintains a biting hold on the skin of the shoulder of the female. Under natural conditions males were territorial. Homing ability under natural conditions was observed to be accurate on sunny days. In the laboratory a dominance hierarchy and despotism developed. Supplanting behavior was not observed in the field but was common in the laboratory. The selective advantage of the lability of this social behavior is obvious in situations where limited food or other resources make it energetically unfeasible to defend a territory.