Poe, S. & T. L. Kennedy

Sleeping behavior, sleep duration, and the sleep–wake transition in two species of Puerto Rican anoles. pp. 329-337.

Abstract. Sleeping behavior across the diel period is understudied in squamates. We documented behavior during sleep and the sleep–wake transition in an assemblage of Anolis lizards (anoles) in Puerto Rico. We performed both field population surveys and longitudinal studies of individuals overnight. Fifty-six of 59 individuals tracked longitudinally chose an arboreal sleeping perch on light vegetation at sundown and stayed nearly or completely motionless on that perch until sunrise. Sleep duration in A. cristatellus and A. krugi was 12 to 13 hours across species and individual/population studies, an interval that corresponded to the dark nighttime period. Diel transitions between sleep and wakefulness were found to be brief; in the extreme case of the change between sleeping to wakefulness recorded in our population study, the period wherein both sleeping and wakeful anoles was observed was just two to eight minutes. Anoles in our studied assemblage were extraordinarily scarce during a brief, ~1 hour period after sleep and before daytime active behavior. This “morning retreat,” possibly involving hiding in or below vegetation, may reflect antipredator behavior whereby an ectotherm becomes secretive while compromised due to overnight sleep and before basking is sufficiently beneficial for emergence.

Key words. Squamata, Sauria, Anolidae, Ctenonotus clade, lizards, sleep site, vertebrates.