Microhabitat use across the sleep-wake cycle in predominantly arboreal lizards

Many organisms face alternative selective pressures across cyclically changing environments such as the diel cycle. Energetic and spatial constraints, among other issues, preclude independent day and nighttime or wakeful and sleeping responses to these contrasting sets of selective forces. We tested for behavioral similarity in microhabitat use during daytime wakeful and nighttime sleeping periods in Anolis lizards. We collected 1256 datapoints of sleeping perch height and substrate for 51 species and compared these data to published data on active perch use for these species. We demonstrate that species perch at similar heights but use significantly different perch substrates during sleep and wakefulness. The diel similarity in perch height may indicate a surfeit of adequate sleeping perches within a species' home range. The difference in perch substrate, wherein individuals tend to sleep on compliant perches, likely reflects the special predation risks encountered at night during sleep.