Basking Behavior of the Hawaiian Green Turtle (Chelonia mydas)

Abstract

Observations were made on green turtles basking on the white sand beaches at French Frigate Shoals in the northwestern Hawaiian Islands. The highest rectal temperature recorded from the basking turtles was 31.3°C, but the surface temperature of the carapace attained values as great as 42.8°C. During basking, the turtles flipped sand onto their carapaces, but they did not appear to orientate their position in relation to the sun. The duration of basking was inversely related to the mean temperature of a black globe, and the basking beaches were relatively cool. The pattern of breathing during basking consisted of periods of breath-holding alternating with single breaths. The amount of time that the turtles basked varied from 0.3 to 7.5 percent of the total time they were under observation. The biological significance of basking and the advantages that might accrue to Hawaiian green turtles from their unique basking behavior are discussed.