Function of Body Coloration in Green Anoles (Anolis carolinensis) at the Beginning of the Breeding Season: Advertisement Signaling and Thermoregulation

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We examined two hypotheses regarding the function of body coloration in green anoles Anolis carolinensis. First, their bright green coloration serves as a social signal advertising territorial possession or dominance. From this hypothesis, two predictions derive: 1) most anoles with bright green coloration are adult males; and 2) adult males with bright green coloration tend to perch at higher positions to send the signal to broad areas. Another hypothesis, which is not exclusive to the former one, is that the dark coloration functions to raise their body temperature. From this hypothesis, three predictions derive: the anoles with dark (brown) coloration are 1) observed more frequently in the morning than in the daytime, 2) more likely to engage in basking behavior than in other behaviors, and 3) observed more frequently when air temperature is low. We tested these predictions in the field at the beginning of their breeding season. The results supported the advertisement signal hypothesis, but not the thermoregulation hypothesis. However, since our negative results against the latter may actually be attributable to relatively low air temperature throughout our observation period, additional observations are desired to verify rejection of the thermoregulation hypothesis as resulting from the present study.