Fig. 4. (A) Frequency distributions of dorsal skin temperatures for cold and hot exit temperatures based on the means and standard deviations averaged across hatchlings. Distributions are presented separately for hatchlings incubated at 23°C (blue), 26°C (green) and 30°C (red). (B) Transition probabilities calculated using the dual-limit stochastic model of Barber and Crawford (1977). The heating transition curves (solid lines) indicate the probability that a hatchling, behaving in a complex thermal environment, would move toward heat; the cooling transition curves (broken lines) indicate the probability that a hatchling would move away from heat. The point of intersection of the two curves indicates an equal likelihood of moving toward or away from heat. As shown most clearly in the insert, the dorsal skin temperature at which this equilibrium point occurs increases systematically with incubation temperature.