abstract

California sea lions (Zalophus californianus) have a limited ability to thermoregulate at high ambient temperatures during terrestrial phases of their life cycles. This may be in part because of their adaptations to living in an aquatic environment, and their ability to limit heat loss in water. California sea lions are sensitive to higher ambient temperatures and when compared to most other terrestrial animals, are reported to have a very low upper critical air temperature of approximately 22 degrees C. This suggests special exhibit design considerations should be made for them in captive situations. Measurements of wet California sea lion coats indicate they absorb 91.6% of all types of shortwave radiation, making a wet sea lion very efficient at rapidly warming its body temperature. Dry sea lion coats are less solar-absorbent. The thermal properties of materials, shortwave and longwave reflectance of different colors painted on the walls, and the amount and quality of the shade should be considered carefully in planning captive habitats for sea lions.