Thermoregulatory Behavior of the Hawaiian Monk Seal (Monachus schauinslandi)

Abstract

The behavior of Hawaiian monk seals at French Frigate Shoals was studied in order to obtain information on their adaptation to a tropical climate. The seals were unable to remain on the dry beach platform during the day except during very high winds, extensive cloud cover, or rain. The seals characteristically moved down to wet sand on the beach slope during the day and returned to the beach platform at night. The frequency with which the seals changed their posture appeared to be related to the prevailing microclimatic conditions. For the most part, the seals lay in postures that exposed their ventral pale-colored hair coat to the atmosphere. The temperature of this surface was significantly lower than that of the darker dorsal coat. The seals were extremely inactive while ashore; their respiratory pattern included long periods of breath-holding, and the heart rate during breath-holding was low. These features were considered to be compatible with a low level of metabolic heat production and to be adaptive to heat exposure.