Using an Infrared Temperature Sensor to Study Microhabitat Selection in Captive California Sea Lions (Zalophus californianus)

Abstract: We used the Professional Equipment T7350 Series Infrared Thermometer to measure the temperature of haulout areas and pool water available to three adult California sea lions (Zalophus californianus) at the Peoria Zoo. The handheld, battery-operated sensor was pointed at a surface, a red laser light indicated the location of the reading, and the temperature was read on the digital display. To test its reliability over distance, repeated measurements were taken on each sea lion held at station by a trainer in an indoor enclosure at 1 and 3 m away. Ambient air temperature and the temperature of eight haulout areas, as well as the water temperature in the three pools, were taken at 15-min intervals during zoo operating hours each week over a 10-mo period; weather conditions ranged from cold winter (-2.8° C [27.0° F]) to hot summer (37.8° C [100.0° F]) days. At the same intervals, each of the sea lion’s skin temperatures (at the dorsal torso, fore-flipper, and hind-flipper) were measured and their location in the exhibit was noted. In addition, each sea lion’s behavior was scored into one of eight classes when the measurements were taken. The sensor could not measure the body temperature of a submerged sea lion, only the water temperature. However, the infrared thermometer accurately measured the sea lion’s skin temperature while on land, exposed skin when the animal was partially submerged, and the temperature of the substrate. Since the unit is inexpensive, noninvasive, portable, and takes readings at a reasonable distance, the infrared temperature sensor is a useful tool to help zookeepers monitor the temperatures of the microhabitats of the captive animals. In addition, the sensor could have applications for studies of thermoregulation or health in captive and wild pinnipeds. Some topics for further research are identified, which would help clarify the overall usefulness of this infrared sensor.

Key Words: thermoregulate, remote sensing, microhabitat, body temperature, California sea lion, Zalophus californianus

Document Type: Research article

DOI: 10.1578/AM.34.2.2008.212

Page Numbers: 212-228

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