Behavioral thermoregulation in the pika Ochotona princeps: a field study using radiotelemetry

Abstract

When either the level or duration of spontaneous activity is increased over an ambient temperature range of 2–28C, the body temperature of the pika shows a slight increase; the maximum fluctuation observed was 1.0C. However, none of the changes in body temperature proved to be significantly different from that of the resting state (P < 0.05).In nature, pikas avoid hyperthermia by means of precise behavioral thermoregulation in which both duration and level of activity are regulated. A negative correlation was observed between the duration of lime spent on the surface of the rocks, and the surface ambient temperature, over a range of 3–27C. Between 0930 and 1930 h, as the surface ambient temperature increased, the percentage of observations in which the pika was below the rocks increased, and vice versa. By engaging in short bursts of surface activity (usually less than a 3.5-min duration) followed by retreat to the cooler microclimate beneath the rocks, pikas are able to regulate their body temperature precisely at a level only 2–3C below the upper lethal temperature.