Seasonal acclimatization and thermoregulation in the pouched mouse Saccostomus campestris

Abstract

The pouched mouse Saccostomus compestris, a nocturnal, fossorial rodent, is widely distributed in the Southern-African subregion. Seasonal acclimatization of mechanisms of thermoregulation and body mass were studied in this species under the natural photoperiod conditions prevailing in Pretoria during January–February and July–August at room temperatures of 23.2–28.1 and 9.8–18.2°C, respectively. The following parameters were measured or calculated: body mass, oxygen consumption and body temperature at various ambient temperatures, minimal overall thermal conductance and capacity for non-shivering thermogenesis. In winter-acclimatized pouched mice, body mass, resting metabolic rates and non-shivering thermogenesis capacity are higher than in summer-acclimatized mice, while lower critical point and minimal thermal conductance are higher in summer-acclimatized mice than in winter-acclimatized. The seasonal changes of the studied parameters, may help explain the ability of this species to cope with its habitat in the two different seasons.