Seasonal acclimatization and thermoregulation in the pouched mouse Saccostomus campestris

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.