Daily and seasonal temperatures in the burrows of African rodent moles

Abstract

Burrow, soil surface and ambient temperatures were compared in mesic and xeric climates in tropical and sub-tropical Africa. In all the areas studied there was a similar daily pattern of change in the temperature of the soil surface and the burrow air but the magnitude of the changes and the time of day at which maximal and minimal temperatures occurred varied. In all areas, changes in burrow temperature were of a lower amplitude than those above ground. Mean monthly subsoil temperatures show that the annual amplitude of temperature fluctuation is greatest at the soil surface and diminishes with increasing depth. At depths greater than 0,6 m mean annual soil temperatures vary minimally. The depth at which this occurs is to some extent dependent upon soil type and ground cover. The mean daily burrow temperatures also show that the daily amplitude of temperature fluctuation is less with increasing depth. The subtropics show marked seasonal changes in mean burrow and above-ground temperatures whereas the available information in the literature shows that little seasonality occurs in the tropics. We suggest that this regional difference in temperature profiles may lead to the seasonality in breeding and in moulting shown by rodent moles from the subtropics and for the absence of this seasonality in rodent moles from the tropics.