Distribution
Rhabdomys intermedius is endemic to the southern interior regions of South Africa where it occurs in a narrow band through the Karoo, wedged between R. pumilio on the coast and R. bechuanae further north (du Toit et al. 2012, Monadjem et al. 2015). Rhabdomys intermedius was described from Cradock and Port Elizabeth in the Eastern Cape, as well as Deelfontein in the Northern Cape; this species mostly represents the central clade (du Toit et al. 2012). Further molecular research and vetting of museum specimens is needed to more accurately delineate the distribution ranges of the various Rhabdomys species.
Population trend
Trend
No national abundance information is available for this species and, although they can be locally and temporally abundant, their densities are known to fluctuate (Happold 2013). Fast growth, followed by population crashes, occur frequently. The species commonly occur in high numbers, often significantly higher than all other co-occurring small mammal species (Happold 2013). A comparative study between the Rhabdomys spp. in the arid Succulent Karoo and those in the moist grassland habitats of South Africa found that, as a result of increased rainfall levels, Rhabdomys in grassland regions exhibited much longer breeding seasons (Schradin and Pillay 2005). Additionally, high annual survival rates in the Succulent Karoo resulted in significantly higher population densities compared to drier grassland regions (Schradin and Pillay 2005). In the Succulent Karoo, average population densities of 36.6 ± 21.2 mice / ha (N = 5 groups) were reported in September, increasing to a peak of 171.1 ± 40.9 mice / ha (N = 7 groups) in December, and then declining through the rest of summer and into winter (Schradin and Pillay 2005). In other parts of South Africa, densities of 35–93 individuals / ha, and 30–300 individuals / ha were recorded in the Highveld grasslands (Brooks 1974) and the Cape Flats (David and Jarvis 1985), respectively.
