The Southern African Vlei Rat is a large-sized rat with dense and continuously replaced shaggy fur. The head is large, the ears small, and the tail short. The dorsal parts are generally gray, brown, or black. The ventral parts are some shade of paler or darker grey. All of its digits are clawed, and the hind claws are longer than the fore claws. The head-and-body length is about 160 mm (6.3 in) and the tail about 100 mm (4 in). Both males and females have a similar mean mass of 143.7g.
The range extends from the far South Western Cape of South Africa, around the southern and eastern coast and adjacent interior, to subtropical regions in southern Natal. This part of its range includes Lesotho. Further north, it no longer occurs around the actual coast. Inland however, its range extends north to tropical areas, nearly to the northern boundary of the Transvaal, including parts of Eswatini. An apparently isolated population occurs still further north in tropical eastern Zimbabwe and adjacent Mozambique.Its habitats include temperate low-altitude swamps and grassland, and subtropical and tropical high-altitude grassland, swamps, and plantations. It is a terrestrial species that lives above ground in an open, bowl-shaped nest made of shredded grass near marshy areas with a lot of vegetation.
The Southern African Vlei Rat is mainly active at dusk and dawn. Most are diurnal, although some Vlei Rats show nocturnal activity. It shares and creates runways with other coexisting species through the vegetation as it forages on the green vegetation on which it feeds.
The Southern African Vlei Rat is a k-strategist, quadrupedal, and can rapidly run along runways. They are able to swim if needed. They often use their forepaws to eat and discard food in piles by runways, as well as grooming and washing their face.
This rat is solitary and aggressive towards other members of the species. Adult males have a home range of about 1,730 m2 (18,600 sq ft) and maintain a small home territory around the nest site. It communicates through olfactory signals by anal-gland marking of their territory. There is a hierarchy in aggression: males and females who have mated, then males and females who have not mated, respectively. When same-ranking individuals encounter each other, they start fighting and chasing each other, ending in serious wounds until one animals flees or shows submissive behavior. Submissive behaviors include the rats in an upright posture exposing their stomach and chattering.
Since they are non-burrowing, they keep warm through nonshivering thermogenesis and have low thermal conductance. They have low metabolic rates which may be why they can feed on low quality food.
Their predators are mainly barn owls and grass owls, but also include pythons, mole snakes, wildcats, mongooses, and cape clawless otters.
