Rüppell's foxes are monogamous and either crepuscular or nocturnal. They usually spend the day resting in their underground dens, but in winter they are occasionally active during the day. They use two different types of burrows, which are strictly separated: the breeding dens and the resting dens. Outside of the breeding season, these are small dens that can hold only one adult fox, and the fox changes dens frequently, on average about every 4.7 days. Breeding dens are larger, and occupied by a pair of adults and their kits. Such dens can sometimes have more than one entrance, although this is unusual. They make a series of short barks during mating and, at other times, can also produce hisses, trills, and sharp whistles. They have been reported to wag their tails, like domestic dogs.