The Protelinae (aardwolves) are not treated as a separate subfamily, but included in the Hyaeninae. Aardwolves also have scent glands on the forefoot and penile pad. Aardwolves are shy and nocturnal, sleeping in burrows by day. Unlike other hyenas, aardwolves do not scavenge or kill larger animals. Aardwolves live in open, dry plains and bushland, avoiding mountainous areas. Aardwolves are not fast runners nor are they particularly adept at fighting off predators. Aardwolves generally achieve sexual maturity at one and a half to two years of age.