The brown songlark (Cincloramphus cruralis), also Australian songlark, is a small passerine bird found throughout much of Australia. A member of the family Locustellidae, this species is notable for sexual size dimorphism, among the most pronounced in any bird. It is a moderate-sized bird of nondescript plumage; the female brownish above and paler below, the larger male a darker brown.
Male brown songlarks are 23–25 cm long versus 18–19 cm for females, and may weigh 2.3 times as much. They are probably the most sexually dimorphic passerine in the world in size difference, as well as likely the largest species in the family Locustellidae. In general, the birds have a dusky pale-streaked with darker brown plumage and pale eyebrows. The underparts are brownish-white in the female, darker brown in the male. Breeding males may display a cinnamon colour. The eyes and bill are black, and the legs grey. Juveniles are smaller and paler with pinkish-brown bills. The call has been described as loud and creaky. The male is the principal singer, calling from perches or when rising above breeding territory.