Small grey-brown cuckoo with grey head and throat merging into a buff washed underside sometimes tinted rufous-fawn. Wings grey-brown, faintly mottled. Tail slaty brown with purple tinge, webs notched with white, especially on the inner edge. Eye is chestnut-dark brown, legs grey-pink. Length 20 to 23 centimetres.
The female is generally similar in appearance to the male except in the barred morph (not widespread) when the adult female resembles a juvenile but with less warm brown tones.
Juveniles are brown overall with plentiful buff streaks and angular feather margins. Breast is brokenly mottled, underparts are barred dark brown on pale background. Long, square-tipped tail is dark brown with lighter brown bars.
Found across northern Australia from the Kimberley to Cape York, along the east coast to central Victoria and extending inland to the lower parts of the western slopes. Also widespread in south-east Asia. A sedentary bird in the north, but south-eastern birds spend winter as far north as New Guinea, returning in August-September to the south-east to breed. In all parts it lives along the forest edge in tangled vegetation, feeding on insects and caterpillars. Only in the northern wet season does it move out into open woodlands.
The Brush Cuckoo mainly lays its eggs in open cup-shaped nests of flycatchers, fantails and red-breasted robins in the southeast and in the deeper domes of Brown-backed and Bar-breasted Honeyeaters across the north. Its eggs resemble those of the unknowing host.
¶ Genus Cacomantus is in Family Cuculidae with other cuckoos.