The Mountain Owlet-nightjar lives in New Guinea's mountain forests and is active at night. It has rufous and brown plumage forms and roosts in hollows by day.
Its plumage occurs in rufous and brown forms, with intermediate colors also present. The sexes are similar.
It is nocturnal and roosts in hollows by day. It catches insects and earthworms on the ground beneath the forest canopy and in clearings.
It gives a sharp falling wek-like call, singly or doubled, sometimes with a raspy quality.
At Mt Missim, Papua New Guinea, in October–December 1986, faeces from six roost sites and 18 captured birds, supplemented by stomach samples, contained mostly beetle remains, with moths or butterflies, flies and orthopteran insects also recorded.
In that Mt Missim study, samples containing earthworms were collected after heavy or prolonged rain, when many worms emerged onto the forest floor.
It has a dark head, pale collar and barred back and tail.
An extinction-risk assessment has not been added yet.