It is nocturnal and has a distinctive "oom oom oom" call. It sounds a bit like a motor that won't start.

The NSW National Parks and Wildlife Services has some great details on the Tawny Frogmouth including its call.

It is a common misconception (which I for one had) that a Tawny Frogmouth is also called a Mopoke and makes the plaintive "mopoke" call at night.

In fact a Mopoke is a Southern Boobook Owl and it makes the call.

The brilliant Owl Pages web-site explains this.

The marbled feathers of the Tawny Frogmouth show how it blends in with the trunk of trees and dappled light.

The Tawny Frogmouth is not an owl - being more closely related to a Kookaburra.

It is about 50cm from head to tail.

The male (as shown here) has greyer plumage; the female's is browner.