Potoo Bird

Behaviour
The potoos are highly nocturnal and generally do not fly during the day. They spend the day perched on branches with the eyes half closed. With their cryptic plumage they resemble stumps, and should they detect potential danger they adopt a "freeze" position which even more closely resembles a broken branch. The transition between perching and the freeze position is gradual and hardly perceptible to the observer.
The English zoologist Hugh Cott, describing Nyctibius griseus as "this wonderful bird", writes that it
habitually selects the top of an upright stump as a receptacle for its egg, which usually occupies a small hollow just, and only just, large enough to contain it... the stump selected had thrown up a new leader just below the point of fracture... and the birds sat facing this in such a way that when viewed from behind they came into line and blended with the grey stem.