Bush stone-curlew

The bush stone-curlew or bush thick-knee (Burhinus grallarius, obsolete name Burhinus magnirostris) is a large, ground-dwelling bird endemic to Australia. Its favoured habitat is open plains and woodlands, where it stalks slowly at night in search of invertebrates such as insects. Its grey-brown coloration is distinguished by dark streaks, its eyes are large and legs are long. It is capable of flight, but relies on the camouflage of its plumage to evade detection during the day; the bush curlew adopts a rigid posture when it becomes aware of an observer. Both sexes care for two eggs laid on the bare ground, usually sited near bush in a shaded position or next to a fallen branch.

A species of Burhinus, a genus of large-eyed and long-legged terrestrial foragers known as thick-knees, it is slender in form and a grey and brown colour with distinctive markings. The bird has conspicuous dark streaks over the buff and greyish white feathers of the upperparts and spotted markings on the wings. The plumage at lower side of the bird is also strongly streaked with dark brown over white and buff feathers.

The total length of the species, including a bill around 45 mm and tail 180 mm, is 550 mm; the wingspan approaches 1 m across.

Black flight feathers on the wing reveal a light buff patch when extended, and the plumage has a light area at the shoulder.

The head is distinguished by a band of dark feathers over the eye and down the neck, and a buff colour at the forehead and brow over the eye. The iris is bright yellow; bare skin near the eye is black. The long legs of the species are an olive-green colour, and the bill is darkish in tone.

The sexes are similar, with juveniles displaying a paler plumage that otherwise resembles the adults.

This stone-curlew's voice is loud and can be heard at a great distance. The call of "weeloo" has an eerie and plaintive tone and is a familiar sound of the night in the Australian bush.

The frequency of calls increases when weather conditions are changing, especially when rain is approaching an area.

Several individuals may join their voices in chorus, greatly intensifying the extraordinary quality of their nocturnal calling.

The coloration of the eggshell is generally a stone grey with brownish blotching, although this is variable and often matches the environment to provide camouflage. Size of the egg is also variable, on average it is 53 × 39 mm, yet differences in nearby nests or between the two eggs of the same brood are recorded.

No other Australian bird resembles the bush curlew. Another species of the family, the beach stone-curlew also known as a wee-lo, is distinguished by its plumage and larger bill and is only found at the coast. Confusion with the nightjars is possible, but the species of Caprimulgus are smaller and fly in a different manner.