Measuring 19–21.5 cm (7+1⁄2–8+1⁄2 in) in length, the willie wagtail is contrastingly coloured with almost entirely black upperparts and white underparts; the male and female have similar plumage.

It is widely featured in Aboriginal folklore around Australia and New Guinea in a variety of roles, from stealer of secrets and liar to a good omen for successful crops.

[9] The name had been in use colloquially for the pied subspecies of the white wagtail (Motacilla alba) on the Isle of Man,[10] and Northern Ireland.

[11] Other vernacular names applied include shepherd's companion (because it accompanied livestock), frogbird, morning bird, and Australian nightingale.

[17] In Bougainville Island, it is called tsiropen in the Banoni language from the west coast,[18] and in Awaipa of Kieta district it is maneka.

[31] The male and female have similar plumage; the head, throat, upper breast, wings, upperparts, and tail are all black, with a white eyebrow, "whiskers" and underparts.

[33] Widespread and abundant, the willie wagtail is found across most of Australia and New Guinea, the Solomon Islands, the Bismarck Archipelago, and eastern Indonesia.

It is sedentary across most of Australia, though some areas have recorded seasonal movements; it is an autumn and winter visitor to northeastern New South Wales and southeast Queensland, as well as the Gulf Country and parts of Cape York Peninsula in the far north.

[36] The willie wagtail was released in Hawaii around 1922 to control insects on livestock, but the introduction was unsuccessful and the last sighting was at Koko Head in 1937.

[39] It has responded well to human alteration of the landscape and can often be seen hunting in open, grassed areas such as lawns, gardens, parkland, and sporting grounds.

It has been observed to build its nest in the vicinity of those of the magpie-lark (Grallina cyanoleuca), possibly taking advantage of the latter bird's territoriality and aggression toward intruders.

Parents will stop feeding their fledglings near the end of the second week, as the young birds increasingly forage for themselves, and soon afterwards drive them out of the territory.

[49][50] The willie wagtail perches on low branches, fences, posts, and the like, watching for insects and other small invertebrates in the air or on the ground.

It will often hop along the ground and flit behind people and animals, such as cattle, sheep or horses, as they walk over grassed areas, to catch any creatures disturbed by their passing.

[9] It wags its tail in a horizontal fashion while foraging in this manner; the exact purpose of this behaviour is unknown but is thought to help flush out insects hidden in vegetation and hence make them easier to catch.

[51] The willie wagtail takes ticks from the skin of grazing animals such as cattle or pigs, even from lions asleep in a zoo.

[53] The adaptability and opportunistic diet of the willie wagtail have probably assisted it in adapting to human habitation; it eats a wide variety of arthropods, including butterflies, moths, flies, beetles, dragonflies, bugs, spiders, centipedes, and millipedes,[54] and has been recorded killing small lizards such as skinks and geckos in a study in Madang on Papua New Guinea's north coast.

[56] Aboriginal tribes in parts of southeastern Australia, such as the Ngarrindjeri of the Lower Murray River, and the Narrunga People of the Yorke Peninsula,[57] regard the willie wagtail as the bearer of bad news.

[56] It was thought that the willie wagtail could steal a person's secrets while lingering around camps eavesdropping, so women would be tight-lipped in the presence of the bird.

[2][3] The people of the Kimberley held a similar belief that it would inform the spirit of the recently departed if living relatives spoke badly of them.

[58] Its cleverness is also seen in a Tinputz tale of Bougainville Island, where Singsing Tongereng (Willie Wagtail) wins a contest among all birds to see who can fly the highest, by riding on the back of the eagle.

[2] The willie wagtail was held to have stolen fire and tried to extinguish it in the sea in a dreaming story of the Yindjibarndi people of the central and western Pilbara, and was able to send a strong wind if frightened.

[4] Called the kuritoro bird in New Guinea's eastern highlands, its appearance was significant in the mourning ceremony by a widow for her dead husband.

[63] The bird has been depicted on postage stamps in Palau and the Solomon Islands,[64] and has also appeared as a character in Australian children's literature, such as Dot and the Kangaroo (1899),[65] Blinky Bill Grows Up (1935),[66] and Willie Wagtail and Other Tales (1929).