Until the last few decades, the Yellow Wagtail (Motacilla flava) was only known in Australia from a few records of apparent vagrants, the first recorded in 1905 at Duaringa on the Dawson River in eastern Queensland. The species has been observed consistently along the Northwest coast since then, trickling in small numbers there each summer from its breeding grounds in temperate and subarctic Eurasia and northern America, despite being uncommon and patchy there. Occasionally, birds stray further south from there.
The Yellow Wagtail call is a shrill, slurred tsweep, sometimes very brief trilling, tsip-tsip-tsipsi. It is common to see Yellow Wagtails in groups larger than 50 during migration and during winter quarters, but they are often seen as solitary in Australia. Australia seems to receive only the overflow from Indonesia’s main summering grounds. The birds arriving are polyglots of two or possibly three races that breed from southwestern Russia to Alaska. It is also known as Barnard’s Wagtail.
Their name comes from their gait, which is similar to that of pipits, but longer and trimmer in wings and tails, and more colorful. Their heads nod forward and back, while their tails teeter constantly up and down as they walk briskly with long steps.
Their food consists of insects, larvae, spiders, and occasionally mollusks and worms. They pick them up as they go, often in short dashes or flutters. When not feeding the birds spend much time preening, either on the ground or perching on a bare tree or stump. When they take flight, they typically chirrup as long as they are flushed. Their flight is graceful and undulating, in long curves with closed wings; if flushed, they often flutter. At night they roost on the ground, often in flocks at non-breeding quarters, among grass and herbage, or in reed beds.
In Australia, Yellow Wagtails are frequently found near open wetlands, foraging along the bare shores of freshwater swamps, crops, and bare bore drains, as well as over short-grassed fields and even rocky coasts. On their Eurasian breeding grounds, they keep to similarly damp areas near water, from sea level to 1000 meters or more altitude. Males fluff their plumage, draw in their heads, sing, and shiver their wings on display. This is whether around the female on the ground or hovering over her in midair, with her tail fanned down. She undertakes most of the nest-building and incubation, but both parents feed and care for the young and often rear two broods in a season.
Yellow Wagtails are about 160-190 mm long. As far as identification is concerned, both sexes are similar; the male is larger; the female is browner-headed, and the duller creamier-yellow ventrally in all plumages. Breeding male citrine-green over upperparts, and wings dusky with yellow-white feather edging. The tail is dusky with the outermost feathers white. The head is citrine to grey with yellow to white eyebrows and malar stripe according to race. Underparts from the throat to the undertail are rich yellow. Their eyes are dark brown. Bill and feet are grey-black. Non-breeding males have duller browner citrine or greyer overhead and back; eyebrows paler and yellower; underparts paler, becoming whitish. The immature bird’s upper parts are brown; underparts are white and washed buff; brown lines down the sides of the chin. It is closely related to Citrine Wagtail.
Nesting and breeding occur in Eurasia from June-July. Nest a cup of plant fibers, mammal hair, and sometimes moss, in a depression in the ground, often in thick vegetarian. Eggs: usually five or six; ochre, sometimes mottled or with thin dark streaks; oval, about 1 9 x 14 mm. The incubation period is about 14-15 days, mostly female. The young bird fledges in about two weeks. Yellow Wagtail breeds in Northern Hemisphere June-July and migrates south. There are approximately 18 races; however only two, possibly three reaching Australia.