Spur-winged plovers (a.k.a. masked lapwings) are common around Melbourne. The birds are thriving even in my crowded and tatty part of town. I hear their calls every night as they fly down to the Maribyrnong River, which is only a couple of streets away. Their nagging kek-kek-kek-kek must one of the most familiar natural sounds of urban Victoria.
Southern birds differ in appearance from their northern cousins. In this part of Australia, plovers have a small yellow mask and black nape and lapels. Were it not for their tetchy attitude, you might even call them dapper. This form has spread to New Zealand and the Cook Islands.
Tropical birds sport a more extensive mask. They also lack the extra bits of black. This form also occurs in New Guinea, the Moluccas ... and Singapore. (See the link above for more information about distribution.)
The differences were initially considered sufficient to separate the forms into two species — Vanellus miles in the north and V. novaehollandiae in the south. Now they are recognised as subspecies with a broad overlap zone between Cairns and Mackay on the Queensland coast. Both forms occur here — alongside intermediates with variable masks and black markings.
Yes, nothing is ever really neat and tidy.
van Tets, GF, D'Andria, AH & Slater, E. (1967) Nesting distribution and nomenclature of Australian vanelline plovers. Emu 67: 85 – 93.