There are four subspecies of this bird; hartlaubii which breeds in South Africa, novaehollandiae which breeds in Australia, forsteri in the south–western Pacific from Torres Strait to New Caledonia, and scopulinus in New Zealand.
Red–billed gulls are highly gregarious birds which breed in large colonies of up to 5000 pairs on sandspits, boulderbanks, shellbanks, gravel beaches and rocky headlands, usually near marine upswellings. The birds start building nest sites in mid July but are not occupied until early August.