The Variable Oystercatcher is endemic to New Zealand. Plumage can be completely black, mottled with white on chest or similar to Pied form (but some differences in shape and where the white bits start). On Stewart Island the plumage of the "Variable" doesn't vary -- it is, as New Zealand rugby players, all black. The eye, beak and legs on adults is red. Juveniles have pinkish legs and brown eyes.
Variable Oystercatcher with chicks
South Island Pied Oystercatcher
The South Island Pied Oystercatcher of New Zealand has similar plumage to the Pied Oystercatcher of Australia
(Haematopus longirostris), but the border of white with black on the back is a different shape. It also has a longer red bill and shorter red legs. Both look similar to the Eurasian or Common Pied Oystercatcher
(Haematopus ostralegus) prevalent in northern Europe.
The adult has a red eye, bill and red legs; the juvenile has a brown eye, paler bill and pinkish legs.
They gather in small flocks when not breeding.