These are found on the coast and islands of most of Australia but are more common on the Queensland coast and Great Barrier Reef than elsewhere, they are now rare on Victorian and Tasmanian coasts. They are also found in the oceanic region of India, Southeast Asia, Japan, Polynesia and New Zealand.
There are two colour forms; a white form that has a white body and wings and a dark form that has a slate-grey body and wings as in the photo.
They are found on beaches, rocky shores, tidal rivers and inlets, mangroves, and exposed coral reefs, the photo was taken at the public wharf in Rosslyn Bay where there are often a number of seabirds.
Their diet is small fish, crustaceans, molluscs and insects, they hunt their prey by crouching low as they move through shallow water or over rocks and coral.
Males and females are identical and breed throughout the year. A stick nest platform lined with seaweed is built in trees or on the ground under shrubs or rock ledges. Both sexes incubate the eggs and the young, which remain in the nest for up to 6 weeks.