Sulphur Bay is a wildlife refuge home to several types of gulls, including black-billed gulls which are endangered in New Zealand. The gulls face problems from the high sulphur content in the warm water, which can damage their feet, and lack of fish due to the sulphur driving the fish away. Each spring the gulls make nests on the rocks around the edge of the bay out of plant materials like twigs and grass to lay their eggs.