One of the largest of the frigatebirds; females are larger than males. Adults are easier to separate from similar frigatebirds than younger birds. Adult males are all black with a white oval belly patch and white spurs emanating outwards from the body onto the wing. Adult females have a black throat with a white hind collar, breast, and belly. The white spurs on the wing are angled forwards. Juvenile and immature plumages are variable and are best separated from other frigatebirds by size when comparison is possible. Breeding restricted to Christmas Island and usually silent unless breeding. Stragglers appear far away from the breeding colony in parts of Indian and Eastern Pacific Oceans.