シロビタイアジサシ Sterna striata

Medium-sized tern with pale gray coloring on upperparts and white on neck and underparts. Has black cap and long pointed black bill which are separated by a white band. Tail is long and quite forked. Cap in non-breeding birds is reduced above the eye, creating a white forehead. Juveniles are similar to adults in non-breeding plumage but have light brown mottling over their back. Common along coastlines around New Zealand, sometimes in very large flocks. Immature birds can disperse in winter to southeastern Australia. Arctic Tern and Common Tern are similar, but rarely seen in New Zealand; White-fronted Tern is larger and has lighter plumage.