The Gray-backed Tern breeds on tropical Pacific islands and often stays at sea outside the breeding season. Its full range is not well known.
Adults in breeding plumage have a grey back and brownish-grey wings. A black cap and a white stripe passing over the eye stand out.
It catches small fish and squid by plunge-diving or dipping at the surface. It sometimes feeds near tuna schools.
An extinction-risk assessment has not been added yet.