Chinese crested tern Thalasseus bernsteini

Critically endangered tern, long thought to breed solely on a few islands off the coast of China's Fujian province but recently noted breeding on islets off South Korea as well. Similar to Great Crested Tern (among which it nests) but smaller and paler, with darker outer primaries and dark cap that extends to the base of the orange-tipped bill. Much larger Great Crested has yellowish-green bill and white at bill base. Voice similar to Great Crested but higher in pitch.