"Immature.--Like that of fluviatilis [= hirundo] from which it can hardly be distinguished except by the color of the bill and feet and the somewhat smaller size and more delicate shape of the latter." (Saunders.) 80. STERNA BOREOTIS (Bangs). NORTHERN BERGIUS TERN. Sterna bergii Saunders, Cat. Birds Brit. Mus. (1896), 25, 89 (part); Sharpe, Hand-List (1899), 1, 136 (part). Sterna bergii boreotis Bangs, Bull. Mus. Comp. Zool. (1901), 36, 256. Sterna boreotis McGregor and Worcester, Hand-List (1906), 20. Ga-bi-o'-ta, general name for gulls and terns. Agutaya (McGregor); Balabac (Steere); Bantayan (McGregor); Bohol (Everett, McGregor); Calamianes (Bourns & Worcester); Caluya (Porter); Cebu (Bourns & Worcester, McGregor); Cuyo (McGregor); Guimaras (Bourns & Worcester); Leyte (Everett); Luzon (Bourns & Worcester); Masbate (Bourns & Worcester); Mindanao (Murray, Koch & Schadenberg, Steere Exp., Bourns & Worcester); Mindoro (Porter); Negros (Bourns & Worcester, Keay); Palawan (Whitehead, Platen, Bourns & Worcester, White); Panay (Bourns & Worcester); Pata (Mearns); Romblon (Bourns & Worcester, McGregor); Samar (Bourns & Worcester); Sibuyan (Bourns & Worcester); Siquijor (Bourns & Worcester, Celestino); Sulu (Bourns & Worcester); Tablas (Bourns & Worcester); Tawi Tawi (Bourns & Worcester). Liu Kiu Islands and Northern China Sea. "Adult male in full breeding plumage (type).--Forehead, cheeks, lores, ear-coverts, neck all round, and whole under parts, including lining of wing and bend of wing, pure white; crown and long occipital crest glossy black; mantle, wings, rump, upper tail-coverts, and upper surface of middle rectrices dark smoke-gray, darkest on wings and middle of back, where the color is almost mouse-gray; primary quills white; first primary with outer web, a band along quill on inner web and tip blackish, with a silvery suffusion which is most marked toward center of feather; broad outer margin of inner web, below the black tip, white; second primary similar but black tip deeper in color and extending a short distance down outer margin of inner web, thus inclosing the white of inner web for a short distance; third, fourth, and fifth primaries like second, but black tip gradually growing deeper in color; outer rectrices above pale smoke-gray at tips and along shafts, pale grayish white toward base; second and third rectrices darker on the outer webs and at tip and whitish toward base of inner webs. Bill in dried specimen, dull yellow clouded with olive toward base; feet and tarsi blackish. Wing, 344; tail, 178; tarsus, 28; culmen, 62." (Bangs.) "Very common throughout the group, especially abundant about the native fish-pens." (Bourns and Worcester MS.) This is much the largest tern found in the Philippines. Rather local in its distribution but usually found not far from fish-corrals or where schools of small fishes appear near the surface of the water.