Birds  Wild birds (frequently found in waterfowls and shorebirds)  H1–H16 and N1–N9HP: H5NX, X = NA subtypes  No or mild diseaseHP: isolated from dead wild birds  HA  TerminalNeu5Acα2,3GalSome gull/tern H16: α2,6Neu5Ac ≥ α2,3Neu5AcInternalDuck type: non-fucosylate, SiaLec, 3′SLNGull type: fucosylated, SiaLex and 6-sulfo-SiaLex Gull/tern H16: 6′SLDN ≥ LSTb, but some 6-sulfo-SiaLex > 6′SLDN, LSTb  [23,24]