FAMILY LARIDAE 441 



LARUS DELAWARENSIS Ord: Ring-biUed Gull; Gaviota de 

 Pico Anillado 



Larus Delawarensis Ord, in Guthrie, Geogr., 2d Amer. ed., 1815, p. 319. 

 (Delaware River, below Philadelphia.) 



A dark ring around the bill near the end ; legs yellowish ; smaller 

 than the herring gull. 



Description. — Length, 460 to 530 mm. Adult, back, scapulars, and 

 wings light gray ; body and tail otherwise white ; outer primaries black, 

 the two outermost tipped with white. 



In winter plumage, head and hindneck streaked with brownish gray. 



Immature, above grayish brown ; under parts white mottled with 

 grayish brown ; a narrow black subterminal tail bar. 



Measurements (from Ridgway, I.e., p. 625). — Males, wing 365-389 

 (378.1), tail 143-161 (150.8), culmen 42-45.5 (44.3), tarsus 54-61 

 (56.5) mm. 



Females, wing 334-372 (362.4), tail 132-150 (141.8), culmen Z7- 

 41.5 (39.5), tarsus 47-54 (50.9) mm. 



Migrant from the north. Casual wanderer. 



There is record of one banded as a nestling on Little Galloo Island 

 in Henderson Harbor, Lake Ontario, Jefferson County, N. Y., on 

 June 14, 1953, by Allan S. Klonick, that was found dead (without 

 feathers) at Boca del Rio Grande, Code, on July 11, 1954. Eugene 

 Eisenmann has reported ring-billed gulls seen along the sea wall in 

 Panama City, November 9 and 26 and December 4, 1962. 



The species comes south regularly along the coast of Mexico, and 

 has been reported from one sight record from El Salvador. It ap- 

 pears to be of casual occurrence in Panama. 



LARUS ARGENTATUS SMITHSONIANTJS Cones: Herring Gull; 

 Gaviota Argentea 



Larus Smithsonianus Coues, Proc. Acad. Nat. Sci. Philadelphia, vol. 14, no. 6, 

 June (Aug. 1), 1862, p. 296. (Eastern and western coasts of North America.) 



Adult with a subterminal spot of red on lower mandible; legs 

 flesh-colored ; larger than the ring-billed gull. 



Description. — Length, 560-625 mm. Adult, back, scapulars, and 

 wings pale gray ; head, neck, rump, tail, and entire underparts white ; 

 outermost primaries black with white toward the tips. 



Winter dress, head and hindneck streaked with dusky. 



Immature, mainly grayish brown, with head and neck streaked 

 with whitish ; rest of upper surface spotted irregularly with grayish 

 buff ; wings and tail blackish. 



