440 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL, I50 



14. Back brownish gray ; with hindneck white to pale gray. 



Bridled tern, Sterna anaethetus nelsoni, p. 454 

 Back and hindneck black Sooty tern, Sterna fuscata, p. 455 



15. Bill black, with yellow or whitish tip; smaller, wing less than 310 mm. 



Sandwich tern, Thala^seus sandvicensis acufiavidus, p. 459 

 Bill orange or red ; wing more than 350 mm 16 



16. Bill orange to orange-yellow ; feathers on back of head more elongated and 



definitely pointed; tail forked for one-fourth of its length; smaller, wing 



less than 400 mm Royal tern, Thalaseus maximtis maximns, p. 458 



Bill red; feathers on back of head less elongated, more rounded at tip, 

 and blended in a smooth crest ; tail less deeply forked ; larger, wing more 

 than 400 mm Caspian tern, Hydroprogne caspia, p. 451 



LARUS MODESTUS Tschudi: Gray Gull; Gaviota Garuma 



Larus modestus Tschudi, Arch. Naturg. vol. 9, pt. 1, 1843, p. 389. (Lurin, south 

 of Lima, Peru.) 



Slightly larger than the laughing gull ; body uniform gray, with a 

 prominent white border on the posterior edge of the wing. 



Description. — Length, 420 to 450 mm. Plain gray ; anterior half of 

 crown, forehead, and throat grayish white ; primaries and secondaries 

 black, with the inner primaries lightly, and the secondaries broadly, 

 tipped with white ; tail with a subterminal band of black, and a 

 narrow tip of white. 



Iris brown ; bill black ; tarsus and toes black. 



Measurements (from Murphy, Oceanic Birds S. Amer., 1936, p. 

 1049).— Males, wing 314-337 (329.2); tail 117-131 (124), culmen 

 40-43 (41.8), tarsus 48-55 (53.2) mm. 



Females, wing 299-328 (318.7), tail 116-122 (119.6), culmen 37-41 

 (39.6) , tarsus 46-51 (48.7) mm. 



Visitor from the south. Casual in the Gulf of Panama. 



According to Eisenmann (Trans. Linn. Soc. New York, vol. 7, 

 1955, p. 32), Robert Cushman Murphy has reported this species in 

 Panama Bay near the entrance to the Canal. On February 6, 1956, 

 on the return from Isla Coiba, about 5 kilometers south of Isla 

 Otoque, I saw 3 grayish gulls, lighter on forepart of the head and 

 with a conspicuous white border on the posterior edge of the wing. 

 It is not always easy to identify birds flying at a distance from the 

 deck of a crash boat travelling at rapid speed, and at the time I 

 thought that they were Heermann's gulls, Larus heermanni, from 

 the north, and so recorded them (Smithsonian Misc. Coll., vol. 134, 

 no, 9, 1957, p. 33). I believe, however, that it is more probable that 

 they were Larus modestus, a species that ranges regularly to central 

 Ecuador and has been reported casually along the Pacific coast of 

 Colombia. 



