460 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I50 



around eye dull black ; back of crown gray bordered with white ; 

 forehead, forecrown, lores, and lower hind neck white; rest of 

 upper surface light gray; primaries in fresh plumage with outer 

 webs silvery gray, which disappears with wear, leaving this area 

 black ; tail white to light gray centrally ; tip gray to dark gray ; under 

 surface white. 



Iris brown ; bill black, with yellowish tip ; tarsus and toes black. 



Measurements (from Ridgway, I.e., pp. 476-477). — Males, wing 

 259-302 (278.2), tail 122-130 (126.2), exposed culmen 52-54.5 

 (53.3), tarsus 25-27 (26) mm. 



Females, wing 270-294 (283.5), tail 99-121 (111.8), exposed cul- 

 men 49.5-53.0 (50.9) , tarsus 25-26 (25.5) mm. 



Fig. 71. — Head of Sandwich tern, gaviotin patinegro, Thalasseus sandvkensis 



acnflavidns. 



Migrant from the north. Fairly common along the Pacific coast 

 to the Gulf of Panama; recorded from Perme, San Bias, on the 

 Caribbean side ; found occasionally over Gatun Lake. 



This species is seen with fair regularity along the Pacific coast, 

 mainly in the Gulf of Panama. While most of the reports have been 

 in the months of northern winter, some nonbreeding individuals may 

 be found throughout the year. I shot one on June 11, 1953, op- 

 posite Isla Verde at the head of Golfo Montijo, and Imhof (Auk, 

 1950, p. 256) has recorded one July 31, 1942, on the coast of Code, 

 below Rio Hato, 



My notes include records of 2 near Isla Cebaco, March 20 and 

 29, 1962. On March 16 and 17, 1958, at Riomar, on the coast near 



