454 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I50 



STERNA ANAETHETUS NELSONI Ridgway: Bridled Tern; 

 Gaviotina Monja 



Sterna anaetheta nelsoni Ridgway, U. S. Nat. Mus. Bull. 50, pt. 8, June 26, 

 1919, pp. 487 (in key), 514. (Zihuatanejo, Guerrero, Mexico.) 



In life, in general appearance like Sterna fuscata, but dark gray 

 on the back, and with a grayish white ring on the hindneck. 



Description. — Length, 375-400 mm. Adult, crown, hindneck, and 

 a heavy line through the lores to the eye deep black ; base of hind- 

 neck grayish white, forming a distinct collar; upper back, rump, 

 and upper tail coverts dark gray ; wing coverts, tertials, and middle 

 of back dark grayish brown; primaries, primary coverts, and second- 

 aries black; tail feathers white basally; outer pair with outer 

 web white and inner web dusky toward tip ; forehead, and sides of 

 crown back past the eyes, and under surface white, with the breast 

 and abdomen tinged strongly with pale gray. 



Immature, crown and upper hindneck dusky, with the feathers 

 bordered with plain gray ; back, rump, and upper tail coverts grayish 

 brown, barred indefinitely with grayish white; wings dusky, with 

 the coverts edged with grayish white; under surface white, tinged 

 very slightly with gray on the lower breast and abdomen. 



Iris brown ; bill, tarsi, and feet black. 



Measurements (from Ridgway, I.e., p. 514). — Males, wing 260-274 

 (267.7), tail 163-178 (170), exposed culmen 41.5-44.0 (42.0), tarsus 

 20.0-21.5 (20.7) mm. 



Females, wing 260-270 (265), tail 169-170 (169.5), exposed cul- 

 men 36.0-40.5 (38.2), tarsus 20 mm. 



Believed to nest on Los Frailes, off Punta Mala. 



The first record of this tern for Panama was an immature female 

 sent to me by Charles L. Fagan, wireless operator on the Grace Line 

 S.S. Santa Elisa, a bird that came aboard his ship at midnight on 

 September 24, 1922, when the ship was abeam of Punta Mala. To 

 date this is the only specimen recorded for Panamanian waters. 



On February 6, 1956, as the Air Force crash boat on which I 

 returned from Isla Coiba passed the two rocks of Frailes del Sur, 

 scores of terns appeared over the sea, with hundreds more over 

 the larger of the two islets. They continued in numbers near the 

 boat as far as Isla Iguana, and occasional individuals were noted 

 north nearly to Isla Otoque. A few that came near were identified 

 as the present species, but I believe now that part were Sterna fuscata 

 crissalis. None were seen when I had passed on the trip outward on 

 January 6, so that I believed that those observed on the return voy- 

 age had come in recently from the sea. 



