22 BIRDS OF PENNSYLVANIA. 



Sterna antillarum (LESS.). 



Least Tern. 



DESCRIPTION (Plate 58). 



Adult, in spring. Length about 9 inches ; extent about 20 inches. Bill yellow, 

 with black tip ; legs yellow, claws black ; iris brown ; a triangular white spot on 

 forehead, extending to eye ; narrow black line extending from base of upper man- 

 dible is continuous with the black of crown and region about back of head ; back, 

 wings, rump and tail light grayish-blue; two or three outer primaries black on 

 upper surface ; narrow line about base of bill above sides of head, neck and entire 

 under parts white. 



Young, in August. Bill (dried skin) blackish-brown ; lower mandible towards 

 the base and inside of mouth yellowish-brown ; tarsi yellowish ; iris brown ; fore- 

 head dirty brownish- white ; crown and upper parts generally mottled with brown ; 

 upper part of wings mostly dark slate color ; primaries darker than in old bird ; 

 under plumage white. 



Habitat. Northern South America, northward to California and New England, 

 and casually to Labrador, breeding nearly throughout its range. 



This handsome and graceful little bird is the smallest of the Terns. 

 Fishermen on the coast of New Jersey, where the Least Tern is a com- 

 mon summer resident, know it by the names of "Sea Swallow," "Little 

 Gull " and "Striker." During- migrations, particularly in the latter part 

 of August and September, Least Terns are not infrequently met with 

 in Pennsylvania, especially in the southeastern section. I have seen 

 seven of these Terns taken one in the spring, the others in August and 

 September in the counties of Chester, Lancaster, Montgomery and 

 Delaware in the past ten years. Hon. Gerard C. Brown, of Yorkana, 

 has observed it in York county as a straggler. Dr. John W. Detwiller, 

 of Bethlehem, shot one on the Lehigh river, in the fall, and in Berks 

 county Mr. D. Frank Keller says it is an accidental visitor. According 

 to Prof. J. B. Bobertson, of Franklin, a straggler was once taken in Ven- 

 ango county. In the summer of 1883, at Brigantine, New Jersey, where 

 the Least Terns were then breeding in considerable numbers, laying 

 their eggs in slight depressions in the dry sand and among- the shells 

 on the sandhills along the beach, I obtained the bodies of over seventy- 

 five of these Terns from two taxidermists who were collecting the skins 

 for New York and Philadelphia dealers to be us6d for ladies' hats. An 

 examination of these birds all killed in one day showed that they had 

 fed almost exclusively on little fish ; not more than four or five had any 

 traces of insects in their stomachs. 



Sterna fuliginosa GMEL. 



Sooty Tern. 



DESCRIPTION. 



Adult. Length about 17 inches ; extent about 34 inches. Bill and legs black ; iris 

 reddish-brown ; forehead, sides of head and entire under parts white ; back, wings 

 and upper parts deep black. 



In the young the plumage is sooty-brown, darkest on back and wings, grayish on 

 abdomen ; lining of wings white ; scapulars and wing coverts tipped with white. 



