643 



STERNA ARCTICA. THE ARCTIC TERN. 



Hirondelle-de-mer arctique. Sterna arctica. Temm. Man. d'Orn. II. 742. 

 Arctic Tem. Sterna arctica. Selby, lUustr. Brit. Ornith. II. 473. 

 Sterna arctica. Jenyns, Brit. Vert. Anim. 

 Sterna arctica. Bonap. Comp. List, 61. 



Bill about the length of the head, slender, vermilion ; feet 

 crimson; tarsus about six-twelfths long; tail about half an 

 inch longer than the wings. Upper part of the head and 

 nape deep black ; general colour of the plumage pale bluish- 

 grey ; upper and loiver tail-coverts white. 



It is not difficult to distinguish this species from the 

 Common Tern, though they were formerly confounded, and 

 at a httle distance seem identicaL The hluish colour of the 

 lower parts, the much shorter tarsus, the greater extent of 

 the tail beyond the wings, and the uniform deep red tint of 

 the bill, though the tip is sometimes more or less dusky, are 

 easily-observed characteristics. 



Male in Summer. — The general aspect and proportions 

 are those of the Common Tern. The bill is about the same 

 length as the head, slightly arched, slender, compressed, 

 tapering, very acute. Upper mandible with the dorsal line 

 gently arcuato-declinate, the ridge narrowed towards the 

 end, the sides convex, the edges sharp and inflexed, the tip 

 very acute. Nostrils linear, parallel, basal, pervious, the 

 nasal groove extending beyond them nearly to the tip. Lower 

 mandible with the angle extremely narrow, the junction of 

 the crura mesial, little prominent, the sides erect and slightly 

 convex, the edges sharp and inflexed, the tip extremely 

 acute. 



The eyes rather small, as are the apertures of the ears. 



