AECTIC TERN 393 



scapulars, and wing-coverts, barred and mottled with ash- 

 brown ; outer web of tail-feathers, grey ; inner web, white ; 

 breast and abdomen, milk-white. 



BEAK. Orange-red with brownish-black tip. 



BEAK. (Immature Bird.) Reddish-yellow with dark 

 brown tips (cf. Arctic Tern). 



FEET. Deep red. 



IRIDES. Blackish-brown. 



AVERAGE MEASUREMENTS. 



TOTAL LENGTH 14'25 in. 



WING 10-5 



BEAK 1*7 ,, 



TARSO-METATARSUS ... ... 0*85 ,, 



EGG ... 1'7 X I'l in. 



ARCTIC TERN. Sterna macrura (Naumann). 



Coloured Figures. Gould, ' Birds of Great Britain,' vol. v, pi. 

 72; Dresser, 'Birds of Europe,' vol. viii, pi. 579; Lilford. 

 * Coloured Figures,' \ 7 ol. vi, pi. 9. 



In its habits and plumage this greatly resembles the 

 preceding species, though differing considerably in dis- 

 tribution over the British Isles. The northern range of 

 the Common Tern overlaps that of the Arctic ; this is 

 well seen about the latitude of the Northumberland and 

 Lancashire coasts, where, as on the Fame and Walney 1 

 Islands, both species freely breed in company. 



Proceeding southward, this species diminishes 2 as the 

 Common Tern increases ; northward, the Arctic predomi- 

 nates ; above the latitude of the Moray Firth and the Island 

 of Skye the Common Tern is much reduced in numbers. 



1 On Walney Island, the Common Tern appears to be the more 

 numerous species. 



2 Small numbers of Arctic Terns are to be found breeding as far 

 south as the Scilly Isles. 



