278 THE COMMON TERN : . 
THE ARCTIC TERN 
STERNA MACRURA 
Bill slender, red throughout; under plumage ash-grey; tail much forked, 
longer than the wings; legs orange-red, in other respects very like the 
last. Length fifteen inches. Eggs as in the last. 
Tuis bird, as its name indicates, frequents high northern latitudes! 
to which, however, it is not confined; since in the Orkneys and 
Hebrides it is the common species. It breeds also on the coast 
of some of the northern English counties, but not farther south 
than the Humber, though several instances are recorded of large 
flocks making their appearance in different places at the season 
when they were probably on their way from their winter quarters 
—far away to the south—to their breeding-ground. In the 
rocky islands, which they frequent from May to September, they 
form colonies and lay their eggs, generally apart from the allied 
species. The eggs closely resemble those of the Common Tern, 
but are somewhat smaller. In its habits and general appearance 
the Arctic Tern comes so close to the last-named species, that 
the birds, even when flying together, can only be digdiggushed by 
the most practised eye. 
THE COMMON TERN 
STERNA FLUVIATILIS 
Bill moderate, red with a black tip ; head and long feathers on the back of the 
head black; upper parts bluish ash; quills ash-grey, brown at the tips; 
tail much forked, not longer than the wings, white, the two outer fea- 
thers on each side dusky on the outer webs; under parts white, tinged 
with grey on the breast ; irides reddish brown; feet coral-red. Young 
birds have a good deal of white about the head, and the feathers on the 
back are tipped with white; tail ash-grey, whitish at the tip. Length 
fourteen inches. Eggs olive-brown, blotched and spotted with ash and 
dusky. 
On those parts of the coast where the Common Tern is abundant, 
no sea-bird is more likely to attract the notice of the visitor than 
the Common Tern. It is less in size than any of the common species 
of Gull, with which, however, it is often confounded by the unob- 
servant. It is more lively and active in its motions, not ordinarily 
flying in circles, but, if I may use the expression, ‘ rambling ’ 
through the air, frequently diverging to the right or left, and raising 
or depressing itself at frequent intervals. These characters alone 
are sufficient to distinguish the Tern from any of the Gulls; 
but it presents yet more striking features. Its tail is elongated 
and forked like that of the Swallow, and from this character 
rather than from its flight it is commonly known as the Sea 
Swallow. Its mode of taking its prey is totally different from 
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