50 BRITISH SEA BIRDS. 
COMMON TERN. 
This Tern, known as the Sterna hirundo of 
Linnzus, by most British ornithologists, although 
there can be little doubt that the great Swedish 
naturalist applied the term indiscriminately to this 
and the Arctic Tern, is one of the best known 
British species, especially round the English and 
Welsh coasts. It becomes rarer in Scotland, where 
it is largely replaced by the Arctic Tern. The 
Common Tern, distinguished by its white under- 
parts from the Arctic Tern, is migratory and 
arrives on the British coasts towards the end of 
April, retiring south in Autumn. Its favourite 
haunts during the summer are the various groups 
of low rocky islands, and the more secluded portions 
of the coast where sandbanks and shingle occur. 
Save on passage, this Tern is seldom seen far from 
the vicinity of its nest colony. The flight of the 
Common Tern is exceedingly buoyant and graceful, 
the long slender wings and acutely forked tail 
assisting greatly in the general effect. Like the 
Swallows the tarsus of the Terns is remarkably 
short, so that on the ground the birds seem awkward, 
and rarely attempt to walk far; on the sea, however, 
they are quite at home and swim well. ‘There are 
few prettier sights along the shore than a flock 
of Terns busy in quest of food. Where the beach 
is rocky, and the water somewhat deep inshore, the 
