75 
Tern, Arctic. — This bird is not to be distinguished from the 
Common Tern save by the expert, and, indeed, it takes a very exact 
knowledge for even the student to determine between the Common 
and Arctic Tern. The latter is very slightly smaller in size, being, 
perhaps, only half an inch less in length, but in general colour, 
appearance, and habit it in no way differs from its congener. The 
one infallible test lies in the difference of the length of the tarsus, 
which in the Arctic Tern is longer than in the Common Tern. 
The Arctic Tern is the only species found nesting in the Shet- 
lands, where it breeds in large colonies on some of the out lying 
skerries. Further south it is not uncommon to find colonies of both 
Arctic and Common Tern breeding in close proximity. Generally 
speaking, those nests nearest the actual shore belong to the Arctic, 
the Common Tern not infrequently occupying a site farther from 
the sea, often in swampy parts or amongst the sandy dunes. 
The eggs of the Arctic Tern are two in number, very seldom three, 
and resemble closely those of the Common Tern, though, if distinc- 
tion can be made, they are possibly a trifle smaller and more boldly 
marked, though the eggs of each species run through so many 
variations as to quite overlap each other in this regard. The Arctic 
Tern is, like the Common Terri, a bird of very powerful flight, 
which it can sustain hour after hour unweariedly. It also is a 
summer visitant to our shores, and during the winter season dis- 
tributes itself along the shores of Africa and further east. 
Tern, Common. — This species is a summer migrant to our 
shores, along which it is widely distributed. It does not extend to 
the Shetlands and in the Orkneys and the extreme north of Scotland 
it is outnumbered by the Arctic Tern, but it is the more numerous 
along the southern parts of the Scottish coast and on the coasts of 
England. 
The Common Tern is an elegant bird in regard to shape, and its 
plumage is delicately coloured. It is known as the Sea Swallow, 
and owes this name to its resemblance in shape to the latter bird. 
It is, however, much larger, being some 15 inches in length, and in 
colour it is above of pearly grey, the head being capped with black, 
bill and feet of brilliant blood red, and it is only owing to the length 
of the wing and the long forked tail that any resemblance can be 
traced entitling it to the name of Sea Swallow. The Tern in its manner 
of obtaining food comes between the diving sea fowl, such as the 
Gannet, and the surface feeders, such as the Gulls. It feeds chiefly 
on the fry of fish, and in pursuit of these passes with hovering flight 
along the shore, its head downturned with beak at right angles to 
its breast, every now and again darting from above and striking the 
water in a cloud of spray, but it at no time appears to descend more 
than a few inches below the surface. The Common Tern breeds in 
colonies, always near water and usually on the sea coast, a favourite 
site being a low-lying islet. Occasionally these colonies are very 
large, the nests usually placed in such close proximity as to make it 
difficult for a visitor to avoid stepping on the eggs, while the ear is 
assailed by the ceaseless cry, resembling k-rr, shrill and long drawn 
out, of the birds disturbed from their nests. The intrusion is 
vehemently resented by many a downward swoop towards the 
visitor’s head. These birds seem to get along with little sleep, as a 
visit to their nesting place at any hour of day or night reveals the 
same restless clamour. The nest of the Common Tern is placed 
upon the ground. The eggs are two or three, frequently three, in 
number, and are of a stone or olive ground colour, spotted with 
black, with fainter under shell markings of a purplish tinge. 
