BIRDS. 
227 
Order 5. GAVI^. 
Family LARIDIE. 
Sub-family STERNINjFj. 
324. Sterna macrura, Naumann. Arctic Tern. 
Summer vi.sitant ; common along all the eastern seaboard, 
breeding in scattered colonies. Common at various points 
on the west and north coasts, usually in colonies, and pre- 
ferring insular positions. 
A common summer visitant all round the coast, breeding 
generally on the banks of a loch or river some distance 
from the sea. One favourite site is in the vicinity of a 
moorland loch about four miles from Wick, and the birds 
in passing to and fro from the sea always follow the course 
of the river (0. MSS., 1868). 
This species seems to us to outnumber the common tern. 
But on the Pentland Skerries perhaps the two are about 
equally common, occupying, however, different areas — the 
Arctic bulking on the eastern extremity of the main island, 
a few common terns associating with or flying amongst 
them, and the latter bulking most largely at the western 
side, a few of the Arctic terns associating with them. 
325. Sterna fluviatilis, Naumann. Common Tern. 
Summer visitant ; more usually breeding near fresh water than 
the Arctic tern. Breeds at Loch Migdale, near Bonar. 
We consider the Arctic tern the more abundant of the 
two species throughout the county, but we have ourselves 
taken eggs of the common tern on Loch Migdale. The 
statement that the common tern is found on a small island 
