214 
SWIMMERS. 
north as the ever-inclement shores of Greenland and Spitz- 
bergen ; it is also found on the Arctic coasts of Siberia and 
Kamtschatka. In the winter it migrates to the Mediterranean, 
Madeira, and the Canary Islands. In .‘\raerica it breeds along 
all the coasts of the Northern and Middle States, and pene- 
trates north into the fur countries up to the 5 7th parallel of 
latitude. It also breeds on the sand-bars of the Great Western 
Lakes, being frequent in those of Erie, Huron, and Superior. 
In short, no bird is more common along the sea-coasts and 
lakes of the whole northern hemisphere, within the limits of 
cool or moderate temperature. 
These Terns arrive on the coast of New Jersey about the 
middle of April, and soon after they are seen on the shores 
of New England, where they are known by the name of the 
Mackerel Gull, appearing, with the approach of that fish, 
towards the places of their summer residence. In New York 
they are dignified, for the same reason, with the appellation 
of the Sheep’s-Head Gull, prognosticating also the arrival of 
that dainty fish in the waters of the State. About the middle 
of May, still gregarious as they arrive, they commence with 
the cares of reproduction. Artless in contrivance, the Terns 
remedy the defect of a nest by selecting for their eyries insula- 
ted sand-bars, wide beaches, but most commonly desolate, bare, 
and small rocky islets, difficult of access, and rarely visited by 
anything but themselves and birds of similar habits. A small 
hollow scratch on the surface of the shelving rock, with the aid 
of a little sand or gravel merely sufficient to prevent the eggs 
from rolling off, are all the preparations employed by these 
social and slovenly birds. The eggs are left e.xposed pur- 
posely to the warming influence of the sun, the parent sitting 
on them only in the night or during the existence of wet and 
stormy weather. They are about i % inches long 'oy in 
width, of a dull yellowish or pale whitish olive, with dark- 
brown blotches and spots, and others of a pale hue beneath 
the surface, the whole often disposed in a sort of irregular 
ring towards the obtuse end. Other eggs, again (as if of a dif- 
ferent species of bird), are spotted almost equally all over. 
