54 
Subfamily—Sternine. Terns. 
General Description. 'The Terns, or Sea Swallows as they are sometimes called, are 
small gulls of a lighter and more graceful build and habit (see bill, Figure 5, p. 18). 
Distinctions. The bill, lighter, and more slender than that of the Gulls, and the forked 
tail are characteristic of the Terns and will usually separate them without difficulty. All 
Canadian species have a more or less forked tail and all but one in summer adult plumage 
have a sharply defined black cap. The forking of the tails of young birds, though beginning 
to show early in their development, does not reach its maximum until after they leave for 
the winter; hence through the summer and autumn many individuals will be seen with 
much smaller forks than the measurements indicate. 
Field Marks. The greater lightness of action on the wing and constant and rapid 
aerial evolution; the fact that Terns constantly dive from the wing, and the habit of 
commonly turning the bill straight down towards the water instead of carrying it on a line 
with the body are characteristic. The forked tails and black caps are also good recognition 
marks for adults. 
Nesting. Whereas Gulls seem to prefer rocky shores upon which to breed, the Terns, 
except Forster’s and the Black, favour sandy beaches, laying their eggs in a smooth circle 
of pebbles without other nest preparation. 
Distribution. As a subfamily, Terns are more southerly in distribution than Gulls, 
though at least one species, the Arctic Tern, has been found as far north as man has ever 
gone. All our species migrate, none remaining in eastern Canada through the winter. 
One has only to watch a flock of Terns feeding to recognize the appro- 
priateness of the popular term SeaSwallow. Their active grace and dainty, 
pearl-like colours are a joy to the nature lover. Terns are on the whole 
less marine in their habits than Gulls and are not as often seen far from land. 
They haunt harbours, shores, and beaches, and live largely upon small 
fish caught near the surface by quick sudden dives from the wing, but 
they are not scavengers. In these dives the birds plunge in head first with 
a splash of white spray in which for a moment they disappear, but unlike 
Gannets and Cormorants they never go far under water. 
64. Caspian Tern. FR.—LA STERNE CASPIENNE. LE GRAND ESTERLETTE. Sierna 
caspia. LL, 21. (Forking of tail 1-50)! The largest of our Canadian Terns. In colour 
very similar to the Common Tern (see p. 55). 
Distinctions. Large size of this Tern is characteristic. There are two other equally 
large species, but they are too rare to require more than passing mention here. The Cas- 
pian Tern is as large as some of the smaller Gulls; but its bill though comparatively 
heavy for a Tern is too graceful and tapering to be gull-like. 
ne Marks. Characteristic Tern coloration, and habit and size make the best field 
marks. 
Nesting. On sandy beaches, or rocky or gravelly islands. 
Distribution. A nearly cosmopolitan species. Found in the Old as well as the New 
World. Occurs rather irregularly all over Canada, but its known nesting stations are 
fou and scattered over the continent from lake Huron to Labrador and the gulf of St. 
awrence. 
The peculiarly disconnected and irregular distribution of this beau- 
tiful Tern suggests that it is a gradually disappearing species. This is 
greatly to be deplored as it is one of the most beautiful of our sea birds 
and it is to be hoped that careful conservation of its few remaining breeding 
stations will be inaugurated so that it will continue to adorn our waterways 
for generations to come. 
Economic Status. Though feeding largely upon fish, the size of its 
prey is limited to small fry. The rarity of the species precludes its doing 
any appreciable amount of damage. 
1This measurement shows the difference in length between the middle and outer tail feathers. A great part o 
the total length of these birds is in the greatly elongated outer tail feathers and these do not reach their maxim 
um 
in juvenile birds. Hence this figure is given to correct the oftentimes greatly misleading nature of the usual length 
measurement. i 
