55 
69. Forster’s Tern. Sterna forsteri. L,15. (Forking of tail 4).! Closely resemb- 
ling the Common Tern (see next species) in size and coloration. 
Distinctions. Forster’s Tern lacks the delicate grey shading on the flanks and under- 
parts characteristic of the Common Tern, and the outer feathers of the tail have the dark 
web on the inside instead of the outside of the shaft. 
Field Marks. The pure white underparts are the most reliable field guides. The 
species is, however, so rare east of lake Huron that its identification in life should be based 
only on birds in the hand. 
Nesting. On slight elevations in grassy marshes, in nests built of fragments of waste 
vegetation. 
Distribution. Western or interior bird. At one time it nested on the Detroit river, 
but seems to have deserted that station and now as a breeder must be sought for farther west. 
These Terns frequent marshes rather than beaches and do not usually 
gather in flocks like the Common Tern. They should be looked for as 
individuals in flocks of other species. 
Economic Status. Though fish eaters, their size and usual habitat 
prevent their being harmful. 
70. Common Tern. WILSON’S TERN. FR.—LA STERNE COMMUNE. Sterna hirundo. 
L, 15. (Forking of tail, 3-0 ).! Plate II B. . 
Distinctions. The dark, outer, instead of inner, webs on the outer, long tail feathers 
and delicate greyish,, instead of pure white, breast and underparts distinguish the com- 
mon from Forster’s Tern. The grey of breast and underparts is rather less pronounced 
than in the Arctic Tern and the legs and feet are decidedly larger and heavier. The bill is 
usually dark in colour towards the tip, whereas that of the Arctic is evenly red. Juveniles 
are more or less washed with brownish above and have blackish bills. With adults in winter, 
the black cap is replaced by a more or less broken dark cape over hind head and upper 
hind neck. In this plumage Forster’s Tern has a broad black streak across the eye. 
Field Marks. Except in the few localities where other Terns are known to occur 
commonly it is always safe to conclude that this is the species seen. The pearly-grey 
underparts will usually distinguish it from Forster’s Tern, but it is difficult to separate it 
from the Arctic Tern which, however, is only to be expected on our extreme eastern sea 
coast. 
Nesting. Depression in sand on beach. 
Distribution. A circumpolar species migrating to South America and Africa. More 
or less common all over Canada and breeding in favourable localities throughout its Cana- 
dian range. 
This is the most abundant Tern of eastern Canada. Common about 
sandy shores, scarcer on rocky shores, it may be seen on any of our larger 
bodies of water, salt or fresh, throughout the summer. Its wonderful 
lightness of wing, graceful circlings, one instant hovering on rapidly beating 
wings stationary in the air as it regards some coveted prey below and 
the next dropping like a plummet with a sparkling splash, are constant 
delights to a seeker of the beautiful. Its shrill ery, harsh if taken by itself, 
blends harmoniously into the soft surge of the surf and remains in keeping 
with marine surroundings. 
Economic Status. Though fairly numerous in suitable localities this 
species is too small to be seriously destructive. 
71. Arctic Tern. FR—LA STERNE ARCTIQUE. Sterna paradisea. L, 15-50. 
(Forking of tail 4-50)! Closely resembling the Common Tern (see above) in size and colour. 
Distinctions. The Arctic Tern has a little stronger greyish suffusion over breast and 
underparts than the Common Tern. Bill is red to tip and feet and legs are very small and 
weak. Its range separates it from Forster’s Tern and there is only the Common and the 
er ou which it can be confused, but the latter is too rare in Canadian waters to be 
considered. 
1See footnote, p. 54. 
