56 



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. 



69. Forster's Tern. ph. — la sternb db fobster. Sterna forsteri. L, 15. (Forking 

 of tail 4.) 1 Closely resembling 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 

 voice, hoarser and deeper than that of the Common Tern can always be recognized after 

 having once been heard. The species is 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 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. pr. — la sterne commune. Sterna hirundo. 

 L, 15. (Forking of tail, 3.) 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. Its call is also recognizably distinct (See previous species). 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 hindhead and upper hindneck. In this plumage 

 Forster's Tern has a broad black streak through 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 may sometimes, and its shriller voice will always 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 ones, it may be seen on any of our larger 

 bodies of water, salt or fresh, throughout the summer. Its wonderful 

 lightness of wing, and 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 cry, 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. 



1 See footnote, p. 55. 



