55 



69. Forster's Tern. Sterna Jorsleri. L, 15. (Forking of tail 4).' Closely resemb- 

 ling the Common Tern (see next species) in size and coloration. 



Distinctions. Forster's Tej-n lacks the dehcate 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 pm-e white underpaits 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. 



Distributioti. Western or interior bird. At one time it nested on the Detroit river, 

 but seems to have deserted that station and ndw 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 hir undo. 

 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 under parts 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 locahties 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 onty 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 

 sand}^ shores, scarcer on rock}^ 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 cry, harsh if taken by itself. 

 blends harmoniously into the soft surge of the surf and remains in keeping 

 with marine surroimdings. 



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 paradiscea. L, 15 -.50. 

 (Forking of tail 4 -50)1 Closely resembling the Common Tern (see above) in size and colour. 



Distinctions. The Arctic Tern has a little stronger greyish suffusion over breast and 

 imderparts 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 

 Roseate with which it can be confused, but the latter is too rare in Canadian waters to be 

 considered. 



'See footnote, p. 54. 



