TERNS 
239 
Economic Status. Though probably a fish feeder and the largest of its 
subfamily the Caspian Tern is too scarce and its food is too small to have 
any appreciable economic influence. 
A particularly beautiful and interesting bird. Its wide range, scat- 
tered breeding stations, and growing scarcity suggest that the numbers we 
see today are the remnants of a once much more numerous and generally 
distributed race and that if we are to have it with us in the future special 
care should be taken to guard its local nesting communities from molesta- 
tion. 
77. Black Tern, la stern e noire. Chlulonias nigra. L, 10 (Forking of tail O S). 
The smallest of our common terns, dark slate-grey, deepening to dull black on head, neck, 
and underparts. 
Distinctions. The above description is 
sufficient to separate summer adults. 
\\ inter and immature birds have a dirty 
white face, throat, neck ring, and under- 
parts, and the grey above is suffused with 
more or less brown. It is, however, always 
considerably darker than corresponding 
plumages of other species. This fact, and 
the small size of the bird, should be suffici- 
ent to differentiate it at all times. Im- 
mature plumages retained throughout the 
following summer have been the basis of 
occasional records for the White-winged 
Black Tern, which has been removed from 
the Canadian list. 
Field Marks. Size and coloration make 
this species easy to recognize in life. 
Nesting. On slight elevations such as 
old muskrat houses or floating debris in wet marshes, nest of vegetable matter. 
Distribution. The American Black Tern is a bird of the interior, breeding from the 
Great Lakes region westward, north as far as Great Slave Lake in the interior, and in south- 
ern British Columbia. 
SUBSPECIES. The Black Tern occurs in both Europe and America in allied sub- 
specific forms of which the European is the type. The American Black Tern (la Sterne 
noire d’Am6rique) C.n. surinamensis is the subspecies with which we are concerned. 
This is a bird characteristic of the inland marshes, only rarely seen on 
the larger bodies of water. In southern Ontario and throughout the 
interior prairies no extensive expanse of watery marsh is without it. Its 
general habits are much like those of the other terns. It is less common 
in British Columbia than east of the mountains. 
Economic Status. The insect content of this bird’s food is probably 
larger than that of the other terns. In the south it is known to consume 
the larvae of the cotton-boll weevil and it follows the ploughman of the 
west for the grubs turned up. Therefore, we may venture to state that it is 
probably actively beneficial. At any rate the fish it takes, if any, are mud- 
inhabiting forms of small economic importance. 
Figure 350 
Black Tern; scale, R 
Winter Spring 
76910 16} 
