158 



nest. Uusally the birds so imposed upon accept the foreign egg without 

 protest, at other times there is strong objection and final resignation. 

 In a few cases, the nest is deserted or a new nest is built over the 

 offending egg, as is sometimes done by the Yellow Warbler. On incubation 

 an interesting case of adaptation is shown. The Cowbird's egg usually 

 hatches a few hours before those of the original occupant of the nest and 

 consequently the changeling is strong and well grown when the proper 

 occupants of the nest break their shell. It can monopolize the food, thus 

 increasing the difference in strength, and is able finally to hoist its compe- 

 titors from the nest to perish on the ground while it receives the attention 

 that should have been given to the whole brood. Thus practically every 

 Cowbird means the destruction of at least one brood of another species and 

 probably the Cowbird must be considered one of the greatest enemies of 

 the species imposed upon. Once the foster parents accept the intruding 

 egg they do not make any distinction between it and their own. The 

 Cowbird receives its name from its habit of following cattle, evidently 

 attracted by the flies and insects which gather about those animals. 



Economic Status. From a study of their food, Cowbirds would seem 

 to be purely useful birds. They consume large amounts of weed seeds and 

 harmful insects and only small quantities of grain or fruit, the former 

 largely waste and the latter wild. Their effect upon other equally useful 

 birds, however, puts a different complexion on their activities. Practically 

 every Cowbird raised to the fledgling stage means the elimination of a nest 

 full of other species. Perhaps the economic effects of the changelings equal 

 those of the individuals they displace, but the substitution cannot be looked 

 upon with equanimity. 



497. Yellow-headed Blackbird. FR. L'ETOURNEAU A TETE JATTNE. Xantho 

 cephalus tantkocephalus. L, 10. A Blackbird with white wing patches on the primaries, 

 and yellow head, neck, and breast. Female similar, but brownish rather than black; 

 brightness of yellow reduced, and white lacking on the wings. 



Distinctions. Above characterization unmistakable. 



Distribution. Western North America to northern parts of prairie provinces. 

 Only of accidental occurrence in eastern Canada. 



A marsh or swamp bird rare in eastern Canada. 



498. Red-winged Blackbird. SOLDIER BLACKBIRD. FR. L'ETOURNEAU A AILES 

 ROUGES. Agelaius phceniceus. L, 9-51. Plate XXVI B. 



Distinctions. All male plumages have at least suggestions of the red shoulders, though 

 sometimes they are reduced to scattered spots of orange. The female is always dis- 

 tinguishable from any other Blackbird by her sharply streaked coloration. 



Field Marks. The male is plainly characterized by its red shoulders, and the bird can 

 be recognized in all plumages by its characteristic notes, the most common one, only 

 uttered by the male, being well rendered into " O-ke-lee " or " O-ke-^ree " with a rising 

 inflection at the end. 



Nesting. In well made structure of rushes and grass tied 2 or 3 feet above the water 

 to reeds, cat-tails, or low bushes in swampy places. 



Distribution. As a species, the Red-wing is distributed over all of North America 

 north to the limit of trees. 



SUBSPECIES. The Red-wings are divided into a number of subspecies. The 

 common one in eastern Canada is the type form, the Eastern Red-wing. In the western 

 end of Ontario we probably get the Northern Red-wing A. p. arctolegus from the central 

 northern regions. It is characterized by somewhat larger size, but correct differentiation 

 can only be made by the expert. 



No marsh in eastern Canada is typical without one or more pairs of 

 Red-wings chasing each other or clinging to the cat-tails, themal es 



