166 



Nesting. On the ground; nest built of grasses. 



Distribution. North America, wintering in South America; in eastern Canada, along 

 the southern border breeding wherever found. 



The Bobolink in spring and summer is a bird frequenting hay and 

 clover fields. It can be seen any summer's day perched on the surrounding 

 fences or launching into the air on quivering wings, pouring forth its song 

 of ecstasy. Later in the season the rollicking male doffs his parti-coloured 

 gayness for the duller ochre and brown stripes of the female. His song is 

 replaced by metallic clinks, and with hundreds of others of this species 

 joined together in flocks he seek the marshes until autumn. On leaving 

 Canada for his winter home in South America he stops for a time in the rice 

 fields of the Carolinas and here he is hailed not as Bobolink, the merry 

 songster, beloved for both practical and sentimental reasons, but as the 

 obnoxious "Ricebird" that settles upon the crops in thousands and causes 

 decided damage. In the south he is shot in great numbers and sold for food. 



Economic Status. The Bobolink in Canada is an irreproachable bird 

 who charms us with his song and whose bad habits have yet to be discov- 

 ered. In May and June, 90 per cent of its food consists of injurious insects, 

 and 10 per cent of weed seeds with a few useful insects. In July and August 

 a very little grain is added. Yet this bird is regarded as a pest in the 

 southern States. 



Genus Molothrus. Cowbirds. 



495. Cowbird. cow BLACKBIRD. FR. L'ETOURNEAU ORDINAIRE. Molothrus ater. 

 L, 7-92. Plate XXVI A. 



Distinctions. A small Blackbird with a seal-black head and neck. The female is 

 ashy brown, lighter on throat, and can be distinguished from any of the Sparrows, which 

 she resembles in having a conical bill, by the even, unmarked coloration. 



Field Marks. Small Blackbird with short conical bill, a harsh rattling note, and 

 grating squeak. 



Nesting. Eggs laid in the nest of other, usually smaller species, on the ground or in 

 low situations. 



Distribution. Over most of North America. In Canada north to the limits of cultiva- 

 tion. Common except in the extreme coastal provinces of the east. 



The Cowbird is our only habitually parasitic bird. It never builds a 

 nest or incubates or cares for its young. In the absence of the 

 rightful owners it takes the opportunity of depositing one of its own 

 eggs in the unguarded nest of other birds. Usually the birds so imposed 

 upon accept the foreign egg without protest, at other times there are 

 strong objections 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 adapta- 

 tion is shown. The Cowbirds' egg usually hatches a few hours before 

 those of the original occupant of the nest and consequently the change- 

 ling 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 competitors 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 a 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 



