BIRDS OF FERGUS COUNTY, MONTANA 47 



Distinguishing features: The male has forehead, stripe over eye, 

 sides of body and flanks orange yellow; other parts similar but with a 

 tinge of olive; wing prominently marked with black and white; female 

 lacks much of the bright coloring of the male; length 8-9 inches. 



510. BREWER'S BLACKBIRD. Scolecophagus cyanocephalus. 



This is our common blackbird, abundant everywhere in summer. 

 In 1899, the first Brewer's blackbirds appeared in Lewistown on April 29, 

 when a flock of ten or twelve spent the day in some aspens on Main 

 street. In 1900, the first were noticed on April 23; in 1901, the first black- 

 birds were seen on April 27; and in 1902, a solitary specimen on April 

 28 marked the opening of the season for Brewer's blackbird. Before the 

 regular nesting period, the blackbirds resort to the vacant feed-lots about 

 town and about the ranches. By the middle of May, however, they have 

 established themselves in the bushy tracts along the streams and irri- 

 gating ditches, ready to begin nidification. 



Brewer's blackbird nests in colonies, the size of the colony depend- 

 ing upon the extent of the bushy tract available. A clump of bushes ten 

 feet square may accommodate several pairs of birds. The nest is placed 

 about two feet from the ground, generally among upright stems. The first 

 nest of this blackbird which fell under my observation was nineteen 

 inches from the ground, in a crotch of a bush. The brim was twenty-four 

 inches from the ground, the nest cavity being four inches across and two 

 and one-half inches deep. There was an outer layer of coarse twigs, a mid- 

 dle layer of dried grass-stems plastered with mud, and a lining of rootlets 

 and horsehair. This nest contained five eggs of the blackbird and two 

 eggs of the cowbird, partially incubated on May 29. The eggs vary con- 

 siderably in color and markings, having a background of grayish or 

 greenish white, splashed and blotched with varying shades of brown. 



The site of the nest varies with the surroundings. Once I found 

 a nest of Brewer's blackbird in a crotch of a haw tree, seven feet from 

 the ground; and frequently the structure is made in the base of a bush, 

 on or near the ground. 



This blackbird is a very common victim of the cowbird in seeking 

 suitable foster-parents for its offspring. On June 4, 1901, I found a nest 

 of Brewer's blackbird, containing five eggs of the cowbird and two of the 

 owner. Indeed, it is unusual with me to find a nest of this species con- 

 taining a full complement of eggs without any of the cowbird's. On May 

 31, 1902, however, I found a nest of Brewer's blackbird in a bush in a 

 clump, which contained six eggs of the blackbird without any products of 

 the cowbird. 



By the first of August the blackbirds are forming into heavy flocks, 

 and thus they congregate on the ranches and feed-yards. Associated with 

 Brewer's blackbirds are red-winged blackbirds and cowbirds. The flocks 

 are largest about the end of August to the middle of September; there- 

 after the flocks gradually decrease in numbers until about the first of 

 November, after which the blackbirds are seldom seen except as belated 

 stragglers. 



