AMERICAN MAGPIE 135 



entering small traps ordinarily used for birds make it practically im- 

 possible to distinguish individuals in a natural group and then to keep 

 track of them for any considerable length of time. The screen of their 

 habitat further complicates any attempt to study this part of magpie 

 life. Repeated glimpses, however, result in a composite notion that 

 must approximate the true story. The most important items have come 

 from observers in Europe, but they seem to apply equally as well to the 

 American form. The available information indicates that many magpies 

 remain together in pairs through the year, and the changes consist mainly 

 in the replacement of lost mates and the entering of young birds into 

 the life of the flock. 



Aretas A. Saunders reports (MS.) that he saw birds going through 

 what he believed were courting actions, on March 12, 1911, in Montana. 

 Three he took to be males were following one supposed female. 



Nesting. — Nests of magpies are substantial structures that ordinarily 

 endure several seasons of weathering. They are so characteristic of 

 the species that they are useful as certain indicators of the nesting of 

 the birds in any locality where they may be foimd. In some instances 

 the nests remain long after the birds have given up nesting in a place 

 or have been driven out by human interference. 



Observers generally have agreed that only a single brood is reared 

 in a season. Bendire (1895) found that whenever a set of eggs was 

 destroyed a sec.ond and sometimes even a third set would be laid. These 

 were frequently in the same nest or in one close by. The second set 

 usually contained a smaller number of eggs, five or six. 



Many observers have concluded that a pair of magpies builds a whole 

 series of nests each season, of which they actually use only one. This 

 impression possibly resulted from the tendency of the birds to desert 

 a nest upon slight disturbance at an early stage of its construction. 

 Then, too, these conspicuous structures are more impressive than is the 

 case with smaller birds which may exhibit the same trait. 



Actual building in the Western States usually begins in March and 

 requires about six weeks. Before this for several weeks the birds show 

 indications of the coming nesting. Early stages are interrupted often 

 by late snows, but the birds ordinarily come back and resume their work 

 with the return of mild weather. A nest found in Washington by 

 Averill (1895) and started on March 22 had beginnings of a roof on 

 April 10 and held the first t^gg on May 1. In Colorado nests half 

 completed by the end of March contained partly incubated eggs on 

 April 28 (Oilman, 1907). 



Black-billed magpies nest in small colonies at sites separated and 

 strung out along some stream course or over some area of woodland 



