136 BULLETIN 191, UNITED STATES NATIONAL MUSEUM 



or thicket. Such a group of nests may occupy an area half a mile across 

 or a line a mile or more in length. Kalmbach (1927) found 26 broods 

 of young within a mile along a creek in Utah. Each group of nesting 

 pairs is separated from the next group, often by an intervening area 

 of unfavorable habitat, but sometimes the vacant places result merely 

 from lack of birds to fill them. At any rate the favorable habitat is 

 seldom filled and the nesting pairs tend to be clustered rather than 

 spread evenly. 



The nest of the magpie is noteworthy for the large quantity of material 

 contained in it. Ordinarily the structure measures about 2 feet in 

 height by 1 foot in diameter, or slightly larger. A nest found by Sillo- 

 way (1903) in Montana was 4 feet high, 4 feet long, and 40 inches wide. 

 Dawson (1909) found one in Washington 7 feet from bottom to top, 

 the upper one-third being the dome, and another not over a foot in 

 diameter and scarcely that in depth. 



The base and outer walls of a nest are composed of coarse material, 

 heavy sticks, often thorny ones. The materials vary greatly, depending 

 mainly upon the nature of the available supply. The sticks may be 

 2 feet long, and often they are pulled from sagebushes or cottonwood 

 trees. Sometimes they are picked up from the ground. Inside the 

 base is a heavy cup of mud held together with some vegetable material. 

 Fresh cow dung sometimes is substituted for the mud. Within the cup 

 is a lining, installed after the construction of the dome and after the 

 nest appears completed. It is composed of rootlets, fine plant stems, 

 or horsehair. 



The dome or canopy built over the whole structure gives the magpie 

 nest its bulky appearance and provides questions of special interest in 

 the life of this bird. This canopy is usually made of thorny twigs, 

 pulled from nearby plants, and it has one or more openings in its side 

 for the birds to enter and leave. Sometimes there is no dome, but this 

 is rare. A nest found by Potter (1927) was in a railroad bridge, 

 directly under one of the rails and between two ties. There was no 

 room for a dome and none was needed. The track was used by at 

 least one train each day. 



Apparently this dome serves as a protection against the raids of 

 predators, especially birds. Throughout the range of magpies their old 

 nests are used also by raptorial birds, often night-hunting owls. Pro- 

 tection from owls may be a chief function of the dome on a magpie nest. 

 An example of this use was observed in Nevada (Linsdale, 1937). On 

 June 6, 1933, at dusk when the long-eared owls became active, magpies 

 near camp showed much concern. Alarm notes were heard at three 

 different magpie nest locations, and birds were seen in flight. Whenever 



