PRAIRIE FALCON 19 



Spring. — Throughout the more northern and colder parts of its 

 range the prairie falcon is migratory, generally retiring toward the 

 south to escape the coldest weather, especially in the Rocky Moun- 

 tains and east. In the Yellowstone National Park I found them 

 passing through on migration, appearing after March 25. Farther 

 east, in northeastern Wyoming, they are rare, arriving usually about 

 April 10 or 12, according to Peabody (1907). In Colorado, they are 

 common in the warm months but all leave the mountains during 

 winter. Still farther east they are seen occasionally in Kansas, 

 Missouri, and the Dakotas; but south of these States prairie falcons 

 are resident, except perhaps on the highest mountains. 



Courtship. —Dawson (1923) gives an interesting account of the 

 courtship of this falcon: 



About the brink of the precipice a dozen Falcons are at play. It is courting 

 time and the birds are showing off. The females are the larger birds, but it is 

 their turn to sit in the boxes while the aspirants perform. The doughty males 

 are not really contending — only renewing their vows as they come hurtling out 

 of the heavens, screaming like all possessed and cutting parabolas whose acute- 

 ness is a marvel of the unexpected. The female screaks in wild approval, or takes 

 a turn herself because she cannot contain her fierce emotions. The rock walls 

 resound with boisterous music, and the observer feels as though he were wit- 

 nessing the play of elemental forces — riotous, exultant, unrestrained, the very 

 passion of freedom and conquest. 



Nesting. — Although the discovery of a prairie falcon nest is an event 

 to be cherished, it is still more rare to see a pair hunting for a site. 

 Harry S. Swarth (1904) tells us: "On April G, 1902, Mr. Howard 

 and I watched a pair flying about a rocky cliff in Ramsey Canyon. 

 They were apparently in search of a nesting site for they flew into 

 quite a number of caves and crevices in the rock, screaming shrilly 

 the while, but on a later visit to the place we failed to find them." 



In the open, rough sagebush country of California, Oregon, and 

 Washington, prairie falcons choose for their nesting sites outcroppings 

 of rocks, or cliffs, 50 to 400 feet in height and usually perpendicular. 

 The sites chosen are generally 30 feet or more above ground and inac- 

 cessible to man, except by ropes from above. In the northeastern 

 part of their range falcons are known to nest in the badlands of 

 Montana, Wyoming, and western North and South Dakota, although 

 rarely in eastern North and South Dakota. There are only a few 

 records of occurrence in Minnesota and none of nesting sites (Roberts, 

 1932). A preferred site faces out over open country, and a southern 

 exposure is often chosen, for the bright hot sun seems to cause no 

 discomfort. Where there are neither cliffs nor crevices these birds 

 will nest in all sorts of niches in any kind of wall, even in dirt banks. 

 Consequently, while the average site is very characteristic, nests 

 may be found almost anywhere. Decker and Bowles (1930) say that 

 "in one nest we took a handsome set of five eggs after no more of an 



