Hknnixger-Jones — On Fai.coxes of Xorth America. 83 



composed of a few bits of twigs, rotten wood, with a little 

 moss, wool, or feathers. 



Eggs. 



From three to five, laid from March to July, depending on 

 the latitude. The eggs are rounded ovate, creamy white or 

 buffy, spotted with cinnamon browai, reddish brown, or choc- 

 olate. Size about 53 x •^12.2 mm. The eggs vary greatly 

 in color and size. Incubation lasts about 28 days, both par- 

 ents sharing. 



FALCO MEXICANUS (Schleg). 

 Prairie Falcon. 



Geographical Distribution. 

 United States, from the eastern border of the plains, and 

 from the Dakotas south into Mexico ; casual eastward to 

 Illinois. Breeds throughout the United States range. 



Measurements. 



Male: Length 43, wing 30. 8G, tail 17.15, culmen 1.07, 

 tarsus 4.45, middle toe 4.86. 



Female : Length 48.26, wing 35.24, tail 20.19, culmen 2.35, 

 tarsus 5.53, middle toe 5.46. 



Diagnostic Marks. 

 A blackish patch on the side of the throat, distinctly streak- 

 ed under parts, and a gray-brown back. Strong, quick, 

 dashing flight. 



Color Pattern. 



Adult : Top of head sooty black, or deep black, distinctly 

 darker than the back : under parts varying from pure white 

 to creamy buft, distinctly but not heavily marked with black- 

 ish, rarely unmarked below. 



Yonng: Lower parts more buffy and striped with dusky, 

 upper parts with the colors obscured by brownish edgings 

 of the feathers. 



