THE APLOMADO FALCON, 307 



tioned at Fort Huacliuca, in southern Arizona, and which he generously 

 presented to the U. S. National Museum collection at Washington, D. C, are 

 three sets of eggs of this Falcon. He writes me that he found it exceed- 

 ingly shy and difficult to approach, but fairly common in that vicinity. 

 According to his observations it often alights on the ground when pursued, 

 and prefers the open plains, covered here and there with low mesquite ti-ees, 

 .yuccas, and cactuses, to the more mountainous regions. He does not consider 

 it a resident throughout the year, but he observed it as late as January. 

 Five nests were found by the lieutenant during the spring of 1887, all of 

 them placed in low mesquite trees from 7 to 15 feet from the ground. 

 These nests were apparently old ones of the White-necked Raven (Corviis 

 cryptoleucus), and used without any repairs being made to them. A nest 

 found on April 25, 1887, contained three young birds, which were taken by 

 him and raised, becoming quite tame; one found on April 28 contained 

 three fresh eggs ; another found on May 5 likewise contained three eggs, 

 two with large embryos, the third addled. A fourth and fifth nest, both 

 found on May 14, contained each two fresh eggs, possibly a second laying 

 of some of the birds previously despoiled. 



Their food consists of small reptiles, mice and other rodents, grasshop- 

 pers and insects of various kinds, and occasionally a bird. 



The usual number of eggs laid by this species seems to be three ; but 

 nothing is known about the length of incubation. Nidification commences, 

 occasionally at least, by the latter part of March, continuing through April 

 and the first half of May, and it is not likely that more than one brood is 

 raised in a season. It seems to be only a summer resident in the United 

 States. 



The ground color of the eggs of the Aplomado Falcon is a dirty yel- 

 lowish white, and this is thickly sprinkled with reddish and chestnut brown 

 blotches and spots of various sizes, almost completely obscuring the ground 

 color. In one of the sets of eggs these markings are very fine, nearly of 

 the same size throughout, and of a delicate reddish buff color, giving them 

 quite a different appearance from the others. Judging from the limited 

 number of specimens in the collection, their variation in color is fully as 

 great, if not greater, than that found in the eggs of any of our Falcons. 

 In general appearance they approach the eggs of Falco rusticolus gyrfalco 

 nearer than any others. 



The average measurement of nine specimens in the U. S. National 

 Museum collection is 45 by 35 millimetres. The largest specimen measures 

 46.5 by 35, the smallest 43 by 35 millimetres. 



Of the type specimens. No. 23001 (PI. 10, Fig. 9), from a set of three 

 eggs, was taken May 5, 1887, and No. 23020 (PI. 10, Fig. 10), also from a 

 set of three taken on April 28, 1887. Both were collected by Lieut. Harry 

 C. Benson, U. S. Army, near Fort Huachuca, Arizona. 



