124 University of California Publications in Zoology L VoL - 12 



Accipiter velox (Wilson) 

 Sharp-shinned Hawk 



Apparently a common winter visitant to the Colorado River bot- 

 tom, adhering closely to the willow belt. Seen in the vicinity of 

 Needles, February 16, 20, and 21; at Mellen, February 24; in Cheme- 

 huevis Valley March 9 ; ten miles south of Cibola April 8 ; twenty miles 

 above Picacho, April 14 and 16; and five miles above Laguna April 

 24. The latter date probably indicates about the time of departure. 

 Two specimens were obtained, nos. 12690, 12691. 



There is also in the Museum a skin (no. 4380) taken by J. G. 

 Cooper at Fort Mohave, January 4, 1S61. 



Accipiter cooperi (Bonaparte) 

 Cooper Hawk 



Seen in February and March ; to our surprise this proved to be also 

 a breeding species of the region. It was confined almost altogether 

 to the timbered bottom lands. Definite points and dates of observation 

 were: Mellen, February 26; above Bill Williams River. March 13; 

 eight miles east of Picacho, April 19 ; four miles north of Potholes, 

 April 23; five miles north of Laguna. April 24; Potholes, April 29; 

 and five miles northeast of Yuma, May 3. 



On April 19 a female bird (no. 12693), with two eggs, was secured 

 on the California side eight miles east of Picacho. The nesting site 

 was in a tract of tall willows, free from undergrowth, and closely 

 paralleled by the river on one hand and an open mud flat on the other. 

 The nest tree was relatively slender and leaning, its top about on a 

 level with the crowns of the rest of the grove in the vicinity, and 

 stood fifty yards from the river's edge. The nest was about twenty- 

 five feet above the ground, lodged among the branches of the willow 

 near its top, and was a small, loosely constructed platform composed 

 wholly of dry willow twigs. The two eggs it contained were fresh. 

 Although the female bird had already begun to sit closely, as we were 

 able to determine because the nesting site happened to be only a few 

 yards from our camp at this place, the set was incomplete. Dissection 

 of the bird showed that two more eggs would have been laid. 



One of the eggs of the set (Mus. no. 765) has sparse speckling 

 of liver brown about the large end; both have equivocal nest stains; 

 otherwise they are very pale nile blue. They are small, measuring 





