126 University of California Publications in Zoology [Vol.12 



Falco columbarius richardsoni Ridgway 



Richardson Pigeon Hawk 



There is in the Museum a female specimen (no. 4388) taken by 

 J. G. Cooper at Fort Mohave. January 21, 1861. 



Falco sparverius phalaena (Lesson) 

 Desert Sparrow Hawk 



First noted March 31, two flying north over the river ten miles 

 below Ehrenberg. Next observed April 15, twenty miles above Picacho. 

 Otherwise found only in the saguaro belt on both sides of the river 

 within five miles above the Laguna Dam. Here the species found 

 favorable nesting sites in the deserted burrows in the giant cactuses, 

 made by gilded flickers and Gila woodpeckers. A set of five eggs, in 

 which incubation was far advanced, was found eleven feet above the 

 ground in an eighteen-foot saguaro on the California side, April 23. 

 An elf owl was taken at the same time from a hole in the opposite 

 side of the trunk. The excavation in which the hawk's eggs were laid, 

 opened to the south. 



The only specimen secured by the expedition was an adult female 

 (no. 126S9) shot among the saguaros on the Arizona side of the 

 river five miles above Laguna. April 22. This bird is markedly 

 different from any one of a series of twenty-seven adult females from 

 California. Nevada, Washington, Alaska, and the western United 

 States generally, which series I would call Falco sparverius spam rius. 

 Yet it does not accord, particularly in size, with Mearns's characteriza- 

 tion (1892, p. 263) of Falco sparverius deserticola. As compared with 

 average examples of sparverius, as represented in the series referred 

 to, the specimen in question is decidedly smaller, except bill : wing 178, 

 tail 113, tarsus 34, middle toe and claw 31, bill from nostril 11, culmen 

 from cere 12, depth of bill 9.4; the browns of the upper and under 

 surfaces are more reddish, the brown area on top of head very broad 

 and pure cinnamon-rufous without trace of plumbeous shaft-streaks, 

 the plumbeous of head reduced to narrow frontal and superciliary 

 tracts continuous with one another, shaft-streaks of pectoral region 

 narrow, barrings on dorsum very narrow, the widest only 3 mm. 

 instead of 7. 



