122 BULLETIN 17 0, UNITED STATES NATIONAL MUSEUM 



quiet for some minutes, when the fickle lady-love ceased her clamor and flew to 

 the opposite end of his cross arm. At once he took up cry, alighted beside her 

 and offered the lizard again." This time she readily accepted the offering and the 

 suit was won. 



Nesting. — The nesting habits of the desert sparrow hawk do not 

 differ materially from those of the species elsewhere, except where 

 the birds are forced to make use of such cavities as they can find. 

 It evidently prefers to nest in natural cavities in trees where these 

 are available. In southern California we found it nesting in such 

 cavities in sycamores, willows, and cottonwoods. But in a treeless 

 region, near the coast, I saw two or three pairs that were apparently 

 nesting in some burrows near the top of a high cliff. Here the birds 

 were very solicitous and had their favorite lookout posts on little 

 eminences, or peaks, on or near the top of the cliff, which were well 

 decorated with droppings. I had no means of reaching the holes or 

 of digging them out. 



In Arizona we found them nesting in natural cavities in trees in 

 the wooded canyons; but out on the deserts, where no real trees of 

 any size are to be found, the only available nesting sites were in the 

 giant cactuses, saguaros. These great candelabra, which tower above 

 the low growth of mesquite and greasewood on the deserts, offer 

 ideal nesting sites for many birds of several species. The abandoned 

 nesting holes of Gila woodpeckers and Mearns's gilded flickers are 

 occupied by sparrow hawks, elf owls, saguaro screech owls, Arizona 

 crested flycatchers, ash-throated flycatchers, western purple martins, 

 and cactus wrens. 



Eggs. — The eggs of the desert sparrow hawk are indistinguishable 

 from those of the eastern sparrow hawk. The measurements of 42 

 eggs average 35.1 by 27.5 millimeters; the eggs showing the four 

 extremes measure 37.8 by 27.4, 34 by 30.1, 32 by 27.5, and 33 by 

 22.8 millimeters. 



Young. — Mrs. Irene G. Wheelock (1904) gives the following 

 interesting account: 



For the first week the nestlings are fed exclusively on insects; after that, insects 

 predominate in the nursery menu, although mice are brought several times a day. 

 After leaving the nest they are fed in the tree, for a week or so, before they try 

 to hunt for themselves. The first lesson is very interesting to watch. One of 

 the adults brings a bit of food to the youngster, who is sitting on the perch where 

 for several days he has been fed, and instead of giving it to him, lets it fall in 

 full view, at the same time calling "killy-killy-killy." In nearly every case the 

 young hawk springs after it without hesitation the first time this is tried, and he 

 often gets it. The mother is beside, over, and under him as he drops for it, 

 encouraging him with her calls, and he soon responds with a little cry of unmis- 

 takable triumph. But he is not allowed to eat it on the ground, as he would 

 like to do. An imperative call from the adult makes the young hunter exert his 

 strength and follow to the nearest low perch before he tastes it. 





