1914] Grinnell: Mammals and Birds of the Colorado Valley 85 



Saguaro Association 

 birds 



Falco sparverius phalaena: max.; Colaptes chrysoides mearnsi: max.; 



resident resident 



Otus asio gilmani: rain.; resident Myiarchus cinerascens cinerascens: 



Micropallas whitneyi: excl.; resident max.; summer 



Centurus uropygialis: max.; resident Carpodacus mexicanus frontalis: 



min.; resident 



MAMMALS 

 (As far as known, same as in creosote association.) 



Remarks upon the Saguaro Association. — The conspicuous columns 

 of the giant cactus or saguaro (Cereus giganteus) first met our expect- 

 ant gaze just below the mouth of Bill Williams River. There, on both 

 sides of the Colorado, for a stretch of two miles or more, stood many 

 specimens growing on the hill slopes in full view from the river as 

 we floated by. A landing was made on the California shore, and sev- 

 eral saguaros closely examined for nesting sites of birds. We next 

 found these cactuses on the open desert one to three miles east of 

 the river on Arizona territory around Ehrenberg. There were so many 

 here that they formed a distinct tract, extending across the mesas and 

 occupying the interlying washes as well. 



Giant cactuses again came to view some ten miles below Picacho, 

 two or three individuals being seen on the California side and many 

 on the Arizona side. Finally, on the mesa on both sides of the river, 

 three to five miles above the Laguna dam, saguaros were plentiful. 

 On the California side from one hundred yards to two miles back from 

 the outer edge of the river bottom were about seventy-five individuals 

 (see pi. 9. figs. 12, 13). Thirty-seven, big and little, were counted by 

 the writer as in sight from one point. 



It was gratifying thus to find this unique plant well represented 

 on California ground. For coming with it into the state of California 

 were the several birds listed, an assemblage altogether justifying the 

 designation of a saguaro association. This association is best devel- 

 oped in a large area of southwestern Arizona. The tongue crossing the 

 Colorado River above Laguna and Potholes is undoubtedly an exten- 

 sion of it. 



As far as we were able to learn, in other plant elements and in 

 mammals, the saguaro association was here identical with the creosote 



