NORTH AMERICA AND THE WEST INDIES 69 



mountainous region of the State. The same author (Warren, 

 1926) has given a detailed account of beaver colonies in Estes 

 Park, Colo., with descriptions and photographs of their haunts 

 and works, as well as maps illustrating their engineering enter- 

 prises. Under protection the beaver seems for the present 

 fairly safe in Colorado. 



SOUTHWESTERN BEAVER; BROAD-TAILED BEAVER; 

 SONORAN BEAVER 



CASTOR CANADENSIS FRONDATOR Mearns 



Castor canadensis frondator Mearns, Preliminary Diagnoses of New Mammals of the 

 Genera Sciurus, Castor, Neotoma and Sigmodon, p. 2, 1897; reprinted in Proc. U. S. 

 Nat. Mus., vol. 20, p. 502, Jan. 19, 1898 (San Pedro River, Sonora, Mexico, near 

 monument No. 98 of the Mexican boundary line). 



FIG.: Mearns, 1907, p. 351, fig. 57 (skull). 



Like the southeastern beaver (C. c. carolinensis) , this is a 

 broad-tailed race, but its color is paler and brighter. Vernon 

 Bailey (1931) describes it as light chestnut above; middle of 

 the belly reddish chestnut; hind feet dark chestnut; colors 

 slightly darker in winter. Total length, 1,070 mm.; tail from 

 anus, 360; hind foot, 185; skull length, 133, its width 99. 

 Weight of type (a female), 62 pounds. Old males are slightly 

 larger than females and may measure up to 1,130 mm. in length. 



This race of beaver extends slightly to the south of the 

 Mexico-United States boundary in northern Sonora and is 

 found in Arizona along the Colorado River and in the extreme 

 western part of New Mexico on branches of the Gila and San 

 Juan Rivers. According to Bailey (1931) it is the form found 

 from all points whence specimens were examined along the 

 Colorado River system, but although formerly numerous, it is 

 now everywhere much reduced in numbers. "There are still a 

 few beavers in the headwaters of the Gila . . . also some 

 in the San Juan River and its tributaries" in western New 

 Mexico. Mearns (1907) has also given many details of its 

 presence during the latter part of the last century along the 

 Mexican boundary of Arizona. Within the rather restricted 

 range at present assigned to this race, it is evidently rare and 

 likely to be further reduced in the future. 



