202 Bergtold, The Crow in Colorado. [April 



are too near the dividing line to be definitely located as to sub- 

 species, all showing characters of one or of the other of the two 

 forms under study, in varying degrees of intensity. 



1 have been able to study but one Crow skin from the western 

 slope in Colorado, to-wit, a skin in my collection, which was taken 

 at lgnacio, Colorado, in October, 1917, by my friend and colleague, 

 Dr. Walter L. Mattick; fortunately it is the skin of a male, and is 

 typical hespcris. 



We are now on firm ground; those skins from the eastern slope 

 which are most likely to be characteristic of a given subspecies, 

 to-wit, males, show that both brachyrhynchos and hesperis are to be 

 found on that slope, and the lgnacio skin proves that hesperis 

 occurs on the western slope. 



Hence one can say now that both Corvus brachyrhynchos brachy- 

 rhynchos and Corvus brachyrhynchos hesperis are to be included in 

 future lists of Colorado birds. 



The common Crow is normally a bird of moderately large and 

 fairly dense timber, a growth found in Colorado only along the 

 larger streams and in the mountains ; if one plot the Crow stations 

 of Colorado on a map, it at once becomes patent that most, if not 

 ali, of these stations are to be found along the courses and head- 

 waters of the State's larger streams. This fact seems to lend color 

 and support to the idea that subspecies brachyrhynchos probably 

 penetrated Colorado from the east by following the larger streams 

 towards the mountains, for it is along these rivers that one finds 

 trees to the Crow's liking, and too, Crows are increasingly more 

 common as one travels eastward along these watercourses. It 

 would seem reasonable to believe that along similar natural "crow" 

 highways hesperis would find its way eastward from the Pacific 

 side into Colorado. 



The smaller size, alone, of hespcris, often makes it distinguishable 

 in the field, a fact which first came to my attention while in the 

 "hills" on the Gila River in New Mexico, in 1906. During the 

 same year 1 saw a considerable flock of Crows immediately south 

 of Antonito, Colorado ; 1 was then again impressed by the smaller 

 size of these southern Colorado and New Mexico Crows. 1 now 

 believe these Antonito Crows were subspecies hesperis; Antonito 

 is on (or very close) to the Rio Grande River, which drains part 



