THE CROW IN COLORADO.
BY W. H. BERGTOLD.
A study of the technical status, and distribution of the Crow in Colorado discloses, at once, an interesting, and a peculiar situation.[17]
The Crow was first recorded in Colorado, so far as I am able to learn, by Aiken (1), who reported it in this State in 1872 under the name Corvus americanus; thereafter several other writers mentioned the bird, as having been found in Colorado:—Ridgway in 1877 (2), Stephens in 1878 (3), and Drew in 1881 and 1885 (4), all using the same name employed by Aiken.
Ridgway (5) erected the subspecies hesperis in 1887, at that time giving its range substantially as outlined today by the A. O. U. ‘Check-List’; the validity of this subspecies was not admitted by the A. O. U. Committee until July, 1908 (6). In his original description of the new subspecies (hesperis) Ridgway did not state how many skins he examined nor whence they came, but gave as the eastern limit of the new subspecies “east to the Rocky Mountains,” while in his later account (7) of hesperis, for which he utilized twenty-three skins for study purposes, he carefully qualifies the eastern limit by adding “from the Eastern portion of the arid region?” It is to be noted that he did not definitely mention Colorado as being included within the hesperis area; in his coincidental review of the literature possibly related to the new subspecies, however, all citations of previous records of Colorado Crows are grouped under the literature of subspecies hesperis. This probably was done because he did not have time to sift out the records relating to the eastern slope from those of the western slope so as to place them under the literature relating to the individual subspecies. So far as Colorado is concerned in this question, Ridgway probably did not take this matter up in detail because there is not a single Crow skin in either the National Museum, or in the Biological Survey Collections, which came from Colorado.
Most, if not all, of the writers who thereafter, directly or indirectly, touched on the Crow’s position in Colorado, made their diagnoses as to subspecies on regional grounds alone.
In the interval between Ridgway’s erection of subspecies hesperis, and its admittance to the A. O. U. ‘Check List’ (1887 to 1908) Morrison (8) and Drew (19) were, so far as I know, the only writers to record the Crow in Colorado, Morrison mentioning it first, as Corvus frugivorus and the second time (9) as Corvus americanus, while Drew entered his record under the latter name.
Cooke’s ‘List of the Birds of Colorado’ was published in March 1897, and in it he grouped all of the previous Colorado Crow records, regardless of region, under the name Corvus americanus; notwithstanding that Ridgway had ten years previously separated the eastern and the western Crows, Cooke (22) logically disregarded this action, because he followed the A. O. U. ‘Check-List’ in assembling his ‘List of Colorado Birds.’ In all the various supplements which Cooke published to his list (the last being in ‘The Auk’ of October 1909) he did not change his early naming of the Colorado Crows, allowing them to stand as Corvus americanus or its synonym. I am confident that he recognized the probability of there being two subspecies in the State, but wisely refrained from opening the question because of lack of material available for definite determination. Furthermore I am given to understand that there are no Crow skins in the collections of the State Agriculture College at Fort Collins, where Cooke was located when he compiled his ‘List,’ which fact would lend support to the idea that his omission to mention the possibility of both the Eastern and the Western Crows being found in Colorado was due to his unwillingness to pass judgment on a question without the support of definite material or data.
In his ‘The Present Status of the Colorado Check-List of Birds’ (10), Cooke again was silent as to the presence of subspecies brachyrhynchos or of hesperis or of both within the confines of Colorado, though at least three writers (11), (12), (13), had previously mentioned the Colorado Crow in their respective papers, as being hesperis; Cooke was too careful and experienced an ornithologist to have overlooked these records and I am sure his silence was judiciously intentional and premeditated.
It thus appears that between 1887 and 1912 the Crows of Colorado had been recorded by some observers, so far as subspecies were concerned, as brachyrhynchos, and by others as hesperis, but so far as I know and am able to learn, none suggested or recorded that these two subspecies coexisted in the State.