NATURAL SCIENCES OF PHILADELPHIA. 39 



List of the BIRDS of Fort Whipple, Arizona : with which are incorporated 



all other species ascertained to inhahit the Territory ; with brief 



critical and field Notes, descriptions of new species, etc. 



BY ELLIOTT COUES, A. M., M. D. 

 (Assistant Surgeon U. S. Army.) 



The Territory of Arizona comprises that portion of what was formerly the 

 vast Territory of New Mexico lying west of the 109th meridian; together with 

 an extensive tract obtained from Mexico, known as the " Gadsden purchase." 

 As at present bounded, Utah and Nevada form its northern limit, while its 

 southern border is contiguous in its whole extent to the Mexican State of 

 Sonora. The Colorado River separates the greater portion of its western 

 border from California ; the extreme southwestern corner of the Territory 

 being at the junction of the Gila with the Colorado River. 



The extensive area thus bounded, constitutes, in connection with New Mex- 

 ico, what is known, in relation to its Faunal characteristics, as the " South- 

 ern Middle Province" of the United States.* It possesses marked features 

 whereby it is distinguished from the western littoral Province, or Pacific 

 region proper, as well as from the Eastern Province. Most of the character- 

 istics of the Arizonian Avifauna are shared to a considerable degree by that 

 of New Mexico; the main points of discrepancy being those few wherein the 

 valley of the upper Rio Grande differs from that of the Colorado. It does 

 not appear that the difference between the two slopes of the main chain of 

 the Rocky Mountains is in this region very strongly marked. In general 

 terms it may be affirmed that the Ornis inclines in character decidedly to- 

 wards that of the Pacific region proper, as might be expected from the posi- 

 tion of Arizona relative to the main chain of the mountains just named. But 

 still notable differences from the truly littoral Fauna are apparent ; and there 

 can be little doubt that the presence of so extensive a desert just west of the 

 Colorado exerts much influence in producing this result. At certain points 

 however in this desert, some species, respectively typical each of its own 

 habitat, are known to meet.f The features, dependent upon latitude, which 

 separate Arizona from adjacent regions, to the north or south, are by no 

 means so marked as those which distinguish it from the countries lying east 

 and west, and mainly consist in the introduction into the lower warmer parts 

 of the Territory, from Sonora, of several Mexican and subtropical species. A 

 "wedge," so to speak, of these types is pushed a little northward of Mexico, 

 and they are readily recognizable as a somewhat prominent element among 

 the birds of Southern Arizona, and of the Colorado valley for a considerable 

 distance. Perhaps this is more deciedly the case here than at other points 

 on our southern border. A considerable number of species properly belong- 

 ing to the United States Fauna, and generally distributed throughout Ari- 

 zona, retire in winter beyond the Sonoran border ; while at the same time it is 

 interesting to note that some speciesj breed quite high up in Arizona, or even 

 further north, which are at the same time summer residents of the table lands 

 of Mexico. To the northward, neither the climate nor physical geography of 



* See the American Journal of Science and Arts, vol. xli., Jan. and March, 18fi6 ; " On the Dis- 

 tribution and Migration of North American Birds, by Spencer V. Baird," where the several pro- 

 vinces into which North America is divisible are characterized, and the peculiarities of their Avi- 

 faunae indicated. 



\ E. g. The Lnphortyx Gambeli and L. Californicus, and very probably also some species of 

 Jays; along theMojave River, which rises in the San Beinadino Mountains, and flows eastwanlly 

 towards the Colorado River, affording a degree of fertility which is an inducement to the species 

 just named and to others. 



% E. g. Hesperiphona vespeitina, Carpodacus Cassinii, Curvirostra americana, Plectrophants 

 melanomus,etc. 



1866.] 



