Emil K. Urban

“ For instance, at Yakutat Bay in southeastern Alaska the South American element of breeding passerine species was 3 per cent, the North American element 39 per cent, and the Old World element 58 per cent whereas at Sonora, México, the South American element of breeding passerine species was 27 per cent, the North American element 52 per cent, and the Old World element 21 per cent. The breeding avifauna of Coahuila is thus in line with Mayr's analysis, resembling that of Sonora to a considerable degree at the taxonomic level of Family. ”

“ No specimens of the Caracara have been taken from Coahuila.
Falco mexicanus Schlegel.—Specimen examined: one, ♂ 31596, from Saltillo, January 10, 1954.
The Prairie Falcon is an uncommon winter visitant in Coahuila. Friedmann, Griscom, and Moore (1950:65) indicated that Falco mexicanus winters south to Sonora, Oaxaca, Chihuahua, Durango, Zacatecas, Auguascalientes, Hidalgo, Nuevo León, and Tamaulipas.
No. 31596 is the first recorded specimen of the Prairie Falcon from Coahuila. The bird was heavily parasitized by worms in the mesenteries and seems to be an adult. ”

“ The two subspecies of the Violet-green Swallow, thalassina and lepida, intergrade in Coahuila. Specimens from different localities in the State represent various stages of intergradation between the two subspecies; generally those from northern Coahuila seem to be closer to T. t. lepida, and those from southern Coahuila are closer to T. t. thalassina. Nos. 31471-31473 are intergrades between T. t. thalassina and T. t. lepida; in size the three resemble T. t. thalassina, but in green, rather than purple, backs and scapulars resemble T. t. lepida. ”

“ It is instructive to consider also the origin of avifaunal elements at the level of Family. According to Mayr (1946:11) most North American families and subfamilies clearly originated in the Old World, in South America, or from a North American element that developed in the partial isolation of North America in the Tertiary. Three other elements, the Panboreal, the Pan-American, and the Pantropical are represented by some North American families and subfamilies. Because of the obscurity of the place of origin of certain groups, an additional unanalyzed element must be recognized. ”

“ Nos. 31645 and 32041 differ from semplei in that the tops of their heads do not appear to be solid blackish brown at a distance of four to five feet and in that the dark streakings of their backs and scapulars are not so heavy as in semplei. The mentioned specimens are brownish, not more black and white throughout as in suttoni nor are their toes heavily feathered (see Moore, 1941:154) . ”

“ Meco, Sierra Guadalupe (=10 mi. S General Cepeda) , 6500 ft., April 23, 1953, weights, 17, 18 gms.
Typical populations of this White-breasted Nuthatch occur in southern Coahuila. Ridgway (1904:449) listed S. c. mexicana from Sierra Guadalupe in southern Coahuila. The underparts of our specimens are darker than in nelsoni, and their bills (culmen, 15, 13 mm.) are shorter than the average (♂, 19.8 mm.; ♀, 18.6 mm. [Ridgway, 1904:447] ) in nelsoni. The large size of the testes (5×3 mm.) of No. 31669 suggests breeding by S. c. mexicana in Sierra Guadalupe. ”

“ There remain several kinds of birds that are not especially associated with any one or two of the above-named provinces. These birds are widely distributed and vary geographically without corresponding to the Biotic Provinces. ”

“ E Bella Unión, 7200 ft., June 25, 1952.
Miller (1931:66) suggested that L. l. mexicanus and L. l. excubitorides intergrade in Coahuila; all of the specimens of Loggerhead Shrike from Coahuila that I have examined are intergrades between mexicanus and excubitorides. Our four specimens have a superciliary line that is indistinct and the black mask of each extends somewhat posterior to the auricular region. The anterior part of their forehead is somewhat lighter than the remaining part of their head and back. ”

“ The following birds are associated with this province: Black Vulture, Scaled Quail (C. s. pallida) , Turkey, Elf Owl, Green Kingfisher, Hairy Woodpecker (D. v. icastus) , Ladder-backed Woodpecker (D. s. cactophilus) , Wied's Crested Flycatcher, Buff-breasted Flycatcher, Vermilion Flycatcher (P. r. flammeus) , Black-crested Titmouse (P. a. dysleptus) , Cactus Wren (C. b. couesi) , Curve-billed Thrasher (T. c. celsum) , Blue-gray Gnatcatcher (P. c. amoenissima) , Hutton's Vireo (V. h. carolinae) , Summer Tanager (P. r. cooperi) , and Black-throated Sparrow (A. b. opuntia) . ”