This subspecies of the Brown-headed Cowbird is common in Coahuila and breeds there. Amadon and Phillips (1947:579) suggested that M. a. obscurus breeds at Las Delicias. Burleigh and Lowery (1942:206) saw the Brown-headed Cowbird in "small numbers on the outskirts of Saltillo...."
Measurements of the adult males that I have examined are: wing, 101.1 mm. (97-106); tail, 66.5 mm. (62-69); tarsus, 25.6 mm. (24.5-28); culmen, 17.3 mm. (16-18.5). Measurements of the adult females that I have examined are: wing, 92.3 mm. (90-97); tail, 60.1 mm. (56.5-62.5); tarsus, 23.5 mm. (22.5-24); culmen, 14.4 mm. (14-15). The sizes of the testes of three of the males (6-7 mm. long) and of the largest ova of four of the females (6-9 mm. in diameter) indicate breeding by this subspecies in Coahuila, as does the small size of one of the juvenile males (tail, 33.5 mm. long).
Piranga ludoviciana (Wilson).—In Coahuila the Western Tanager occurs fairly commonly as a migrant. There are no records of it breeding in the State. Miller (1955a:174) remarked that Marsh took a migrant Western Tanager at Jardín del Sur in the Sierra del Carmen on September 7. Amadon and Phillips (1947:579) took an adult male Western Tanager at Las Delicias on August 12. Miller, Friedmann, Griscom, and Moore (1957:305) also recorded this tanager from 12 mi. W Saltillo. Dickerman saw Western Tanagers in the Sierra del Pino on May 12, 1954, and 16 mi. E and 18 mi. N Ocampo on May 7, 1954.
*Piranga flava dextra Bangs.—Specimen examined: one, ♂ 31526, from Sierra del Pino (=5 mi. S, 3 mi. W Acebuches), May 12, 1954, weight, 41 gms.
Miller (1955a:174) found this subspecies of the Hepatic Tanager "in the pine-oak belt at 7000 feet on April 12 [in the Sierra del Carmen], when a male was seen and a female taken." No. 31526 was with a female when taken; this male was not fat and its testes were not enlarged. The size of the wing (105.5 mm.) of No. 31526 represents the extreme maximum in this subspecies.
Piranga flava hepatica (Swainson).—Miller, Friedmann, Griscom, and Moore (1957:303) stated that P. f. hepatica is found in northwestern and central Arizona and southwestern New Mexico south into the highlands of México, west of the Sierra Madre Oriental, to Oaxaca and in winter and migration extends eastward and south to Chiapas. These authors remarked also that P. f. dextra occurs in the mountains east of the continental divide in New Mexico and western Texas south through eastern México to Chiapas. Specimens of the Hepatic Tanager from Coahuila in winter might well be either P. f. hepatic or P. f. dextra. Miller, Friedmann, Griscom, and Moore (loc. cit.) recorded migrants of P. f. hepatica from the Sierra de Guadalupe on April 24-27.
*Piranga rubra rubra (Linnaeus).—Specimens examined: total 6: ♂ 32129, ♂ 32132, and ♀ 32133 from 12 mi. N, 12 mi. W Jiménez, 850 ft., June 18 and 19, 1952; ♂ 32130 from 2 mi. W Jiménez, 850 ft., June 20, 1952; and ♂ 32131 and ♀ 32134 from 2 mi. S, 11 mi. E Nava, June 15, 1952.
This Summer Tanager occurs in northeastern Coahuila. The specimens from 12 mi. N and 12 mi. W Jiménez, 2 mi. W Jiménez, and 2 mi. S and 11 mi. E Nava are typical representatives of P. r. rubra. The large testes (12 mm.) of No. 32129 and the well-developed brood patch of No. 32134 are evidence of breeding by this subspecies in the State. Heretofore this subspecies has not been recorded from Coahuila.
*Piranga rubra cooperi Ridgway.—Specimens examined: total 4: ♂ ♂ 32828-32829, ♂ 32831, and ♀ 32830 from Parras, July 4, 1955.
This subspecies of Summer Tanager seems to occur throughout Coahuila except in the northeastern section of the State. Miller, Friedmann, Griscom, and Moore (1957:302) listed P. r. cooperi from Sabinas and Sierra de Guadalupe. Miller (1955a:174) saw a Summer Tanager in a canyon in the Serranías de Burros, about 40 miles east of the Sierra del Carmen on April 28. Although there are no other records of P. r. cooperi from northwestern Coahuila, Van Tyne and Sutton (1937:96) recorded this tanager as a common nesting species in Brewster County, Texas, in cottonwood, mesquite, or willow trees. I suspect that P. r. cooperi is a common nesting bird in northwestern Coahuila as well.