Birds from Coahuila, Mexico

by Emil K. Urban

Although Bell's Vireo seems to have been observed uncommonly in Coahuila, this species does breed in the State. Burleigh and Lowery (1942:202) obtained a single female V. b. medius on April 20 "in an arroyo east of Saltillo" and found this subspecies "not uncommon in the open desert twenty miles west of Saltillo, where three singing males were secured." Miller, Friedmann, Griscom, and Moore (1957:226) recorded V. b. medius in breeding condition at Hipólito from June 30 to July 3. Ridgway (1904:207) recorded the subspecies from Monclova. Hardy saw a Bell's Vireo at Parras on July 4, 1955. The size of No. 31495 is typical for V. b. medius.

*Vireo flavifrons Vieillot.—Specimen examined: one, ♂ 32103, from 2 mi. W Jiménez, 850 ft., June 20, 1952.

Van Hoose (1955:302-303) suggested that the occurrence of No. 32103 in Coahuila is evidence of a southward extension of the range of the Yellow-throated Vireo within the last generation. The size of the testes (5×3 mm.) of No. 32103 and the date (June 20) on which it was obtained suggest breeding by Vireo flavifrons in Coahuila.

Vireo solitarius solitarius (Wilson).—Specimen examined: one, ♀ 31640, from 9 mi. E Hermanas (=Canyon de Parajos in the Sierra de Parajos Azule), 2100 ft., December 7, 1953.

This subspecies of the Solitary Vireo is an uncommon migrant or winter visitant to Coahuila. Dickerman obtained No. 31540, whose skull was unossified and whose ovary was small, in an oak and palm habitat. The bright yellow flanks, large and yellow wing bars, and the uniform olive green back indicate that this specimen is a typical representative of V. s. solitarius. This subspecies was previously unrecorded in Coahuila.

Vireo solitarius cassinii Xantus.—Specimens examined: total 2: ♀ 35408 (skeleton only) from 5 mi. W, 3 mi. S Acebuches, 6200 ft., May 12, 1954; and ♂ 31589 from 20 mi. S Ocampo, 6200 ft., April 4, 1954, measurements: wing, 75 mm.; tail, 57 mm.; culmen, 10.5 mm.; weight, 14 gms.

This subspecies of the Solitary Vireo seems to be uncommon in Coahuila. No. 31589 provides the first record of V. s. cassinii in Coahuila. Van Hoose has (1955:303) erroneously reported that Dickerman obtained No. 31589 on July 4, 1954; the correct date is April 4, 1954.

Although the size of No. 31589 is large for V. s. cassinii, the color (sides and flanks with less yellow, more olive; narrow white wing bars) resembles that of typical representatives of cassinii. The testes of No. 31589 were not enlarged. Dickerman suggested that the female from 5 mi. W and 3 mi. S Acebuches showed some resemblance to V. s. plumbeus. This is not to be unexpected since the subspecies plumbeus has been reported from the Chisos Mountains of Texas (Van Tyne and Sutton, 1937:82) and from northern Chihuahua (Miller, Friedmann, Griscom, and Moore, 1957:227).

*Vireo olivaceus (Linnaeus).—Specimen examined: one, ♂ 32104, from 12 mi. N, 12 mi. W Jiménez, 850 ft., June 19, 1952.

The Red-eyed Vireo has been uncommonly reported from eastern Coahuila. Miller, Friedmann, Griscom, and Moore (1957:229) recorded V. olivaceus from Sabinas on May 22 and from Las Vacas Creek on June 7 as late spring migrants. Hellmayr (1935:131) listed the Red-eyed Vireo from northern Coahuila. Findley saw a Red-eyed Vireo 2 mi. W Jiménez on June 19, 1952. The size of the testes (5×3 mm.) of No. 32104 and the date (June 19) on which it was obtained indicate that the Red-eyed Vireo possibly breeds in northeastern Coahuila; if so, this is the first breeding record of the Red-eyed Vireo in Coahuila.