Tanagra affinis affinis Lesson: Lesson Euphonia.—Specimens (2): ♀, 40866, 8.8 gm. (July 22), Pisté; ♂, 40865, testis 3 × 2 mm., 10.0 gm. (August 3), 4 km. WSW (Aeropuerto) Puerto Juarez.
Tanagra lauta lauta Bangs and Penard: Thick-billed Euphonia.—According to Paynter (1955a:272), the only breeding record previously available is that of a male having slightly enlarged testes on February 12. Males taken on July 15 and on August 14 had fully enlarged testes; the gonads of several other specimens were apparently regressing, two specimens had begun to molt, and juveniles were molting into first winter plumage.
Specimens (9): ♂, 40874, testis 7 × 4 mm. (July 15), and ♀, 40875, ova to 1 mm. (July 15), 7½ km. W Escárcega; ♂, 40869, testis 6 × 4 mm., 14.5 gm. (August 14), ♂, 40870, testis 2 mm., 14.5 gm., molting—5th primaries ensheathed (August 14), ♂, 40867, imm., 12.6 gm. (August 14), ♀, 40868, imm., 14.4 gm. (August 14), ♂, 40871, testis 2 mm., 14.4 gm., molting—2nd, 3rd, and 4th primaries ensheathed (August 14), ♀, 40872, ovary granular, 7.8 gm. (August 14), and ♀, 40873, ovary granular, 13.0 gm. (August 15), all taken 4 km. NNE Felipe Carrillo Puerto.
Thraupis abbas (Deppe): Yellow-winged Tanager.—Paynter (1955a:273) reported breeding in this species in late April and late June. Gonads in our specimens were moderately active.
Specimens (2): ♂, 40877, testis 6 × 4 mm., 43.0 gm., molting—1st and 2nd primaries ensheathed (July 15), 1 km. N, 13 km. W Escárcega; ♀ 40876, ovary 7 × 4 mm., (ova to 1 mm.), 42.1 gm. (July 29), Pueblo Nuevo X-can.
Spindalis zena benedicti Ridgway: Stripe-headed Tanager.—Two males in advanced molt but with enlarged gonads were taken on August 9 and 10 and seem to be the first records indicating breeding in this species on Isla Cozumel.
Specimens (3): ♂, 40878, testis 9 × 7 mm., 32 gm., molting—5th primaries and middle pair of rectrices ensheathed (August 9), ♂, 40880, testis 5 × 3 mm., 30.0 gm., molting—3rd, 4th, 5th primaries and middle two pairs of restrices ensheathed (August 10), and ♀, 40879, ovary inactive, 28.1 gm., molting—remiges are new; secondary coverts ensheathed (August 10), 3½ km. N San Miguel, Isla Cozumel.
Piranga roseogularis (Cabot): Rose-throated Tanager.—Breeding has been previously recorded from March 17 through May 11 (Paynter, 1955a:276). Our only specimen, a male in advanced molt, had enlarged (regressing) testes.
Specimen (1): ♂, 40881, testis 7 × 5 mm., 24.2 gm., molting—4th and 5th primaries ensheathed (August 15), 4 km. NNE Felipe Carrillo Puerto.
Habia gutturalis (Sclater): Red-throated Ant-tanager.—The only breeding records previously available for this species on the peninsula are for May 18 (Paynter, 1955a:280) and June 25 (Paynter, 1955b). Specimens taken between July 14 and August 2 were in full breeding condition. A male (40882) and female (40883) taken 7½ km. W Escárcega were known to be mated. Plumages in all specimens are worn and for that reason specimens were not identified to subspecies.