Specimens (6): ♂, 40882, testis 14 × 9 mm., 38.9 gm. (July 14), ♀, 40883, ovary 5 × 5 mm., 29.0 gm. (July 14), and ♂, 40887, testis 10 × 7 mm. (July 16), 7½ km. W Escárcega; ♂, 40885, juv. (rectrices and remiges ensheathed basally) (July 28), and ♀, 40886, ovary moderately active, 30.5 gm., molting—2nd primaries ensheathed (July 28), Pueblo Nuevo X-can; ♂, 40884, testis 15 × 8 mm. (August 2), 4 km. WSW Puerto Juarez.
Saltator atriceps (Lesson): Black-headed Saltator.—Previously, breeding has been noted in this species in February, March, and April (Paynter, 1955a:284). A male taken on July 16 was in full breeding condition.
Specimens (3): ♂, 40895, testis 15 × 9 mm., 80.4 gm. (July 16), and ♀, 40896, 73.5 gm. (July 17), 7½ km. W Escárcega; ♂, 40894, 71.6 gm. (July 29), Pueblo Nuevo X-can.
Saltator coerulescens (Vieillot): Gray Saltator.—The only previous breeding record for this species is for April 26. Our one specimen, No. 40897, a juvenal male barely able to fly, taken on July 21 at Pisté, weighed 43.8 grams.
Richmondena cardinalis (Linnaeus): Cardinal.—The only record of breeding previously reported is of a male with enlarged testes taken on June 4 (Paynter, 1955a:287). Adult males with enlarged testes were obtained on July 11 and August 10, and three juveniles were taken southwest of Sisal on August 10, 16, and 18.
Specimens (7): ♂, 40903, testis 9 × 7 mm., 39.7 gm. (July 11), and ♀, 40904, 34.0 gm. (July 11), 5 km. S Champotón; ♂, 40898, testis 7 × 4 mm., 33.8 gm. (August 10), and ♀, 40899, juv. (rectrices and remiges ensheathed basally), 32.8 gm. (August 10), 13 km. WSW Sisal; ♂, 40900, fledgling, 18.4 gm. (August 18), 2 km. WSW Sisal; ♀, 40901, ovary granular, 37.4 gm., molting—1st primaries ensheathed (August 15), and ♂, 40902, imm., 34.0 gm. (August 16), 4 km. NNE Felipe Carrillo Puerto.
Cyanocompsa parellina (Bonaparte): Blue Bunting.—Specimens (2): ♂, 40906, imm. (July 15), and ♂, 40905, testis 10 × 7 mm., 15.2 mm. (July 15), 7½ km. W Escárcega.
Tiaris olivacea pusilla (Swainson): Yellow-faced Grassquit.—The only records of breeding, thus far, are by Paynter (1955a:291) for March 12 and June 14. A male (40907) taken 4 km. NNE Felipe Carrillo Puerto on August 14 had fully enlarged testes (8 × 5 mm.).
Tiaris olivacea intermedia (Ridgway): Yellow-faced Grassquit.—Although females taken on Isla Cozumel exhibited no reproductive activity, two males had moderately enlarged testes. These seem to be the first records of breeding in this subspecies, which is endemic to Isla Cozumel.
Specimens (5): ♂, 40908, testis 6 z 4 mm., 10.5 gm. (August 8), ♀, 40912, ovary inactive, 9.5 gm. (August 8), ♀, 40909, ovary inactive, 10.4 gm. (August 9), ♂, 40910, testis 5 × 3 mm., 11.5 gm., molting—1st primaries ensheathed (August 9), and ♂, 40911, 11.5 gm. (August 10), all from {2½}-{3½} km. N San Miguel, Isla Cozumel.