_Dendroica petechia bryanti_ (Ridgway): Yellow (Mangrove) Warbler.-- Previous records of breeding by this species are available for March 29 and 30 and May 16 (Paynter, 1955a:247). Breeding apparently continues at least into July. An adult male with moderately enlarged testes (probably regressing) was taken on July 7 at Zacatel, Campeche, and a juvenile was obtained 13 km. WSW Sisal on August 10. The male at Zacatal was in mangroves alongside the ferry landing (for the ferry from Isla del Carmen) and seems to be the first specimen of this subspecies recorded for the state. Specimens (7): [Male], 40829, testis 4 × 2 mm., 11.1 gm., molting--1st, 2nd, and 3rd primaries ensheathed (July 7), Zacatal, Campeche; [Male], 40823, imm., 10.0 gm. (August 9), [Male], 40824, testis 1 mm., 13.0 gm., molting--4th and 5th primaries and middle three rectrices ensheathed (August 9), [Male], 40826, juv., 10.1 gm. (August 10), [Male], 40827, imm. (fresh, first winter plumage), 10.2 gm. (August 10), sex?, 40825, 10.3 gm. (August 10), and [Male], 40828, testis 2 mm., molting--7th, 8th, and 9th primaries, 2nd, and 3rd secondaries and outer pair of rectrices ensheathed (August 11), all from 13 km. WSW Sisal. _Seiurus motacilla_ (Vieillot): Louisiana Waterthrush.--Our specimen, apparently an early migrant, was taken near the aguada at Rancho San Miguel. Specimen (1): [Male], 40835, testis minute, 19.9 gm. (August 14), 4 km. NNE Felipe Carrillo Puerto. _Tangavius aeneus aeneus_ (Wagler): Red-eyed Cowbird.--A male having enlarged testes taken on August 14 seems to be the first record of breeding in the species for the peninsula. Specimens (2): [Male], 40838, testis 11 × 7 mm., 66.9 gm. (August 14), and [Female], 40839, ovary 6 mm., 60 gm. (August 15), 4 km. NNE Felipe Carrillo Puerto. _Cassidix mexicanus_ (Gmelin): Boat-tailed Grackle.--Specimen (1): [Male], 40840, 223.3 gm. (July 9), 1 km. SW Puerto Real, Isla del Carmen. _Dives dives dives_ (Deppe): Sumichrast Blackbird.--This species previously has been known to breed in May (Paynter, 1955a:263). The specimens from July had moderately active ovaries. Specimens (2): [Female], 40842, ovary 8 × 4 mm., 92 gm. (July 11), 5 km. SW Champotón; [Female], 40841, ovary 11 × 5 mm., 88.6 gm. (July 21), Pisté. _Icterus prosthemelas_ (Strickland): Black-cowled Oriole.--Specimens (2): [Female], 40843, ovary 5 × 3 mm., 28.8 gm., molting--extensive body molt, 1st, 2nd, and 3rd primaries ensheathed (August 3), 4 km. WSW Puerto Juarez; [Male], 40844, testis 2 × 1 mm., 31.0 gm., molting 1st, 2nd, 3rd, and 4th primaries ensheathed (August 16), 4 km. NNE Felipe Carrillo Puerto. _Icterus mesomelas_ (Wagler): Yellow-tailed Oriole.--Our specimens extend the known breeding season; previous records are for April and May (Paynter, 1955a:265).