Myiopagis veridicata (Vieillot): Yellow-crowned Elaenia.—The only previous breeding record is of a male that was taken on April 29. My only specimen has nearly fully enlarged testes.
Specimen (1): ♂, 40688, testis 7 × 4 mm., 13.1 gm. (July 17), 1 km. N, 13 km. W Escárcega.
Progne subis subis (Linnaeus): Purple Martin.—A large migrant flock of several thousand individuals of this species was present for several days in August at Rancho San Miguel.
Specimens (3): ♀, 40723, ovary inactive, 48.6 gm. (August 14), ♀, 40724, 51.8 gm. (August 17), and ♀, 40725, imm. skull, 52.1 gm. (August 17), 4 km. NNE Felipe Carrillo Puerto.
Petrochelidon fulva citata Van Tyne: Cave Swallow.—Throughout our stay at Pisté, large numbers of Cave Swallows were seen flying in and out of the small opening of a well-like cenote in the center of the village. Specimens were easily collected in a mist net placed across the opening. No young Cave Swallows were taken and gonads of adults were in various stages of reproductive activity. A few individuals taken were beginning to molt. Probably the swallows were nesting in the cenote although the nests were inaccessible to view. Previous breeding records are for April (Paynter, 1955a:209).
Twenty-two specimens were collected, of which the following were taken at Pisté, July 21-25: ♂, 40693, testis 6 × 3 mm., 18.4 gm.; ♂, 40696, 16.4 gm.; ♀, 40697, 18.2 gm.; ♂, 40695, 15.0 gm.; ♀, 40690, ovary inactive, 18.4 gm., molting—2nd primaries ensheathed; ♂, 40692, testis 5 × 3 mm., 17.9 gm.; ♀, 40698, 18.3 gm.; ♀, 40702, ovary 7 × 3 mm., 18.9 gm.; ♀, 40703, ovary 6 × 3 mm., 17.5 gm.; ♂, 40713, testis 3 mm., 18.4 gm.; ♀, 40704, 16.5 gm.; ♂, 40705, 20.3 gm.; ♂, 40699, testis 2 mm., 18.6 gm., molting—2nd primaries ensheathed; ♀, 40700, ovary 5 × 3 mm., 18.5 gm., molting—1st primaries ensheathed; ♀, 40701, ovary 5 × 3 mm., 16.5 gm., molting—1st primaries ensheathed; ♂, 40707, testis 7 × 5 mm., 19.9; ♂, 40708, testis 4 × 3 mm., 18.4 gm.; ♀, 40709, ovary 4 × 3 mm., 18.0 gm.; sex? 40711, 18.3 gm., molting—1st and 2nd primaries ensheathed.
Additional specimens are: ♀, 40718, 16.5 gm., molting—3rd primaries ensheathed (August 16), and ♀, 40719, 18.5 gm., molting 1st primaries ensheathed (August 16), 4 km. NNE Felipe Carrillo Puerto; ♂, 40689, testis 1 mm., 16.2 gm., molting—2nd primaries ensheathed (August 10), 13 km. WSW Sisal. Mallophaga: Philopterus excisus, July 21; Myrsidea sp. July 21 and 25.
Stelgidopteryx ruficollis Audubon: Rough-winged Swallow.—Previous records indicate that three subspecies of this species occur on the Yucatán Peninsula (Paynter, 1955a:209). One of these, S. r. ridgwayi, is resident. S. r. serripennis, representing the breeding population occurring from British Columbia and New Hampshire over much of the United States to central California, central Texas, and the Gulf states, has been taken on the peninsula in winter. Paynter referred two specimens taken in late September and three January-taken specimens to S. r. stuarti, the highland race that breeds from the mountains of southern Veracruz to Guatamala.
Allan R. Phillips had identified two immature individuals (40694 and 40712) from Pisté as S. r. stuarti; one specimen from Puerto Juarez also is an immature and is nearly identical to those from Pisté. Two adults from Pisté (40691 and 40710) are noticeably darker dorsally than the immatures but are molting extensively and their identification to subspecies is equivocal. Two other adults (40706 and 40715) were prepared as skeletons.
Although mid-July seems early for S. r. stuarti to be present on the peninsula it is not too surprising since the three specimens positively identified are immature birds and young possibly arrive earlier than do adults. But, the immature specimens possibly are atypical individuals of the resident population of S. r. ridgwayi.