Specimen (1): ♂, 40404, testes inactive, 1¾ lb. (July 9), 2 km. S Champotón.
Chondrohierax uncinatus uncinatus (Temminck): Hook-billed Kite.—A pair was seen 5 km. S Champotón on July 8 and 9. Both birds were in adult plumage and appeared to be mated, although we found no nest. The male is referable to C. u. uncinatus on the basis of the narrow white ventral bands, most of which are 0.3 millimeter or less in width. None of the bars exceeds 0.5 millimeter in width. Paynter (1955a) discussed in detail the contradictions in the literature concerning the geographic range of this subspecies, and referred a male in his collection taken in February, 1952, to C. u. aliquonis. Traylor (1941) collected a large series of this species in Yucatán and Campeche in winter and allocated the specimens to the nominate form.
At Pisté, on July 23, a nestling approximately half-grown was brought in by a local boy. The rectrices were partly ensheathed and the feather count extensively downy.
Specimens (2): ♂, 40406, testis 9 × 5 mm., 215.0 gm. (July 10), 5 km. S Champotón; ♂, 40405, nestling, 117.6 gm. (July 24), Pisté.
Buteo magnirostris gracilis (Ridgway): Roadside Hawk.—This was the only hawk seen on Isla Cozumel.
Specimens (2): ♂, 40411, testis 5 mm., 207.3 gm. (August 10), 4 km. N San Miguel; ♀, 40412, 242 gm. (August 10), 3½ km. N San Miguel.
Buteo magnirostris conspectus (Peters): Roadside Hawk.—This species was the commonest hawk on the peninsula and was seen at all localities except Isla Mujeres and Sisal.
Specimens (5): ♂, 40409 (July 12), and ♀, 40410, ova to 1 mm., 249 gm. (July 16), 7½ km. W Escárcega; ♂, 40413, 279 gm. (July 17) 1 km. N, 13 km. W Escárcega; ♂, 40407, testis 5 × 2 mm., 254.7 gm. (July 23), Pisté: ♀, 40408, ovary inactive, 279.0 gm. (July 28), Pueblo Nuevo X-can.
Buteo brachyurus Vieillot: Short-tailed Hawk.—Our one specimen, a male (40414) weighing 342 gm. and in white-bellied phase, was taken by a native 6 km. W Escárcega on July 14. The testes were inactive.
Buteo nitidus plagiatus (Schlegel): Gray Hawk.—Our specimen is one of two subadults sighted near a large milpas, on Rancho San Miguel.