BIRDS OF NORTH AND MIDDLE AMERICA 265 



Juvenal. — Not known. 



Natal down. — Not known. 



Adult male.— Wing 368-385; tail 211.5-216; culmen from cere 



24.7-25; tarsus 83-87; middle toe without claw, 42-43.7 mm. (2 speci- 

 mens including the type). 



Adult female. — Wing 415; tail 232; culmen from cere 29.5; tarsus 90; 



middle toe without claw 50 mm. (1 specimen). 



Range. — Resident in Socorro Island, off the west coast of Mexico. 

 Type locality. — Socorro Island. 



Buteo borealis var. viontanus (not Buieo monlanus Nuttall) Lawrence, Proc. 

 Boston Soc. Nat. Hist., 1871, 42 (Socorro Island, Revillagigedo Group, 

 nw. Mexico), 



Buteo borealis var. costaricensis (not of Ridgway) Lawrence, Mem. Boston Soc. 

 Nat. Hist., ii, 1874, 302 (Socorro Island). 



Buteo borealis socorroensis Ridgway, Proc. U. S. Nat. Mus., iii, 1880, 194, 220 

 (nomen nudum; Socorro Island, Revillagigedo Group, nw. Mexico); Nom. 

 North Amer. Birds, 1881, No. 436 d; in Salvin and Godman, Biol. Centr.- 

 Amer., Aves, iii, 1900, 64 (described!).— Townsend, Proc. U. S. Nat. Mus., 

 xiii, 1890, 135 (Socorro Island). — Nelson, Proc. Biol. Soc. Washington, 

 xii, 1898, 7, in text (Socorro Island). — Brewster, Bull. Mus. Comp. Zool., 

 xli, 1902, 85, part only? (crit.; meas.; spec, from Nicasio, Marin County, 

 Calif., and one from Alamos, Sonora, referred to this subspecies). — Swann, 

 Synopt. List Accip., pt. 2, 1919, 48; Synop. Accip., ed. 2, 1922, 80; Monogr. 

 Birds Prey, i, 1926, 397 (monogr.). — McLellan, Proc. California Acad. 

 Sci., ser. 4, xv, 1926, 297 (Socorro Island; Graysons Cove, Mexico; nest; 

 plumage). 



Buteo socorroensis Gurnet, List Diurn. Birds Prey, 1884, 66; Cat. Birds Prey, 

 1894, 24.— Anthony, Auk, xv, 1898, 316 (Socorro Island).— Sharfe, Hand- 

 list, i, 1899, 256. — Salvin and Godman, Biol. Centr.-Amer., Aves, iii, 

 1900, 64. 



Buteo jamaicensis socorroensis Peters, Check-list Birds of World, i, 1931, 232 

 (distr.). — Housse, El Hornero, viii, 1941, 47, in text (breeding range, on map). 



BUTEO JAMAICENSIS COSTARICENSIS Ridgway 



Central American Red-tailed Hawk 



Adult (sexes ahke). — Similar to that of B. j. borealis, but with the 

 thighs, lower abdomen, and under tail coverts distinctly washed with 

 pale cinnamon; the rectrices averaging paler, never dark hazel, but cin- 

 namon to light orange-cinnamon; the upperparts with little or no 

 rufous spotting; bill black, bluish on basal half of mandible and next 

 to cere; cere and edge of gape waxy greenish yellow; iris brown; tarsi 

 and feet bright yellow; claws black. 



Juvenal (sexes alike). — Similar to that of B. j. borealis, but with the 

 tail pale tawny-cinnamon, not grayish, barred with fuscous-black; 

 with the nape, upper back, and scapulars more spotted with white, 

 and with the thighs heavily spotted with brown, as in some examples 

 of calurus. 



Natal down. — Not recorded. 



