IQS SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 150 



Iris dark brown ; eyelids and bare space above dull gray ; bill dull 

 neutral gray at base, shading to dusky neutral gray, or dull black, 

 toward tip ; cere and gape yellow ; tarsus and toes yellow ; claws 

 black. 



Measurements. — Males (4 from Costa Rica, Panama, Colombia 

 and Venezuela), wing 365-394 (378.7), tail 190-205 (199), culmen 

 from cere 20.6-21.5 (21.0), tarsus 66.0-69.0 (68.1) mm. 



Females (6 from Panama, Colombia and Venezuela), wing 385- 

 421 (404.3), tail 197-219 (208.5), culmen from cere 23.4-24.5 (23.8), 

 tarsus 70.6-80.5 (74.8) mm. 



Status not certain. Rare ; 6 specimens known from Panama. 



W. W. Brown, Jr. collected male and female on Isla del Rey 

 on March 6 and 11, 1904 (which are in the Museum of Compara- 

 tive Zoology). A female in the U. S. National Museum was shot on 

 November 9, 1953, on the K-6 Road, near Cerro Galera, Canal 

 Zone. Hasso von Wedel secured a female at Perme, San Bias, August 

 27, 1929 (specimen in the Museum of Comparative Zoology) and 

 two others at Puerto Obaldia, August 14, 1931, and January 13, 

 1932 (now in the Brandt collection at the University of Cincinnati). 



Material that I have seen does not justify separation of the two 

 races that have been recognized in most reports that include this bird. 

 The slaty wash supposed to mark a northern subspecies, in the series 

 seen has been confined to fully adult individuals, as shown by the 

 few broad light tail bands. The blacker individuals throughout the 

 range mainly are those with the narrow, multiple tail bands of the 

 immature. Wing measurements indicate a possible separation, in 

 which there is a larger population in North and Central America, 

 and a slightly smaller one in northern South America. The material 

 seen, however, does not demonstrate this clearly. It is possible that 

 the mixing of larger and smaller individuals found in tropical 

 America is due to an invasion of northern migrants, and that the 

 same mixing in the north may be due to faulty sex determination. 



If two forms are recognized, five of the specimens recorded from 

 Panama, viz., the male (wing 375 mm.) and the female (wing 403) 

 from Isla del Rey, the female (wing 415) from Perme, and the 

 two from Obaldia (wing 394 and 402) appear to come within the 

 smaller, southern group under the name Buteo albonotatus ab- 

 breviatus Cabanis. These might be residents. The fourth, the female 

 from the Canal Zone (wing 421 mm.), which is decidedly larger, 

 then would be regarded as a migrant of typical Buteo albonotatus 

 albonotatus from the north. 



