264 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I50 



grayer than in either of the other two races. This extends from 

 eastern Bolivia and eastern Brazil south to Chaco and Misiones in 

 northern Argentina. 



Size as a distinction between subspecies is not reliable. And the 

 presence of a wash of buff over the white of the head and lower 

 surface that some students have used to separate one supposed race 

 has no value, as this color appears in some specimens in all the 

 groups outlined above. It is found more frequently in wet areas so 

 that the color may be intensified through stain from damp vegeta- 

 tion. 



MICRASTUR MIRANDOLLEI (Schlegel): Slaty-backed Forest-Falcon; 



Halcon Gateador 



Astur mirandollei Schlegel, Mus. Pays-Bas, Astures, 1862 (after Sept.), p. 27. 



(Surinam.) 

 Micrastur mirandollei extimus Griscom and Greenway, Bull. Mus. Comp. Z06I., 



vol. 81, May 1937, p. 418. (Perme, San Bias, Panama.) 



In form the adult suggests the similar stage of the collared forest- 

 falcon, but is smaller, with a shorter tail, dark gray back, and no 

 light band across the hindneck. The immature is marbled with gray 

 and buffy white on the lower surface. 



Description. — Length, 400-450 mm. Adult, dark slate gray above, 

 and on the side of the head ; tail blacker, with tip and 3 narrow bands, 

 sometimes indistinct, of white or buffy white ; below white or buffy, 

 in some lined narrowly with black; under side of wing white or buffy 

 white, barred with dark gray. 



Immature, similar, but with breast and foreneck mottled and lined 

 with dark gray. In some heavily marked individuals a dark gray 

 band crosses the breast. 



An adult male, from Armila, San Bias, shot on March 7, 1963, had 

 the iris verona brown; bare skin on side of head, cere, and base of 

 the bill forward to a point in front of the nostril yellow ; anterior 

 half of bill black ; tarsus and toes yellow ; claws black. 



An immature male, taken at Juan Mina on January 11, 1961, had 

 the iris wood brown ; base of maxilla along cutting edge to level of 

 anterior end of nostril neutral gray; rest dark neutral gray, except 

 the lower half forward of the nostril, and the hooked tip, which, with 

 the lower mandible and gape, were bright yellow; line on side of 

 mandibular rami neutral gray ; free edge of eyelids bright yellow ; 

 rest of bare skin on side of head, including the lores, neutral gray; 

 tarsus and toes bright yellow ; claws black. 



