266 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I50 



MICRASTUR SEMITORQUATUS NASO (Lesson): Collared Forest-Falcon; 

 Halc6n del Monte CoUarejo 



Carnifex iiaso Lesson, £cho du Monde Savant, vol. 6, ser. 2, no. 46, Dec. 15, 

 1842, col. 1085. (Realejo, Nicaragua.) 



A large, long-tailed hunting falcon, inhabitant of dense jungle, with 

 plain (adult) or widely barred (immature) breast. 



Descriptio)!. — Length, 460-560 mm. Adult (sexes alike), upper sur- 

 face brownish black to black, with a line of the same color on the side 

 of the head, and down the base of the foreneck ; upper tail coverts and 

 long tail barred and tipped rather narrowly with white; under sur- 

 face, cheeks, and a narrow collar across the hindneck, either white 

 or cinnamon-buff, the latter varying from pale to dark; under sur- 

 face of wings barred with white and dark brownish gray. 



Immature, crown, side of head, hindneck, and side of neck blackish 

 brown ; rest of upper surface very dark dull brown, with the feathers, 

 including the wing coverts, tipped or barred brokenly with dull buff ; 

 tail and upper tail coverts black, barred and tipped with white as in 

 the adult ; under surface white, or occasionally buffy, barred broadly 

 with brownish black; under surface of wing as in the adult. In an 

 older stage the upper surface is as in the adult, with the breast and 

 sides white or buff lightly streaked with brownish black. 



Dark phase (rare) : In the full stage the entire plumage is dark 

 brownish slate, with narrow, sometimes partly indistinct, bars above 

 and below on the posterior half of the body; varying from this to 

 brownish black above and on foreneck and breast, with dark bars 

 predominating on the rest of lower surface. In these unusual melan- 

 istic plumages the tail has the usual light bars, but with the white 

 obscured, so that they may appear gray. 



An adult male, taken on the Rio Pequeni, had the iris light wood 

 brown ; bare skin around eye, over loral area, and back of cere, dull 

 green ; mandibular rami, and base of maxilla below nostril, also dull 

 green, with a spot of dull honey yellow in the center of the base of 

 the rami ; bare skin across base of gonys, and in center of chin area, 

 also dull honey yellow; rest of bill black; tarsus and toes bright 

 yellow ; claws black. 



Measurements (birds from Mexico, Guatemala, Honduras, and 

 Panama).— Males (7 specimens), wing 251-263 (260), tail 247-275 

 (261.7) ; culmen from cere 19.7-23.2 (21.4), tarsus 85.3-97.4 (88.6) 

 mm. 



Females (4 specimens), wing 270-279 (274), tail 270-288 (281), 

 culmen from cere 23.6-24.1 (23.8), tarsus 86.5-95.0 (90.1) mm. 



