670 BULLETIN 5 0, UNITED STATES NATIONAL MUSEUM 



Falco peregrinus Mtjnro, Can. Joiirn. Res., D, xxiii, 1945, 56 (Cariboo Parklands, 



Brit. Columbia; occas.). 

 Falco gyrjalco (not of Linnaeus) Dall, Proc. California Acad. Sci., 1874, 3 (Kiska 



Island, Aleutians; habits). — Ridgway, Amer. Nat., viii, 1874, 434 (Kiska 



Harbor; descr. adult female). 



Subgenus Neofalco Ridgway 



Small to medium-sized falcons (wing about 180-250 mm.) similar 

 in structural details to Falco, but with nostril relatively much smaller, 

 tarsus with less than upper third feathered in front, tip of tail truncate 

 or slightlj'' emarginate (instead of rounded), and coloration of young 

 not materially different from that of adults. 



Bill moderate in size, its depth at rhamphotheca about equal to its 

 width at same point and very nearly equal to distance from anterior 

 margin of cere (in front of nostril) to tip of maxilla; culmen strongly 

 decurved from base, distinctly but not sharply ridged; gonj^s slightly 

 convex, ascending terminally, obviously, but not distinctly, ridged 

 (in F. albigularis) or broad and smoothly rounded (F. deiroleucus) ; 

 maxillary tomium with "tooth" and sinuosities moderately developed, 

 the mandibular tomium with subterminal notch relatively very large; 

 sides of maxilla swollen subterminally, the tip (unguis) rather abruptly 

 contracted or compressed. Nostril relatively small, circular. Wing 

 long and pointed, the longest primary exceeding distal secondaries 

 by much more than half the length of wing; second primary (from 

 outside) longest, the first (outermost) much longer than third; outer- 

 most primary, only, with inner web emarginated, the emargination 

 between tips of fourth and fifth primaries; second primary, only, 

 Nvith outer web slightly sinuated. Tail decidedly less than half as 

 long as wing, truncate or even slightly emarginated, the rectrices (12) 

 very rigid, relatively rather narrow, the middle pair slightly tapering 

 terminally. Tarsus decidedly longer than middle toe without claw 

 (F. albigularis) to decidedly shorter (F. deiroleucus), with less than 

 one-third of its upper portion feathered in front oiily, covered else- 

 where with small roundish or hexagonal scales, these largest on inner 

 side of acrotarsium, smallest on planta tarsi; outer toe, without claw, 

 reaching to slightly beyond penultimate articulation of middle toe 

 and much beyond end of inner toe; hallux, ^\'ithout claw, about as 

 long as basal phalanx of middle toe, its claw nearly as long as the 

 digit. 



Plumage and coloration. — Plumage compact, the primaries and 

 rectrices (especially the latter) rigid; orbital region bare to a much 

 less extent than in Falco. Adults (sexes alike in coloration) with 

 head (except chin and throat) and upperparts black, the feathers of 

 rump, upper tail coverts, scapulars, and wing coverts more or less 

 distinctly margined terminally with slate-gra}^, the tail with transverse 



