Be Bulletin American Museum of Natural History. [Vol. XXXIV, 
REMARKS ON CERTAIN SoutTH AMERICAN FORMS OF THE GENUS 
CERCHNEIS. 
In identifying our large collection of Colombian Sparrow Hawks, I was 
led also to take up specimens of this bird which we have recently received 
from Ecuador, Peru and Chile. This necessarily widened my survey of the 
group and without attempting a revision of its South American members, 
I present here merely the conclusions reached in naming the specimens 
contained in our collections. 
I have seen no specimens of Cerchnets sparverius brevipennis Berl.,' 
C’. s. distincta Cory,’ or C. s. margaritensis Cory.’ 
The numerous forms of Cerchnets sparverius 4 appear to fall naturally 
into three main geographic divisions, North American, West Indian, and 
South American. The West Indian division, represented by Cerchneis 
sparvertus antillarum, is more strongly differentiated from both the North 
and South American types than, generally speaking, they are from each 
other. The male has the underparts more heavily spotted than in any other 
form, except the insular C. s. fernandensis, the wing-coverts strongly marked 
with black, and the tail feathers, including the central pair, more or less 
barred with black. The female is strongly barred with black above and 
has the markings of the underparts blacker than in any other form exam- 
ined. All the specimens in my small series of this race (three males, five 
females) have the crown largely rufous. This fact, in connection with the 
occasional presence of small black markings on the central rectrices in 
North American specimens, suggests that antillarwm is more closely related 
to the North American than to the South American group. 
The North American group extends as far southward as the Canal 
Zone in Panama whence we have a pair of birds which I refer to Cerchneis 
sparvertus sparvertus. I also provisionally refer a female in worn plumage, 
taken December 29, 1911, at Noanama, western Colombia, to this race. 
There are no characters by which members of the North American group 
can always be distinguished from members of the South American group. 
The former, however, practically always have the crown with a more or less 
well developed rufous patch, while males of the latter are usually without 
rufous in the crown, or, if it be present, it occupies in both sexes a much 
smaller area than in North American specimens. . 
1 J. f. O., 1892, p. 91 (Curacao). 
? Field Mus. Pub. 182, 1915, p. 297 (Boa Vista, Rio Branco, Brazil). 
3 Ibid., p. 297 (Margarita Island). 
* Omitting here Cerchneis dominicensis of Cuba, Hayti and Santo Domingo. 
