534 PBOCiEEaDINGS OF THE NATrO'N)A3L MUSEIUM vol.89 



Identification of these specimens and some others obtained since in 

 southeastern Mexico has led to careful examination of a large series 

 of sparrow hawks from North America with the result that I have 

 been forced to the conclusion that all north of the ranges of FaJco s. 

 paulus of the extreme southeastern United States and Falco s. penin- 

 sularis of the lower half of Baja California must be called Falco s. 

 sparverius. 



Laid out in series it may appear at first glance that birds from the 

 eastern part of North America are darker than those from the west, 

 a distinction that has been recognized for years by calling these west- 

 ern birds Falco s. phalaena. The darker color seems most evident in 

 females, less so in males. On critical examination, however, it 

 appears that the difference in color does not hold for enough indi- 

 viduals to allow a subspecific designation, as many eastern birds are 

 pale and many western ones dark. There is no appreciable differ- 

 ence in dimensions between birds from the two areas. 



In making comparisons examination has been made in turn of 

 breeding series, of a large number of specimens in fresh plumage 

 taken in fall, winter, and spring, and finally of a considerable num- 

 ber of immature individuals recently from the nest. These latter, 

 though averaging decidedly darker, show the same variations as the 

 adults without regard to geographic locality. Birds in fresh plumage 

 are ordinarily darker than those taken toward the middle of the 

 breeding season, and I believe that the lighter color of many indi- 

 viduals is due to actual fading, particularly of the reddish brown 

 that is so prominent in the plumage of these falcons. Naturally this 

 fading is more pronounced in sections of small rainfall where the 

 light is more intense, and less so in more humid areas where the 

 light is more diffused. The exposed perches frequented by these 

 hawks favor this process and through it the birds would naturally 

 become paler quickly in the sun of the arid areas of the southwest. 



There is a distinct tendency toward dichromatism in this race in 

 that many are erythristic, i. e., the reddish brown is intensified, and 

 in the male suffuses the light band at the tip of the tail, which in 

 others is white. Such a condition is well known in some of the trop- 

 ical races. The chestnut crown cap is large, small, or absent without 

 regard to locality. 



Family PHASIANIDAE 



DENDRORTYX LEUCOPHRYS NICARAGUAE Miller and Griscoin 



Dendrortyx leucopUrys nicaraguae Miller and Griscom, Amer. Mus. Nov., No. 

 183, July IS, 1925, p. 1 ( Jalapa, 4,000 feet elevation, Nicaragua) . 



During my stay at the hospitable Sierra Santa Elena there was 

 much talk of the elusive guachoque^ as these long-tailed, forest- 



