28 
A STUDY OF THE CANADIAN RACES OF ROCK PTARMIGAN 
(Lag opus rupestris) 1 
By P. A . Taverner 
In studying the specimens collected by J. D. Soper for the National 
Museum of Canada in Baffin island (Pangnirtung, lake Nettilling, and cape 
Dorset) it became evident that two forms of rock ptarmigan were repre- 
sented in our general collections. One, decidedly yellow or ochraceous, of 
more northern range; the other greyish and less yellow, of more southern 
distribution. Reference to literature indicates that little has been written 
regarding the rock ptarmigan of the main continental mass or of the 
islands to the north of it. Most authorities have been content convention- 
ally to assume that the bird of the eastern Arctic islands and Greenland 
was reinhardi and that of the mainland was rupestris, with welchi, under 
full specific standing, restricted to Newfoundland. The material under 
survey did not seem to satisfy this hypothesis. The most recent author to 
study the species is H. S. Swarth 2 , but neither do all his conclusions agree 
with the facts presented by the new material. It seemed advisable then to 
make as thorough a study of the species as was possible. 
Written description unaccompanied by identified specimens is a most 
unsatisfactory guide to the determination of the various ptarmigan races, 
and it was evident that little could be done with the material without 
approximate topotypes of the accepted races. Attempts to borrow such 
specimens revealed a most surprising dearth of them in collections. Through 
the courtesy of other museums 3 considerable pertinent material was 
obtained, though on assembling all the fragmentary nature of the data 
is evident. The presence of a northern yellow race is generally substanti- 
ated, but the picture is obscured by lack of definite outlines and dis- 
turbed by the unexplained sporadic occurrence of typical specimens far 
from what would seem to be their proper range. 
The comparison of rock ptarmigan plumages is an exceedingly difficult 
process. The white winter plumages are practically useless for subspecific 
determination. The sexes in summer are dissimilar and, besides the 
juvenile, each have two distinct plumages that, crowded into the short 
northern season, are decidedly evanescent. It is unusual that either of 
these plumages is presented in completeness. They blend one into the 
other and the birds seem in continuous moult throughout spring, summer, 
and autumn, and masses of early plumage persist through later ones. It 
1 In view of the large amount of individual, sexual, seasonal, and adventitious variation in the 
Bpecies, the consequent large series of specimens necessary for successful study of the races and 
the paucity of extralimital material available, it does not seem worth while to attempt comparison 
between New and Old World forms at this time. Therefore, the relationship between Lagopus 
rupestris and Lagopus mutus has not been touched upon in this review. As a matter of convenience 
and without prejudice to the contrary, it is assumed that the North American species is Lagopus 
rupestris. 
2 “Birds of Atlin District, British Columbia”; Univ. Cal. Pub. in Zool., vol. 30, No. 4 (1926). 
* Museum of Comparative Zoology, Cambridge, Mass.; Museum of Vertebrate Zoology, 
Berkeley, Cal.; U.S. National Museum, Washington, D.C.; American Museum of Natural 
History, New York; Public Museum of the City of Milwaukee, Milwaukee, Wis.; Academy of 
Natural Sciences, Philadelphia, Pa.; and the Carnegie Museum, Pittsburgh, Pa. To these institu- 
tions and their curators we desire to express our thanks. 
