102 University of California Publications in Zoology [Vol. 30 



We visited rock ptarmig^an territory too late to find nests, but from 

 the actions of the birds as we saw them it would seem that the male 

 of this species is not a devoted and constantly attendant mate to the 

 hen, as is notably the case in the willow ptarmigan. The male rock 

 ptarmigans were gathered, two, three, or four together, while the 

 females bore the care of the young alone. Occasionally a female (pre- 

 sumably a non-breeding bird) was seen with several males. On 

 August 8 I did flush a flock consisting of at least one brood of large 

 young ones, and several adult males. This I took to be the beginning 

 of a general flocking together, as might be looked for at the end of 

 the summer. 



The adult male taken on June 9 is still largely in winter plumage, 

 especially below. There are barred feathers on the throat and upper 

 breast, and the back is mostly clothed in summer plumage. Adult 

 males taken during the last week of July and early in August are in 

 summer plumage in as nearly perfect condition as it can probably 

 ever be found, though in all the rectrices are being renewed. In the 

 perfection of this plumage even the abdomen is partly or even entirely 

 clothed in dark-colored feathers, but usually a large white area persists 

 on the lower parts of summer birds. In some specimens old white 

 body feathers are being replaced by new white ones, showing that there 

 is not always an intervening dark summer plumage on parts of the 

 body that are dark on some birds. 



The adult male rock ptarmigan does not seem to go through the 

 stage termed by Dwight (1900, p. 162) "second, or adult, winter 

 plumage (preliminary)," that is so well defined in the willow ptar- 

 migan. I am aware that tl^e contrary has been argued (see, for 

 instance, the account of Lagopws ridgwayi by Stejneger [1885, 

 p. 195] ), but whatever may be the facts as regards other forms of the 

 rock ptarmigan, in British Columbia the male bird of this species does 

 not exhibit two distinct plumages during the summer months. The 

 female does, and the fact that we collected male birds during the period 

 when the females (as well as both sexes of the willow ptarmigan) were 

 molting from one plumage stage to the other, enabled me to make 

 satisfactory comparisons of the different plumages. The first appear- 

 ance of the brown and black barred feathers upon the head, neck, and 

 upper breast in the male rock ptarmigan (early in June in northern 

 British Columbia) is followed so uninterruptedly by the spread of 

 more finely mottled feathers over the rest of the body, that these can 

 hardly be considered as two distinct plumages. Furthermore, the first 



