Some Results of Bird-Lore's Christmas Bird Censuses 17 



Chickadee (80%). 



Downy Woodpecker (5Q%)- • ■ I 



White-breasted Nuthatch (51%) 



Brown Creeper (35%) 



Redpoll (17%). 



Pine Siskin (12%). 



FIG. IV. PERCENTAGE OF REPORTS 

 CONTAINING SPECIES. (1901-1911) 



Red-breasted Nuthatch (io<^). 



Pine Grosbeak (6%). 



Red Crossbill (4%) . 



White-winged Crossbill (4%) . 



as a rule, only slight changes from year to year. The Creeper, which is the 

 most migratory of the three, shows the smoothest curve. 



The curves of the boreal birds, on the other hand, are very irregular. The 

 Red-breasted Nuthatch and the Crossbills for a series of winters appear and 

 are absent on alternate years. The Pine Grosbeak, as a rule, seems to appear 

 in abundance after every two years of absence. The curves of the Pine Siskin 

 and Redpoll are remarkable for the great waves of 1908 and 1909, respectively. 

 1908 was one of the 'bird winters.' Southern birds were common north of 

 their normal winter range, while, for some reason, boreal birds came south in 

 greater numbers than usual. This was the year of the Siskin wave, but it was 



