OUR WINTER BIRDS 151 



would not the presence of the Red-headed Woodpecker for two 

 winters be due to the same peculiar causes as lead these other 

 species to stay in small numbers? 



Snowbird 

 J unco hyemalis 

 A comparison of two sets of years, each containing four years, 

 shows much irregularity for the Snowbird. During the first period 

 the total number of records was 60, and for the four last years 

 there were 137 records. Here is something rather hard to explain. 

 Why should there be such a notable difference in the number of 

 records of a common species in the two sets of years? It cannot 

 be that the four first seasons were more severe and the snow 

 more deep. I am inclined to believe that a number of winter 

 species go farther south than our latitude, perhaps very few in- 

 dividuals remaining with us during the severest part of the winter. 

 And when any species is present only in small numbers, it may 

 not be found over a large area. These facts may account for the 

 scarcity of the snowbird during parts of some winters. However, 

 there may be other causes, more or less inexplicable, but none the 

 less certain, that, if known, would account for the irregularity and 

 scarcity of this and other winter species. 



Downy Woodpecker 

 Dryobates pubescens medianus 

 Some interesting figures were obtained for this species in 

 eight winters. The four first show as the total number of records — 

 47, with an average each winter of about 11 records; the four 

 last have a total of 99 records, and an average yearly record of 

 about 24. I could not begin to account for such great disparity 

 in distribution as is disclosed by these figures. Were the weather 

 conditions so different in both sets of years as to cause this notable 

 difference? As already stated in regard to other species, I think 

 not. Neither was it a food question. What then are the possible 

 determining factors in the distribution of the Downy Woodpecker? 

 Well, I have observed that at other seasons of the year this species 

 may often be long absent — why, I cannot say. But this is a fact, 

 and such a thing may occur in winter as well as in spring, let us say. 

 My opinion, then, is that migration is one of the principal factors 

 in the small distribution of this species at certain seasons of the 

 year, winter among them. 



