PINE SISKIN 437 



The Juvenal plumage is worn a long time, probably two months 

 according to Dwight (1900), but the exact time is hard to determine 

 because of the irregular breeding season. Rockwell and Wetmore 

 (1914) state that immature birds were still in molt in Colorado the first 

 week in October. They mention young out of the nest July 18, but 

 since the duration of molt is not known, one cannot estimate the time 

 lapse before it began. Winter flocks of incursion visitants usually are 

 preponderantly birds of the year, but this is hardly a clue in inter- 

 preting A. T. Wayne's (1906) comment for the period Dec. 12, 1896, 

 to the following mid-March in South Carolina: "Between these dates 

 many of the birds taken seemed to be in a state of perpetual molt." 



According to Dwight (1900), there is a partial post-juvenal molt 

 in August in eastern Canada involving body plumage but not wings 

 and tail. The first nuptial stage, therefore, is this combination in 

 worn condition. 



Food. — The pine siskin is a tree- and ground-foraging finch. Like 

 the crossbill, it often hangs upside down when feeding in vegetation, 

 but it is a more generaUzed feeder, not tied closely to cone feeding 

 and hence independent of the varying extent of the cone crop. 



The results of food habits analyses were summarized by W. L. 

 McAtee (1926): "The food of the siskin is principally the seeds of 

 coniferous trees, alder, birch, ragweed, and other weeds. About 

 one-sixth of the total food is animal, consisting chiefly of caterpillars, 

 plant lice, scale insects, and grasshoppers. No doubt the siskin pays, 

 in the destruction of these pests, for the forest seeds it consumes." 



Two decades later Dorothy Mierow (1946), having more published 

 information to summarize, wrote: 



They feed their young mainly on aphids and seem quite content with alder, 

 birch, and willow seeds. As they wander farther south and over the plains, their 

 main items of diet may become weed seeds. Farther east, seeds of sweet gum,, 

 maple, and elm, as well as buds and insects, form part of their diet. In Cali- 

 fornia, where they seem to be most numerous, they often feed almost entirely on 

 the seeds of eucalyptus, extracting them from the pods either on the trees or on 

 the ground. They also seek after the sweet liquid in the eucalyptus flowers. 



The following information elaborates on the taking of some of the 

 items already mentioned. Also, in some measure, it indicates seasonal 

 and geographical variation in food habits, plus mentioning some items 

 taken that might not be readily identified in analysis of contents of 

 digestive tracts. 



In early April in Ohio, examination of a siskin revealed it had been 

 feeding on flower buds of the slippery elm (Kemsies, 1948). In June 

 in West Virginia, Maurice Brooks (1943) saw siskins avidly eating 

 the coated carpels of young spruces. Mr. R. E, Mumford WTites of 

 seeing birds feeding on Jack Pine cones (Pinus hanksiana) dm-ing an 

 invasion of Indiana during the winter of 1952-1953. 



