OF ARTS AND SCIENCES. 59 



The periodical abundance of certain northern birds, such as 

 Pine Grosbeaks, Redpolls, Pine Siskins, and Crossbills, is a 

 phenomenon of no small interest. Such incursions we look 

 upon as irregular and of haphazard occurrence, for no other rea- 

 son, perhaps, than because we are quite ignorant of the condi- 

 tions which bring them about. During the fall and winter of 

 1899- t 900 a notable incursion of Red and of White- winged 

 Crossbills took place not only over New Hampshire, but over 

 most of New England, and the coast regions farther south. 

 The Red Crossbills appeared first, and were already quite com- 

 mon among the hills of New Hampshire during June and July, 

 1S99. During the two mouths following they passed through 

 Massachusetts and made their way to Washington and even to 

 Virginia. The White-wings followed closely in their wake and 

 during the last of October were common in eastern Massachu- 

 setts, passing through during November and December to the 

 states farther south, reaching New Jersey, Pennsylvania and 

 Ohio. It may be of value to place on record a few facts relative 

 to this flight as observed among the White Mountains during 

 the summer of 1899. On June 18, 1899, when I reached Inter- 

 vale, in the Saco Valley, the Red Crossbills were at once no- 

 ticed as abundant. Usually they are present here in small 

 numbers during summer, but on this occasion their numbers 

 were abnormally large. During the remainder of June and ear- 

 ly July, flocks of from seven to twenty were often observed, us- 

 ually flying southward down the river valley in loose order. 

 After the first week or so of July, although they were still pres- 

 sent in about the same numbers, no large flocks were noticed, 

 but at the most little companies of from four to six birds, groups 

 of three, and many pairs and singles. In most cases which 

 could be determined, the paired birds seemed to be adult males 

 and females ; the former were in bright red plumage and fre- 

 quently were observed singing as they flew about on fluttering 

 wing or perched among the tree tops. They seemed to feed to 

 a considerable extent on the seeds of the paper birch, and many 

 were also found feeding among elm trees or upon hemlock seeds 

 in the hemlocks. On two trips into the nearby mountains from 



