TREE SWALLOW 385 



grounds in the Northern States. It is a hardy species; many indi- 

 viduals spend the winter in the southern part of the United States 

 and hence have a comparatively short niigi^ation to their summer 

 homes. As they press northward, arriving in New England often 

 late in March, they may encounter frost and snow, for at this season 

 the advance of spring is very variable here. Under such conditions 

 ihey often disappear for a time, and it is supposed that they retreat 

 until spring steps northward again. 



It is interesting to watch these early arrivals when caught by un- 

 favorable weather. As an example of their resourcefulness, Richard 

 J. Eaton (MS.) relates the following account: "On the morning of 

 March 19, 1939, G. W. Cotterell and I closely observed three tree 

 swallows feeding on the ice on Heard's Pond, Wayland, Mass. The 

 fields were blanketed with hard, crusty snow. The day was sunny 

 and calm, the temperature slightly below freezing in the shade. We 

 first saw the birds from a distance, flying back and forth over a 

 restricted portion of the old white ice. The entire pond and the 

 flooded meadow between it and the Sudbury River were frozen 

 tight. We hitched ourselves (in a sitting position) to within 10 feet 

 of the feeding swallows. Watching at this close range, we could 

 see that they were feeding on what looked like seeds frozen to the 

 surface of the ice in long windrows or irregular bands about 20 

 yards from shore. Maneuvering within a few inches of the ice in 

 a zone about 30 feet long, they picked up the food while they were 

 on the wing, making an audible clicking sound with their bills when 

 pecking at the seeds. The swallows had discovered that a vigorous 

 dig with the bill was necessary to dislodge the seeds. They accom- 

 plished this with an emphatic downthrust of their heads without 

 interrupting their somewhat deliberate flight. Frequently the birds 

 rested on the ice for a few seconds and occasionally pecked at the 

 food in this position, like very young chickens. 



"These swallows seemed to be plump, vigorous, and in good con- 

 dition. After they left we carefully inspected the ice where they 

 had been feeding and found an abundance of seeds, chiefly Scirpus 

 and Carex. We discovered no living animal matter — not even snow 

 fleas." 



Walter Faxon and Ralph Hoffmann (1900) speak of conspicuous 

 flights of tree swallows in Berkshire County, Mass. They say : "Vast 

 numbers collect at the head of Pontoosuc Lake during the vernal mi- 

 gration, where we have seen them take their departure for the north 

 as late as the 22d of May. After sitting toward the close of day 

 upon the low bushes that protrude above the surface of the lake, 

 at half past seven o'clock, myriads at once soared into the air, part- 

 ing to form two flocks, one of which took a course due north, while 

 the second struck off to the W.N.W." 



