OF ARTS AND SCIENCES. 149 



their flight to chase a passing hawk. Onl}^ a few are seen among 

 the White Mountains after August, though I have noted single 

 stragglers at Intervale so late as September 12, 1900, and in 

 1898, a single bird on September 21, the day being cold, and 

 Mt. Washington's summit white with snov/. 

 Dates : April 24 to September 21. 



193. Tachycineta bicolor (Vieill.). Tree Swai^low. 

 A common spring and fall migrant and less common summer 



resident. These birds arrive in central New Hampshire in 

 early April before the snow is off the ground and from one to 

 three or more pairs are generally found about the smaller towns 

 and villages in summer. At Intervale, I have rarely found 

 more than one pair nesting in the village. In the forest of 

 water-killed trees at the mouth of the Androscoggin River, I^ake 

 Umbagog, Mr. William Brewster ('76b) has recorded that 

 "multitudes" were found "occupying deserted nests of the 

 smaller Woodpeckers." 



Dates : March 23 (Hampton Falls) to September. 



194. Riparia riparia (Linn.). Bank Swallow. 



A common spring and fall migrant and a locally abundant 

 summer resident, nesting in colonies where steep banks of sand 

 occur along the rivers. The breeding birds often go far afield 

 in search of food, and I have frequently seen individuals flying 

 over the Saco valley at least a mile and a half from the nesting 

 colony. It is interesting, in v/atching a large colony, to observe 

 the apparent precision with which each bird enters its proper 

 burrow, and only on rare occasions have I seen a bird hesitate 

 for a second before picking out its own burrow. This is the 

 first of our swallows to leave, and among the White Mountain 

 valleys the breeding colonies break up and disappear by the 

 middle of July, and except on one occasion (a single bird seen 

 Aug. II, 1899) I have never observed the birds at Intervale 

 after July. Mr. William Brewster, however, ('98b) notes them 

 with flocks of other swallows at the lower end of Lake Umba- 

 gog on Aug. 22, 1896. As pointed out by Mr. Ned Dearborn, 

 ('98) these swallows will often dig their burrows in a newly-ex- 



