310 LAND-BIRDS. 



Boston and other cities, where they have been found to lay 

 their eggs on flat roofs. They are probably more abundant 

 in northern New England than in Massachusetts, in some 

 places forming large colonies. Near Wilson's MiUs in Maine, 

 says Mr. Samuels, " in the space of every four or five rods, a 

 female was sitting on her eggs." Both Wilson and Audubon 

 speak of the female's endeavors, when frightened during incu- 

 bation, to lead the intruder away by feigning lameness and dis- 

 tress. In this case, though less so than with many other birds 

 who build no nest, it is difficult to find the eggs. If these be 

 left undisturbed when found, they are sometimes removed, 

 very probably in the capacious mouths of their j^arents, as 

 Audubon states to be the case with the Chuck-will' s-widow. 

 The Night " Hawks," like the Whippoor wills, perch length- 

 wise, but unlike them frequently utter their notes on wing. 



d. Their ordinary note is peculiar and indescribable, 

 though I have heard it well imitated by the human mouth. 

 It is usually called a loud, harsh squeak, but I know no 

 sounds like it, except the notes of one or two other birds. It 

 is very striking, and, if heard from a near standpoint, rather 

 startling. The male Night " Hawk" produces an equally ex- 

 traordinary sound, which is heard chiefly during the season of 

 courtship. Mounting to some height, he falls, head foremost, 

 until near the ground, when he checks his downward course, 

 and then the " booming " is heard, a sound " resembling that 

 produced by blowing strongly into the bung hole of an empty 

 hogshead." I am uncertain as to what causes this noise, hav- 

 ing found it impossible to make any close observations. Wil- 

 son thought it produced by the mouth ; Audubon, by the con- 

 cussion caused by a change of position in the wings. The 

 Night " Hawks " all leave New England in September. 



§ 21. CYPSBLID^. Swifts. (See § 20.) 



I. CHiETURA. 



A. PELAGICA. Chimney Swift. Chimney " Swallow.'' 

 A common summer resident throughout New England.* 



* There are probably few if any the southern and eastern coasts to the 

 square miles in all New England, from northern and western frontiers, which 



