THE ORNITHOLOGISTS AND OOLOGISTS’ SEMI-ANNUAL. 31 
It was probably so named from a certain resemblance in flight to 
several of our hawks with long and pointed wings. And this reminds 
me of the fact that I have seen the Nighthawk and the Sparrow Hawk 
fly for a short distance by flapping the wings alternately. I have nev- 
er seen this mode of flying practiced by any other bird and have nev- 
er seen a note of the habit in any of our Ornithological publications. 
Dr. Coues aptly describes the bird when he calls it a “winged grey- 
hound.’ One of the most remarkable habits of this interesting bird 
is its soaring aloft in the mating season, and dashing to the ground, 
making at the same time a peculiar, hollow, ‘“‘booming noise,” which 
can not easily be described. 
The manner in which this sound is produced has never been satis- 
factorily explained. Some think it is produced by the “sudden expan- 
sion of the mouth while passing through the air” ; others claim just 
as strongly that it is made by the wings. I have formed no opinion 
yet, and it is not probable that we shall soon discover the solution of 
the puzzle. There are good reasons given for accepting either of the 
above theories. 
The Nighthawk builds no nest as a rule. In fact, the few twigs or 
leaves occasionally found can scarcely be said to constitute a nest. 
The eggs are generally laid on the bare ground, sometimes on a sand- 
bar, on the surface of a flat rock, or even on the roofs of the houses 
in a City. 
I have heard and read stories of the Nighthawk carrying their eggs, 
and even young, from one place to another, when their nesting or 
rather hatching place had been discovered. Other birds, the Wood- 
cock, Philohela minor for instance, have the same habit, and it is a 
well known fact that the Wood or Summer Duck, 4zx sponsa carry 
their offspring from the nest, often twenty or thirty feet high, to the 
water’s edge. 
The eggs of this bird are two in number, and are among the most 
variable in color. The ground color varies from creamy-white to a 
stony-gray tint, and they are spotted, blotched, lined and fretted in 
every conceivable way with different shades of gray, brown, stone col- 
or, slate and lilac ; probably no two eggs being exactly the same. 
Unlike the Whip-poor-will, the Nighthawk does not prefer thick 
woods and wet places, choosing rather open, dry sites, with plenty of 
sunlight, which no doubt helps to hatch: the eggs when the parent 
birds are off the nest. 
