172 . THE BIRDS 
chimneys, I will state that a piece of tin turned up about 
one inch around the edge, like an inverted box cover, is 
fitted to a garden hoe. On the inside of this cover is 
glued a layer of cotton, on to which roll any eggs possibly 
falling from the nest when detaching it from the side, 
after the hoe is lowered down the chimney and under the 
nest. The nest is made of dead twigs, snatched or 
broken off from the extremity of some limb as they fly 
by, the birds pausing only a second, seemingly, to perform 
this act. The twigs are glued together by a sticky hquid 
from the bird’s mouth, into a slightly hollowed semi- 
circular structure, the same sticky substance attaching it 
to the inside of the chimney. I have noticed that they 
seldom use a chimney that has a thick coating of soot on 
the inside, the reason, I presume, being that it tends to 
fall off in chunks during the summer. Nor do they like 
new buildings with chimneys without some soot in them. 
There are many large hollow cypress trees still’ in the 
Dismal Swamp where these birds may be found breeding 
in their natural haunts. Between sundown and twilight 
during the summer, these birds are seen at their best in 
small flocks of from three to six in number, sailing 
together closely one behind the other in large circles, 
uttering a trilling whistle as though made by their wings. 
During migration often countless numbers descend for the 
night like a huge funnel into some large single chimney or 
group of chimneys. Only one brood is raised with us a 
season. The height of the fall migration southward is 
about September 2nd. During the season of 1912 an extra 
large flock of migrating swifts passed southward as late 
as October 5th. They do not winter with us, arriving 
April 7th to 10th. Their food, taken entirely when on 
the wing, consists wholly of insect matter, many of which 
are still alive when fed to the young. 
