42 DIVISION I. VERTEBRAL ANIMALS.— CLASS II. AVES. 
flue of a chimney ; but, before the country was settled, they bred, and we have 
no doubt that great numbers of them, in thinly-settled districts, still breed, 
in hollow trees. The nest is composed of twigs, which are glued together, 
and to the side of the chimney, with the saliva of the bird. It is lined with 
a few feathers and straws. The strength of these structures is wonderful, 
and they are so durable that we have known of instances of their remaining 
in the chimney during three seasons. Usually the bird displays great 
sagacity in the choice of a location for a nest, in securing protection from 
storms and from the attacks of animals; but occasionally the nest is built in 
a chimney, open at the top sufficiently wide to permit the rain to trickle 
down the sides: the result is, that the moisture softens the glue by which 
the nest is attached to the chimney, and it is, with its living contents, pre- 
cipitated to the bottom. Again, if the nest is built too low in the chimney, 
the young or eggs furnish agreeable food for rats, which, unfortunately, are 
sometimes found in dwelling-houses in the country in uncomfortable num- 
bers. The eggs are generally four or five in number, pure white in color, 
rather long in shape. 
From earliest dawn 
until seven or eight in the morning, it is busy in the pursuit of insects: it 
This species is somewhat nocturnal in its habits. 
then retires to its roosting-places in the chimneys, and is seldom seen until 
late in the afternoon. From early twilight until late in the night it is again 
actively employed ; and, having heard its notes, as it sped through the air, 
often as late as midnight, we have no doubt that, in pleasant weather, it is 
busy through the whole night. 
In descending the chimneys, where their young are, the birds fly rapidly 
until they are immediately over them, when, partially closing their wings, 
they drop suddenly, and with apparent ease, down the flue. In ascend- 
ing, the noise of their wings in the chimney is like that of a distant 
thunder. The flight of these birds is very rapid, surpassing, we think, 
that of any other species: it is so peculiar, —the long wings vibrating in 
short, quick, energetic strokes, —that it furnishes a ready means of dis- 
tinguishing it from all other species at a great height. 
About sunset the ereat multitudes of these birds are out, and the num- 
bers of insects they destroy must be immense. Everywhere they may be 
seen: away up in the blue sky, as far as the eye can reach, they are coursing 
in wide-extended circles, chasing each other in sport, and even caressing and 
feeding their mates while on the wing; a little lower, they are speeding 
over the tops of trees, leaning the insects that have just left the foliage ; 
over the surface of the lake or river they fly so low, in the pursuit of aquatic 
insects, that their wings often touch the water: everywhere they are busy. 
Truly, they are deserving of much better treatment than they too often re- 
