ORGANS OF VOICE. 
63 
its affection and interests are awakened by attention to its 
mate, during the time of rearing its young. The male may 
then be generally seen on some twig or bough, at no great 
distance from the nest; in most cases becoming silent if 
aware of a stranger’s approach, or exchanging the note 
of pleasure for another of anger and complaint, which too 
often produces the very evil it dreads. Thus, the Nightin- 
gale, one of our shyest and most timid birds, will frequently 
discover its nest, by making a jarring noise, and also a 
snapping and cracking, at the same time pursuing people 
along the hedges, as they walk, when its young are in a helpless 
state. The male Blackcap is still more incautious, for it will 
commence and continue its song, even when sitting on its 
nest, and thus too frequently become the innocent cause of 
the capture of its brood. 
The loud cries of other birds, however, particularly of 
many of the migratory water-birds, which fly by night, are 
evidently intended for the purpose of keeping them together. 
Few have been without opportunities of listening in the 
silence of the night to the incessant cackling of a flight of 
wild Geese, on their way to some distant spot, high in the 
air. In the Northern seas, sounds of this sort are more fre- 
quently heard, from birds which never come so far to the 
southward. Of these is the red-breasted Diver, which seldom 
quits the water by day, but during the night may be known 
to be on the wing, at a vast height, by a peculiarly melan- 
choly and distressing scream, exactly resembling that of 
a young child suffering from agonizing pain. We have 
listened by the hour together to the repeated and successive 
wailings of these wild, melancholy birds ; first, the scream is 
faint, and so distant as scarcely to reach the ear; then it 
increases as the bird passes nearer, — till, as it continues its 
flight, the sound gradually dies away. Soon another scream 
from another quarter is faintly heard ; and so on, till the dawn 
appears, when they betake themselves to the element on 
which they pass the day. 
The distance, too, at which some birds may be heard is 
very extraordinary. The brown Crane of North America, 
