76 
ORGANS OF VOICE. 
one of our shyest and most timid birds, will fre- 
quently 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 com- 
mence 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, particu- 
larly 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 
frequently 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 melancholy and dis- 
tressing 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 increases as the bird passes 
nearer, — till, as it continues its flight, the sound gra- 
dually dies away. Soon, another scream from another 
quarter is faintly heard ; and so on, till the dawn 
appears, when they betake themselves to the ele- 
ment on which they pass the day. 
