322 
COLUMBA MIGRATORIA. 
been observed, that the pigeons, when passing' over a 
steril part of the country, keep high in the air ; but 
if, on the contrary, the land is richly covered with food) 
they will fly low, in order to discover the places most 
abundant in food. The form of these migrating bodies 
is an elongated oval, steered by a long, well-plumed 
tail, furnished with well set, and very muscular wings> 
for the size of the individual. If a single bird is seen 
gliding through the woods, and close by, it passes as 
if by magic; and, on trying to see it again, the ey c 
searches in vain — the bird is gone. 
The multitudes of these birds almost pass belief. I® 
the autumn of 1813, Audubon left his house at Hen- 
derson, on the banks of the Ohio, on his wav f® 
Louisville. Having met the pigeons dying from N- E* 
to S.W. in greater numbers than usual, he felt a® 
inclination to enumerate the flocks that would pass 
within the reach of the eye in the course of one hoi®*' 
He dismounted, and, seating himself on a small emi- 
nence, began to mark, in his pocket-book, a dot for eve'T 
flock which passed. Finding, however, that this w* 8 
scarcely possible, and feeling unable to record the flocks 
as they constantly increased, he rose, and, counting 
the dots already put down, found that 103 had be«® 
made in twenty-one minutes. He travelled on, aim 
still met more the farther he wont. The air W 8 * 
literally filled with pigeons; the light of noon-daf 
became dim, as during an eclipse. Whilst waiting f° r 
dinner at the Sun, Audubou saw, at his leisure, immen s ® 
legions still going by, and he says, “ But I canno* 
describe to you the extreme beauty of their aerim 
evolutions, when a hawk chanced to press upon tb® 
rear of a flock. At once, like a torrent, and with * 
noise like thunder, they rushed into a compact ma sS * 
feathers of the tail close together, and closing the wings, they thereby 
render the action of the air predominant on the posterior part o 
the body, which directs the anterior part downwards, and defi vefS 
it over entirely to the influence of gravity. 
The tail can strengthen the action of the wing, by directing 
Itself towards it. 
