Alexander Wilson, the pioneer American ornithologist, was the man who
seriously endeavored to estimate by computations the total number of
passenger pigeons in one flock that was seen by him. Here is what he has
said in his "American Ornithology":

"To form a rough estimate of the daily consumption of one of these
immense flocks, let us first attempt to calculate the numbers of that
above mentioned, as seen in passing between Frankfort and the Indiana
territory. If we suppose this column to have been one mile in breadth
(and I believe it to have been much more) and that it moved at the rate
of one mile in a minute, four hours, the time it continued passing,
would make its whole length two hundred and forty miles. Again,
supposing that each square yard of this moving body comprehended three
pigeons; the square yards in the whole space multiplied by three would
give 2,230,272,000 pigeons! An almost inconceivable multitude, and yet
probably far below the actual amount."

* * * * *

"Happening to go ashore one charming afternoon, to purchase some milk at
a house that stood near the river, and while talking with the people
within doors, I was suddenly struck with astonishment at a loud rushing
roar, succeeded by instant darkness, which, on the first moment, I took
for a tornado about to overwhelm the house and every thing around in
destruction. The people observing my surprise, coolly said, 'It is only
the pigeons!' On running out I beheld a flock, thirty or forty yards in
width, sweeping along very low, between the house and the mountain or
height that formed the second bank of the river. These continued passing
for more than a quarter of an hour, and at length varied their bearing