Living birds can hardly fail to be highly effective agents in the
transportation of seeds. I could give many facts showing how frequently
birds of many kinds are blown by gales to vast distances across the ocean.
We may safely assume that under such circumstances their rate of flight
would often be thirty-five miles an hour; and some authors have given a far
higher estimate. I have never seen an instance of nutritious seeds passing
through the intestines of a bird; but hard seeds of fruit pass uninjured
through even the digestive organs of a turkey. In the course of two
months, I picked up in my garden twelve kinds of seeds, out of the
excrement of small birds, and these seemed perfect, and some of them, which
were tried, germinated. But the following fact is more important: the
crops of birds do not secrete gastric juice, and do not, as I know by
trial, injure in the least the germination of seeds; now, after a bird has
found and devoured a large supply of food, it is positively asserted that
all the grains do not pass into the gizzard for twelve or even eighteen
hours. A bird in this interval might easily be blown to the distance of
five hundred miles, and hawks are known to look out for tired birds, and
the contents of their torn crops might thus readily get scattered. Some
hawks and owls bolt their prey whole, and after an interval of from twelve
to twenty hours, disgorge pellets, which, as I know from experiments made
in the Zoological Gardens, include seeds capable of germination.
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