One of these flocks dropped from the invisible regions to
the lawn on the river bank on which I stood. Without exaggeration I may
say that I saw them fall from the sky, for I was looking upwards, and saw
them when first visible as descending specks. The plunge was perpendicular
till within ten yards of the ground. Soon the high-flying crowds of birds
drew down, and swept for a few minutes low over the willows, from end to
end of the eyot, with a sound like the rush of water in a hydraulic pipe.
Then by a common impulse the whole mass settled down from end to end of
the island, upon the osiers. Those in the centre of the eyot were black
with swallows--like the black blight on beans.
Next morning, at 6.30 a.m., every swallow was gone. In half an hour's
watching not a bird was seen. Whether they went on during the night, or
started at dawn, I know not. Probably the latter, for Gilbert White once
found a heath covered with such a flock of migrating swallows, which did
not leave till the sun dispelled the mists.
The migration routes of birds follow river valleys, when these are
conveniently in line with the course they wish to take. There is far more
food along a river than elsewhere, and this is a consideration, for most
birds, in spite of the wonderful stories of thousand-mile flights, prefer
to rest and feed when making long migrations, and also those short shifts
of locality which temporary hard weather causes.
Pages:
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86