I saw one nest in July, our coldest month, with
three half-grown young birds in it. They were excessively fat, and,
though it was noon-day, had their crops full. There were three mice and
two young cavies (Cavia australis) lying untouched in the nest.
The short-eared owl is of a wandering disposition, ard performs long
journeys at all seasons of the year in search of districts where food is
abundant; and perhaps these winter-breeders came from a region where
scarcity of prey, or some such cause, had prevented them from nesting at
their usual time in summer.
The gradual increase or decrease continually going on in many species
about us is little remarked; but the sudden infrequent appearance in
vast numbers of large and comparatively rare species is regarded by most
people as a very wonderful phenomenon, not easily explained. On the
pampas, whenever grasshoppers, mice, frogs or crickets become
excessively abundant we confidently look for the appearance of
multitudes of the birds that prey on them. However obvious may be the
cause of the first phenomenon--the sudden inordinate increase during a
favourable year of a species always prolific--the attendant one always
creates astonishment: For how, it is asked, do these largo birds, seldom
seen at other times, receive information in the distant regions they
inhabit of an abundance of food in any particular locality? Years have
perhaps passed during which, scarcely an individual of these kinds has
been seen: all at once armies of the majestic white storks are seen
conspicuously marching about the plain in all directions; while the
night air resounds with the solemn hootings of innumerable owls.
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