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The Naturalist in La Plata.
may be visible to the eye at a vastly greater distance than during fair weather; the sun shining on its intense white plumage against the dark background of a rain-cloud making it exceedingly conspicuous. The fact that swans are almost always seen after rain shows only that they are almost always passing.
Whenever we are visited by a dust-storm on the pampas myriads of hooded gulls--Larus macnlipen-nis--appear flying before the dark dust-cloud, even when not a gull has been seen for months. Dust-storms are of rare occurrence, and come only after a long drought, and, the water-courses being all dry, the gulls cannot have been living in the region over which the storm passes. Yet in seasons of drought gulls must be continually passing by at a great height, seeing but not seen, except when driven together and forced towards the earth by the fury of the storm.
By August (1873) the owls had vanished, and they had, indeed, good cause for leaving. The winter had been one of continued drought; the dry grass and herbage of the preceding year had been consumed by the cattle and wild animals, or had turned to dust, and with the disappearance of their food and cover the mice had ceased to be. The famine-stricken cats sneaked back to the house. It was pitiful to see the little burrowing owls; for these birds, not having the powerful wings and prescient instincts of the vagrant Otus brachyotus, are compelled to face the poverty from which the others escape. Just as abundance had before made
A Wave of Life. 67
the domestic cats wild, scarcity now made the burrowing owls tame and fearless of man. They were so reduced as scarcely to be able to fly, and hung about the houses all day long on the look-out for some stray morsel of food. I have frequently seen one alight and advance within two or three yards of the door-step, probably attracted by the smell of roasted meat. The weather continued dry until late in spring, so reducing the sheep and cattle that incredible numbers perished during a month of cold and rainy weather that followed the drought.