66 The Naturalist in La Plata. 



may be visible to the eye at a vastly greater dis- 

 tance than during fair weather; the sun shining 

 on its intense white plumage against the dark back- 

 ground of a rain-cloud making it exceedingly con- 

 spicuous. 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 maculipen- 

 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 drj^ 

 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 



