Sunday, July 29, 2007

Rats March Like Soldiers


Rodents Have Little Difficulty in Finding Supply of Food, and Adapt Themselves to Conditions

The ready adaptability of rats to their surroundings is one of the qualities which has enabled them to conquer the world, E. W. Nelson writes in the National Geographic magazine. On the approach of warm weather in summer, large numbers of them leave buildings and resort to fields on farms or to the outskirts of the towns, where the growing vegetation, particularly cultivated plants, affords them an abundant supply until the approach of winter. At the beginning of cold weather they return again to the shelter of buildings, where they find the harvested crops ready for their consumption.

When the food supply suddenly decreases following a period of plenty during which the rats have greatly increased in numbers, a migratory impulse appears to affect the entire rat population over large areas and a general migration takes place. At such times the rats are extraordinarily bold, swimming rivers without hesitation, and surmounting all other natural obstacles. The first invasion of Europe, when rats swam the Volga, was an instance of this kind. Experiments by the United States public health service have shown that when released in the water of a harbor rats may swim ashore for a distance of 1,500 yards.

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