THE LIFE OF MAMMALS 
footed ferret, a weasel of the plains, which easily penetrates the burrows, 
and against whose ferocity and skill the squirrels can make little defense. 
Every prairie dog town is also tenanted by many little burrowing owls. 
“ All these conditions together served in the natural state of things to hold 
the prairie dogs in check, but the changes brought about by civilization 
have been so favorable to these little animals, by the reduction 
of their enemies on the one hand, and the augmentation on the 
other hand of their food supplies by the farmers’ plantations of meadow 
grass, alfalfa, and grain, that they have increased into a very serious pest. 
Dr. Merriam stated in the Yearbook of the United States Department of 
Agriculture for rgor that colonies twenty to thirty miles in length were then 
not rare; and one in Texas was known to cover an area of twenty-five hun- 
dred square miles, with a probable average of twenty-five holes to an acre 
and of one animal to each hole. At this rate the prairie-dog population of 
this district would be forty millions; and on the carefully studied estimate 
of students that two hundred and fifty squirrels will devour annually the 
same amount of grass as a cow, the pasturage consumed by this great 
colony would support over 1,500,000 cattle. When such a colony spreads 
over a district devoted to farming, the loss is increased, for the space 
occupied by their mounds is a waste of valuable land; the animals are 
likely to cut irrigation canals, draining off the water, and they devour the 
planted crops, especially of alfalfa. Both the federal government and 
local authorities have tried various methods for relief, but are almost help- 
less in view of the large spaces between cultivated districts, where the pest 
can only be overcome by public and united effort, and also by coéperation 
among the ranchmen. The squirrels may be killed by poison in various ways; 
but best by the use of bisulphide of carbon. A teaspoonful of this cheap 
liquid is placed upon some absorbent substance (a nodule of dry horse 
dung or half a corncob will serve the purpose well), and dropped down the 
hole, which should then be stopped with earth. The fumes are heavy, 
sink into the depths of the burrow, and kill the inhabitants.” 
A Pest. 
These ground squirrels and prairie dogs naturally bridge 
the gap between the tree squirrels and the marmots, as they are 
styled in the Old World, or “ woodchucks,” as we 
know them in the northern states, or ‘ground 
hogs,”’ as they call them in the South. Marmots are of stouter 
build than gophers or susliks, with short, strong limbs, broad 
heads, no cheek pouches, short ears and tail, the first toe of the 
456 
Marmots. 
