DOG-TOWN DIGGINGS 217 
cally protesting at or about something. Cheer- 
fulness and vivacity characterized this fat, 
numerous people, but they were always alert, 
and commonly maintained sentinels scattered 
throughout the town. 
While numbers were visiting or playing a few 
were feeding. They appeared to feed at all 
times of the day. But I do not believe that they 
eat half the food of the average woodchuck. 
The short grass was the principal food. They also 
ate of the various weeds around. I do not re- 
call seeing them eat the bark of sagebrush or 
any part of the prickly pear. 
Prairie dogs must materially assist in soil 
formation. Their digging and tunnelling lets 
dissolving water and disintegrating air into the 
earth and deepens the prairie soil. 
The congesting population in time increases 
the soil supply. In places and for a time this 
new soil seems to be helpful in increasing the food 
supply, but after a time in many towns food 
becomes scarce. Food scarcity causes move- 
ment. I have heard that the entire population 
of a dog town, like an entire species of migrating 
birds, will leave the old town and trek across 
the plains to a site of their liking. 
A generation ago the prairie dog population 
must have exceeded two hundred millions. 
It was scattered over the great plains and 
