THE PRAIRIE DOG OF THE GREAT PLAINS. 
259 
their tails and chattering or h)arking excitedly. If he continues to 
move to^ ard them the excitement increases, and most of the animals 
on the near side of the colony plunge headlong into their burrows. 
Some withdraw more slowly, and for some time their heads and e3'es 
may be seen peering up from the funnel-shaped openings of the mounds. 
Those near by are usually silent, while those at a little distance con- 
tinue to scold and chatter. This chattering or barking, as it is usually 
called, can often be heard after the animals have gone down out of sight 
in their holes. (PL XXII.) 
Along railroads the animals have become so accustomed to tne trains 
that the}^ no longer take fright as the great noisy engine rushes madl}- 
by, and the}^ are best observed, perhaps, from the windows of passing 
trains. Their indifference at such times is amazing. I have often 
watched them from the "Overland Limited,'' some standing erect 
on their mounds; others chasing one another about or quietly feeding 
within 40 or 50 feet of the roaring, rushing train, without showing 
the least outward sign that anything unusual was happening. One 
would think the fur}^ and deafening roar would be too much for their 
nerves, but the}^ appear to regard it with absolute unconcern. It is 
extraordinary how soon animals lose their fear of naturall}^ terrif3nng 
objects when such objects come and go frequently without doing them 
bodily violence. 
In summer, prairie dogs are most active mornings and evenings, 
usuallv remaining in their holes during the hotter part of the day. In 
fall the}^ become veiy fat, and apparentl}^ sleep a good deal: at least, 
the}^ are much less regular and are less frequently seen. In winter, 
in the southern part of their range, the}^ may be seen nearly every day 
unless it is stormy. Thus, in Texas and New Mexico the}^ are said to 
come out in good weather shortl}^ after sunrise, even at times when 
the temperature is below freezing. On the northern plains they hiber- 
nate irregularly, but still appear at intervals. The periods of hiberna- 
tion are probably determined b}^ storms and by the length of time the 
ground is covered with snow, for in Montana and Wyoming they have 
been known to appear, in places where the ground was ))are, on calm 
sunshin}^ days in midwinter when the mercur}^ stood at or below zero. 
Prairie dogs, like the desert species of kangaroo rats, pocket mice, 
ground squirrels, and other rodents of arid regions, are able to live 
and thrive without drinking. In many places the only moisture they 
take into their systems is the small quantity contained in the dry 
grasses, seeds, and roots they eat. In arid western Texas they are 
abundant in places where the annual rainfall is slight and uncertain 
and where some years pass without any rain. With respect to the 
theor}' that their burrows are deep enough to reach water, it need 
onl}^ be said that in some of the dog towns artesian wells have been 
sunk to the depth of 1,000 feet without striking water. 
