From the end of this tunnel the beavers cleared a dragway about eighteen inches wide to the aspen grove. In doing this they cut through three or four large logs and tunnelled under a number of others. Then aspens were felled, cut in short sections, dragged to the end of the tunnel, pushed through this out into the pond beneath the ice, and finally piled on the bottom of the pond close to the house.
Solid snowdrifts formed in the grove while this slow work of transportation was going on. A few aspens were cut from the top of a five-foot snowdrift. The following summer these stumps suggested that prehistoric beavers--large as bears--had reappeared on earth.
At last cold, ice, snow, and enemies completely stopped the beavers"
harvest gathering. The food provided for the colony"s winter supply was less than one half that needed. But the beavers had done their best, and come what may, they would alertly, stoically meet it.
These colonists had a hard winter. I visited them a number of times.
Now and then snow covered the frozen pond, but usually the wind in sweeping down the open-stream avenue through the woods left the ice clear. One day, looking through the clear ice of the pond, I counted six beavers, but on most occasions I was able to see only one or two.
The population of this colony probably numbered twelve or fifteen.
The upper part of the area flooded by their pond had been a semi-swampy tract bearing thick growths of water-loving plants. The roots of sedge, bulbs of lilies, tubers of many plants, and long juicy roots of willow and alder were made use of by these beavers facing a food-shortage.
I supposed it was only a question of time before they would be shut off by the thick ice from this root supply. But they dug a deep waterway--a ca.n.a.l about two feet wide and nearly as deep--from the house in the centre of the pond to the heart of the rooty area. Even after most of the pond was frozen to the bottom they had an open line of communication with the root supplies.
Mutual aid is a factor in beaver life. I do not know how many days"
work this ditch required; but when one of the beavers in a colony work, all work. Since late summer these beavers had worked at one task after another; they had unitedly worked for the welfare of each member of the colony. With mutual aid beaver colonists achieve much in a short time. Their strong love for home, causing them to remain long in one place, and the peculiar work which this calls for, makes changes on earth sometimes enduring for centuries.
But they had only commenced to dig out the roots on the bottom of the pond when the ever-thickening ice froze over this life-saving food supply. The water would have been deeper over this area but the beavers" early hard luck had prevented their building the dam as high as it should have been.
I do not know how they handled the food-shortage, whether or not they went on short rations. But no beaver had more than his portion, for beavers are cooperators, they work in common, and so long as the food supply lasts each has his share.
I had glimpses of the beavers" eager digging through the clear spots in the ice. They tore the root-filled section to pieces and devoured all that it contained. But not until the following summer, when the broken dam released the water, did I realize how deeply and completely the bottom of the pond had been stirred and ploughed. I have seen gardens uprooted by hogs, and mountain meadows dug to pieces by grizzly bears, but neither of them equalled this.
The supply of roots ran out and the bark of the green aspens was eaten off, and still this mountain region was white with winter and the pond locked and sealed with ice. Beavers are strict vegetarians. There were trout in the pond, but these were not caught; nor were the bodies of the starved ones eaten, as sometimes occurs among other animals. The beavers must escape from their now foodless prison or perish.
Spring examinations which I made indicated that they had tried to escape through the long tunnel which had been made to obtain the aspens, but this had nearly filled with ice. They had then driven several feet of a new tunnel, but evidently found they could not accomplish it through the frozen, gravelly earth. Beavers are engineers--the handling of earth in building dams or in the making of ca.n.a.ls is as much in their line as tree felling--but cutting and tunnelling through gravelly, frozen earth is near impossible for them.
They then attempted to cut a hole upward through the two feet of ice, as I found out later when the ice was breaking up. And they had almost succeeded. On the edge of their house they had raised a working foundation of mud and sticks and gnawed upward to within three or four inches of the surface. Beavers are expert gnawers and have been known with their powerful teeth and strong jaws to gnaw off and fell trees more than two feet in diameter. Perhaps they might have succeeded eventually, but they apparently found another and better way out of the pond.
What they finally did was to tunnel out through the unfrozen earth beneath the bottom of the dam. They had commenced on the bottom of the pond and driven a fifteen-inch tunnel nearly level through the base of the dam, and a foot or two beneath the water and below frostline. This came out in the ice-covered stream channel, beneath the frozen earth.
As this tunnel had to be dug under water, it must have been slow work and to have constantly called for relay efforts. When a working beaver had to breathe it was necessary for him to swim to the house and climb up to the floor, above water level, in order to obtain air.
Tracks of six muddy-footed fellows on the snow at the outer end of the successful tunnel told the number who survived the winter"s food-shortage. Spring came, and warmth and flood water broke up the ice on the pond about a month after they escaped. No young beavers were seen. These surviving beavers lived in bank holes along the stream until summer. Then they wandered away. Late that August they, or six other beavers, came to the place. They completed the dam and repaired the house, and by mid-October had a huge pile of food stored in the pond for the winter.
CHAPTER XVI
DOG-TOWN DIGGINGS
About thirty years ago a cowboy took me out to see "The big Dog-town."
This metropolis was in the heart of the great plains near the Kansas-Colorado line. For five hours we rode westward along the southern limits of the town. It extended on over the horizon more than two miles wide and about forty miles long. A town with a population of two million!
Its visible inhabitants would have astounded a census-taker or a dog-catcher. Thousands of prairie dogs were yipping and barking more than sixty times a minute, and stub tails were whizzing away at the same time. We rode out among the crowded and protesting dogs and stopped to watch them. A number ducked into their holes.
Around each hole was an earthy collar less than two feet across and four or five inches high. At a distance this earthy collar surrounding the hole had the appearance of a low mound. Evidently this mound is to keep out storm water.
There were thousands of these holes, each with its dog. One near-by dog sat up on his mound like a ten-pound sea lion. He watched us with concentrated attention. His tongue and tail were still. When my hat started toward him he simply dropped into the hole. There were scattered holes which had a rabbit or two little owls at its doorway.
Throughout the town were little orchards of dwarfed sagebrush and a scattering of tall weeds. A showy bed of p.r.i.c.kly pear cactus inside the town limits was not inhabited.
The prairie dog is a sun worshipper. He keeps aloof from localities where willows are an enemy-hiding screen and where trees cast a shadow. His populous cities are in arid lands where for three hundred days each year they have their place in the sun.
The dogs seemed to be ever moving about, visiting or barking. A young dog near me ambled over to visit another. These two called on a third and while in session were joined by one"s, two"s, and companies until there were several dozen ma.s.sed.
A young dog left his hole-top after a survey and started off for a call. But he turned aside to join and mingle with the crowd for a minute or two, then went on with his call. All this time there were several dogs behind me energetically protesting at or about something. Cheerfulness 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 gra.s.s was the princ.i.p.al food. They also ate of the various weeds around. I do not recall seeing them eat the bark of sagebrush or any part of the p.r.i.c.kly pear.
Prairie dogs must materially a.s.sist 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 movement. 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 the rocky region from the Canadian line to Mexico.
Dog towns are dry towns. My cowboy friend had repeated to me what everyone thus far had told him:
Prairie dogs dig down to water.
Prairie dogs, snakes, and owls all use the same den.
The water supply of dog towns and also their congested life so interested me that I visited a number of them to study the manners and customs of these citizens.
For two months not a drop of rain had fallen in Cactus Center. Not a bath nor a drink had the dogs enjoyed. I hurried into the town immediately after a rain thinking the dogs might be on a spree. I had supposed they would be drinking deeply again and swimming in the pools. But there was no interest. I did not even see one have a drink, although all may have had one. A few dogs were repairing the levee-crater rim of their holes, but beyond this things went on as usual. The rain did not cause dog town to celebrate.
On a visit to the "Biggest dog town in the world," near the Staked Plains in Texas, and where there were dogs numbering many millions, I watched well drillers at a number of places. Several of these wells, in the limits of dog town, struck water at three hundred feet, none less than this depth. This told that dogs did not dig down to water.
They are busy diggers and have five claws on each foot but they do not dig through geological ages to obtain water.
One day two cowboys came along with a shovel which was to be used in setting up a circular corral and I excited their interest in prairie dog dens. We made the dirt lively for two hours but we did not reach bottom. I examined old and new gullies by dog towns but learned nothing. Finally, a steam shovel revealed subterranean secrets.
This steam shovel was digging a deep railroad cut through a dog town.
The dogs barked and protested, but railroads have the right of way.
The holes descended straight and almost vertically into the earth to the depth of from ten to fourteen feet. From the bottom a tunnel extended horizontally for from ten to forty feet. There was a pocket or side pa.s.sage in the vertical hole less than two feet below the top: and a number of pockets or niches along the tunnel with buried excrement in the farther end of the tunnel. The side niches were used for sleeping places and side tracks. There was a network of connecting tubes between the vertical holes and communicating tunnels between the deeper tunnels.
I found the underground works of the dogs similar in other railroad cuts. None of the holes reached water, in fact, they were extra dry in the bottom.
Prairie dogs in common with many species of plants and animals of the arid districts require and use but little water. Dogs do without water for weeks except such moisture as is obtained from plants eaten. A part of each year the plants are about as dry as dog biscuit.
There were from a few dozen to a thousand dogs upon or in an acre; from a few holes to more than one hundred in an area the size of a baseball diamond.
Although the plains had numerous large and populous places there were leagues without a single dog. Apparently the dogs keep on the higher and the well-drained land.
One day I watched some fat, happy puppies amusing themselves. They played, but without much pep, while mothers remained near to guard and to admire.
Prairie dogs often play. But never, I think, alone like the grizzly.
In groups and in hundreds they played the universal game of tag. They were fat and low-geared and their running gallop made an amusing effort to get somewhere. There were several boxing exhibitions, or farces. Their fat bodies and extremely short legs and slow, awkward movement made their efforts more ludicrous even than those of fat men boxers. There was a kind of snake dance with entangled countermarching in which most dogs tried to be dignified while many acted as though in new company and did not know what was expected of them.
One of their plays consisted in a single dog mimicking a stranger or an enemy. A bunch of dogs acted as spectators while an old dog highly entertained them by impersonating a coyote, at least his exhibition reminded me very much of coyote. The old dog imitated the coyote"s progress through dog town, with the usual turning, looking, smelling, and stopping. He looked into holes, rolled over, bayed at the heavens, and even tried the three-legged gallop. During most of his stunts the spectators were silent but toward the last he was applauded with violent cursings and denunciation--at least so it sounded. A number of other folks were imitated, but just who they were my natural history and the actor"s presentation gave no clue. Apparently the skunk was imitated. The actor"s interpretation was good. The congested audience watched him closely, with now and then a yip, but mostly in silence.