REBUILDING A BEAVER COLONY
In passing the Meadow Beaver Colony one July afternoon I saw an old
beaver come up out of the water with a ball of mud in his forepaws. He
jammed this mud into a low spot in the dam. Tracks in the mud along
the top of this old dam, and a number of green aspen sticks with the
bark eaten off lying on the side of the house, showed that a number of
beavers had been using this old house and pond for several days.
This was interesting because the place had been abandoned fifteen
years before and most of the old beaver works were in ruins. One
house, now a mound overgrown with willows, retained its form. The pond
it was in had not filled with sediment.
Did this repairing of the dam mean that this old colony was to be
resettled by beavers? It probably did, for the beavers ever work for a
purpose and not just to be working. It was mid-summer and all beavers
who were not making emergency repairs or extensive improvements were
off on a summer vacation.
Beavers, like people, occasionally settle in scenes formerly occupied
by their kind, and build among the ruins of the long ago. Many a
beaver colony, like many an ancient city, has one or more cities
buried beneath it.
A few days after seeing the big old beaver at work on the dam I
discovered him digging in a canal all alone. Tracks showed that other
beavers had been working in the canal, but just why this one was so
bold and showed himself during the daytime I could not guess.
That these beavers were at work on a canal left no doubt about their
having come to stay. Meantime, the beavers occupied the old house and
pond while making this canal and doing other pioneer settlement work.
They cleaned it out and patched it up for a temporary camp only.
A canal is one of the best exhibitions of beaver skill. About twenty
feet of this canal was finished and it was about three feet wide and
eighteen inches deep. It began in the northeast corner of the old pond
and was being dug across a filled-in grass-grown pond which had been
washed full of mud and sand. It pointed at an aspen grove out in the
pines two hundred feet away. It was probable that this canal would be
dug as close as possible to the aspen grove, then the canal filled
with water from somewhere and used to float aspen poles down to the
beginning--the lower end--of the canal. And close to the lower end a
house was almost certain to be built.
[Illustration: Meadow Beaver Colony
Water level in canal 3 feet higher than level in pond
Canal 15 inches deep 30 inches wide, 70 feet long
Aspen grove 120 feet from house.
Willows grass aspen grove where food is obtained
Canal dug in meadow formed by silt and sediment filling
old beaver pond
A Beaver Canal]
A buried log in the canal was gnawed in two and removed. The canal
curved around a boulder too large to be removed. At a distance of
eighty-one feet from the lower end the canal-builders came in contact
with granite rock and brought the canal to a stop by enlarging the
upper end into a basin about ten feet across.
The entire length of this canal was through the sediment of a former
beaver pond. After making a pond beavers must occasionally raise the
height of the dam to deepen the water, and also dredge the mud from
the bottom. But despite both dredging and dam raising, the pond sooner
or later fills with sediment and has to be abandoned. In due time it
is overgrown with grass or a forest.
Food shortage--complete exhaustion of the aspen growth--had compelled
the abandonment of the Meadow Colony after it had been a beaver
settlement for a great many generations. Two large ponds, a dozen
smaller ones, and three houses were left to their fate. Most of the
smaller ponds were completely lost, being overgrown with willows. Two
of the houses had crumbled and were now low wild flower beds.
Since abandonment a number of aspen groves had grown, and although
these were some distance from the stream, they could be reached and
would furnish necessary food supply.
These settlers had come from about ten miles down stream. During
summer vacations beavers make long rambling journeys. It may be that
some of these beavers had visited this old colony and knew of its
opportunities before coming to settle.
From time to time during evenings I had glimpses of several of the
beaver settlers. From their appearance and from their footprints they
were mostly young beavers. During the autumn I several times dimly saw
them playing in the twilight. They splashed merrily about in the pond,
the entire colony taking part.
With mud and willows the beavers repaired the breaks in the
but-little-damaged dam of the old pond. Then they cut a ditch thirty
or forty feet long through a ridge to a little pond to the north, and
filled the old large pond. Its waters extended to within twelve or
fifteen feet of the lower end of the canal. But as the canal was
nearly two feet higher than the surface of this pond, water for the
canal would have to come from a higher source, and I was puzzled as to
where this might be. But beavers plan their work two or three moves
ahead, and they probably knew what they were about.
Commonly a house is built in the pond or on the edge of it. But on a
little space of raised ground, within ten feet of the lower end of
the canal and the edge of the pond, the foundation for a house was
being excavated. Two tunnels were made through it to the bottom of the
pond.
The house was made of mud dredged from the bottom of the pond, and
this was reënforced with an entire clump of willows cut near by. There
were also used willow roots, sods, a few stones, and a few peeled
aspen sticks off which the beavers had eaten the bark, and which they
dragged from their temporary home--the old house.
The finished house was about ten feet across the bottom and five feet
high. The walls were about two feet thick. The ventilation top was a
mass of criss-crossed sticks without mud.
Beavers do most of their work at night--this probably is for safety
from men. It appears that at one time they may have regularly worked
during the daytime. But for generations hunters with guns have made
day work perilous. In out-of-the-way places where they had not been
disturbed I have seen a whole colony at work during the daytime even
when the work was not pressing. With exceptions they now work daytime
only in emergencies. At this place no one was troubling the beavers
and frequently I saw an old one, and at length I realized that it had
been the same old one each time.
I was sitting on the side of the beaver house one afternoon changing
a roll of films when the old beaver rose on the pond and swam to a
half-submerged log about twenty feet away. I stopped film changing and
sat still to watch him. He had not scented me. Splendid reflections he
and the surroundings made in the water; the snowy top of Mount Meeker,
the blue sky, white clouds, brown willows, green, pointed pines, red
birches, and a single young aspen with yellow leaves--a brilliant
autochrome of autumn.
The beaver rose from squatting and scratched himself behind a fore
leg, combed himself with forepaws, then standing high on his hind feet
held forepaws close to his breast and looked around. A fly alighted on
his nose. He struck at it. Again it alighted, and he brushed it away
with the other forepaw. Again he squatted on the log but facing in the
opposite direction. A few minutes later he dived off showing his wide,
webbed, gooselike hind feet, and striking the water a heavy, merry
whack with his broad black rubbery tail, sending the ripples scurrying
over the pond.
The canal still remained empty, but with the completion of the house
it would be filled from somewhere and used in bringing in the harvest.
One day late in September I found the canal and the little basin at
the south--the upper--end full of water. A spring concealed among
the willows forty feet above had been used. From the spring a small
ditch had been dug by the beavers and through this the water was
pouring rapidly into the now overflowing canal.
[Illustration:
_Photo. by S. N. Leek_
_Mountain Lion_]
[Illustration:
© _by C. L. Reed, Jr._
_Bighorn Mountain Sheep_]
Early one evening, two days later, I peeped through the willows near
the south end of the canal and saw an aspen pole with two or three
twigs and several leaves fluttering from it. It was moving down the
canal toward the house. The old beaver was propelling this. Both
forepaws were against the end of the pole and he pushed it speeding
toward the house at the lower end of the canal. He left this pole in
the water and returned for another, then another.
When he arrived with the third there were two beavers dragging the
other poles over the short wet space between the end of the canal and
the edge of the pond.
These aspens were being canned in the water--stored in the pond--from
which during the winter they would be dragged in short sections up
into the house and their bark eaten.
A green aspen commonly water-logs and sinks inside of thirty-six
hours. The beavers were simply piling one pole on another, evidently
realizing that the sinking would follow.
The following afternoon I saw the old beaver in the aspen grove
gnawing away at a seven-inch aspen. This was nearly cut off. In giving
the finishing bites he tiptoed, edged around the stump this way, then
that. When it began to crack and settle he started toward the canal.
He caught a small piece of aspen in his teeth, dragged this down into
the canal and left it, and swam on down to the house.
In the water-filled basin at the end of the canal apparently the fresh
cuttings were collected and later transferred by water to their place
of deposit in the pond. These aspen chunks were from five to eight
feet long, were parts of small aspen tree trunks freshly cut off at
each end.
Down in the pond, floating above the deposited pile, were numbers of
aspen limbs and tops. The bark of these as well as of the larger
cuttings was to serve as winter food for the beavers.
Beavers do not eat meat or fish, but chiefly bark, with a little of
roots, mushrooms, lily bulbs, and berries. Yet several times during
the past year I read of beaver catching fish--out of season, too.
This old beaver frequently appeared, first at one place and then at
another. Each time, too, in daylight. He did not seem afraid. But the
other beavers were not seen except about sundown, or in the twilight.
This old beaver may have been the leading colonist, the ruler of the
colony, if there be such a position.
Beavers coöperate and carry out a distinct plan; in doing this they
work both unitedly and singly. The whole work, however, advances as
though to a plan and as though under constant supervision. Through the
years I have seen beavers working hundreds of times. Their work is
nearly always efficient and apparently under the direction of an
expert in beaver work; but never have I seen any sign or signal given
by a beaver that I could positively say was an order or command. But I
see no way of explaining the magnitude of beaver works and the skill
shown therein except through coöperation under an acknowledged leader.
One evening as I was watching, a bobcat chased two beavers into the
pond. A few yards farther and they would have been overtaken. But the
instant they dived into the pond they were safe.
The wild enemies of beavers are lions, bears, wolves, and wildcats; in
fact, any flesh-eating animal large enough to kill one. Rarely is a
beaver captured in water; he is a swift swimmer and can long remain
under water. But on land he is slow getting into action, is not agile,
and in going has only low gear. For safety he aims to cut trees that
are closest to the water.
Another evening four, and a part of the time five, beavers were
pushing and dragging a log. When they at last pushed it into the canal
one beaver with only one forepaw put this forepaw against the end of
the log and conducted it down the canal. For safety for travel, and
for transportation beavers need deep water.
There is a social side, too, to life in these deep-water homes. Not
only do beavers indulge in all kinds of water sports among themselves,
but they seem to make friends with some of their diving, swimming
neighbours in other animal families.
I had often heard that beavers ever war upon their little brother, the
muskrat. The beavers in this colony did not. They continued to use the
old repaired house until near the close of their harvesting. On their
departure, apparently muskrats at once took possession. But the
beavers often went back into the old house.
One day I saw a beaver enter the house. There were a number of
muskrats inside. I do not know the nature of his visit but there was
no excitement. Another time a beaver turned aside and touched noses
with a muskrat. Still another time a beaver playfully dived beneath a
muskrat. As the beaver came up the muskrat grabbed beaver fur with
forepaws and sat down on the beaver’s back. Away swam the beaver with
back above the water, little brother holding on.
The harvest of aspens for winter food was nearly finished, and I had
thus far seen only the old beaver doing any tree cutting. The evening
of the 19th of October I had gone through the aspen groves measuring
and counting. One hundred and twelve aspens had been cut; these were
from two to eleven inches in diameter at the place of cutting, and
from five to nineteen inches above the ground. The aspens were from
twelve to twenty-one feet high.
Just at sundown, as I sat down on a boulder near the aspens, I saw a
beaver swimming in the canal toward me. In the basin at the end he
smelled of two logs, then came waddling heavily up the much-used trail
over which logs were dragged from the aspen grove. His big tail swung
slowly from side to side, in places dragging on the ground. He was an
old beaver that I had not before seen. He must have weighed fifty
pounds. He glanced right and left at aspens and stopped several feet
from one, rose up, looked into its top, turned, and looked into the
top of another. He went to the second one. Later I saw that the first
one was entangled at the top in the limbs of a near-by pine.
Squatting on hind legs with tail bracing behind, he reared up and put
forepaws against a four-inch aspen. He took several bites into the
tree; then several inches higher--as high as he could reach--he did
more biting; after this he split and bit out the space between these
two cuttings. He then repeated cutting above and below and again
followed by splitting out the chip between--roughly following the plan
of an axeman.
Once he stopped to scratch; he rubbed his back against the stump, and
clawed at the itchy spot with left forepaw. He ate a mouthful of bark
and resumed work. All the cutting had been done from one side, and for
the few final bites he scraped a quantity of trash against the stump
and stood upon this so as to reach the last bit to be cut off. He was
two or three minutes less than an hour in cutting off this four-inch
aspen, but aspen is of soft wood. He galloped behind a pine until the
aspen tumbled over. Waddling back to it, he snipped off several little
limbs, a single bite for each. He scratched his neck. Then he fell
rapidly to gnawing the trunk in two. But before this was accomplished
he took fright, perhaps from my scent, and went full gallop like a fat
cow to the end of the canal and dived in with tail whack and splash.
During summer beavers eat their meals on the side of the house, or
bank of the pond, or on a log or boulder that is above the surface of
the pond. If enemy appear the beaver in a second dives to safety. For
the winter meal the beaver goes through the inclined tunnel from the
house into the water. At the food pile he cuts off a short section of
one of the aspens, takes this up into the house, and sits on the
floor, which is above water level, to eat the bark.
Two hundred and eight aspens were cut in the grove, dragged to the
canal, floated down this and finally deposited in the pond. This made
a large food supply for the winter. A little more than one half these
were used, and the number of colonists fed probably was nine.
Each spring beavers come out of winter quarters as early as possible
and at once begin to use fresh food. If any of the winter food harvest
remains canned in the water this is thrown out next autumn and used in
dam and house repairs.
Many old beaver colonies have a den in addition to the house, and
others have a tunnel under the pond that comes out on shore some
distance beyond the shoreline. This tunnel is sometimes used in winter
while the pond is frozen over. But these new settlers were without
tunnel or den.
These beaver pioneers had founded a new home before winter came. The
house was completed, a deep water pond had stored in it the autumn
harvest--food for months. This necessary work was completed a month
before the pond froze solid and several weeks before the first snow.
This main pond is off the stream, connecting with it by a ditch
through the side of another pond, and will thus receive but little
sediment. But each year a layer of fine material will sift in and
settle on the bottom, making the pond shallower. Although this pond
will live longer than most ponds it, too, will meet the common
fate--be filled in with rich soil, be buried and forgotten beneath
grass, wild flowers, willows, and groves of trees.
Several times through the ice I saw the beavers in the pond. A number
of times I watched them by the food pile cutting off sticks of
rations. Other times they were swimming about as though just having
their daily cold bath.
While the glassy ice covering of the pond was still clear I once saw
them at play in the water beneath the ice; all nine. They wrestled in
pairs, they mixed in masses, they raced two and three, they followed
the leader circling and criss-crossing. Now and then one dropped out,
rose against the under surface of the ice where there was an air
pocket, and here I suppose had a few breaths and then resumed the
play.