The Adventures of a Grain of Dust Part 16

[Ill.u.s.tration: COUSIN ECHIDNA

The echidna--you can see one in the New York Zoo--is closely related to our duck-billed friend and is also a native of Australia. It uses that long, tapering nose and those claws to burrow for the ants on which it lives.]

Still the scientists didn't know what to call this paradox of the animal kingdom; so they named him just that--paradoxicus, _Ornythoryncus paradoxicus_. A little Greek boy, without having to look it up in a dictionary, would have told us that "ornythoryncus" means "bird-billed"; for it's like those Greek picture words that always told their own story to the little Greeks. As for "paradox" if you don't know what that means, look it up in the dictionary and then look at the _Ornythoryncus paradoxicus_, and you'll understand.

IV. THE BEAVERS

Of course you wouldn't like to be a duck-billed mole--n.o.body would, but I always thought it would be rather nice to be a beaver. The beaver is, in many ways, the most remarkable of all the water people that help make the lands that give us bread.

[Ill.u.s.tration: BEAVERS AT WORK AND AT PLAY

Whether he's working because he is more industrious than those beavers in the water or because it's recess time with them, the young beaver gnawing the tree seems to be having quite as good a time practising his profession as the others do in playing about.]

But it is not alone for the amount of work he does that I admire Mr.

Beaver so much; it is for his intelligent, not to say brilliant, way of doing it. Suppose, for instance, you had to build a house out in the water, the way our great, great-grandparents, the lake-dwellers, did, to protect yourself from enemies and for other reasons. And then suppose you didn't have any _tools_; nothing but a pair of paws and a set of teeth. Could you do it?

Another thing: The lake-dwellers had plenty of water to build in; plenty, but not too much. The beavers don't have this advantage. They usually build in the water of flowing streams, and they have to make their _own_ lakes. How would you do it; even if you had tools? But remember, being a beaver, you've got nothing to use but two honest paws and a set of teeth. It was with these Mr. Beaver did it all--with his teeth, his paws, and his head; the inside of his head, I mean--his brain. Take the matter of water arrangements. He gets the water to lie quietly and at just the right depth by building his dam across the stream. This dam not only provides him with water of just the right depth to protect his front door from enemies and to keep rus.h.i.+ng torrents from carrying his house away, but the spreading out of the original stream bed into a pond helps in gathering the Fall harvest of trees, since it brings the trees nearer to the water's edge, and water transportation among beavers, as among men, is always cheapest.

Although dams are usually built of trees which the beavers cut down themselves, they also use cobblestones where trees are scarce; for Mr.

Beaver is a very thrifty soul; he doesn't waste material nor time nor effort. Many books about beavers say they cut the trees so they will fall across the stream, but Mills says, in his book on the beaver, written after many years of patient observation, that beavers don't seem to care how the tree falls, just so it doesn't fall on _them_! Not but what they _could_ cut trees to fall in the water if they thought best; for just watch them build a dam and see how clever they are; cleverer, possibly, than some of us.

[Ill.u.s.tration: BEAVERS AT WORK ON A DAM

See how many of the features of the building of a beaver dam, as described in our story of these wise little people, you can make out in this picture.]

Let's see. Say you've got your trees up to where the dam is to be; now how are you going to set them in building the dam?

SEE IF YOU'RE AS CLEVER AS MR. BEAVER

"Right across the dam," you would say, wouldn't you? That is what most people have said when I have asked them that question; for that is the way men do it. But remember, if you built the dam as men build dams you would have to drive stakes or do something to keep the logs from was.h.i.+ng away. Years ago, when writers used to theorize a great deal on how things were done, instead of getting outdoors and watching patiently to see how they actually _were_ done, it was said that Mr. Beaver in building his dam did really drive stakes and that he did it with that big tail of his. But what Mr. Mills found was that the beaver lays his trees lengthwise of the stream. You see why that is, don't you? When the trees are laid lengthwise, the water, instead of striking them broadside, strikes only the end and so there is less likelihood of their being carried away.

Another thing, two things, about the trees in the dam--in fact four:

1. It wouldn't do, you see, to lay the trees broadside to the stream, but what position could we give them that would help still further in keeping the water from carrying them away?

2. Shall we use trees with the branches still on them or trees trimmed down like sticks of cord-wood? (What kind do you see in the picture of the beaver dam?)

3. Or shall we use both trimmed and untrimmed trees? If so, why? And how?

4. If we use untrimmed trees, which end shall we put up-stream? The b.u.t.t or the tip?

[Ill.u.s.tration: SECTION OF A BEAVER DAM

You can see that there was a sufficient flow of water in the stream from which this sketch of a section of a beaver dam was taken; otherwise the dam would have been plastered with mud to conserve the supply. The longest slope, of course, was up-stream--a fundamental principle in beaver bridge engineering.]

In building his dam the beaver uses, for the most part, slender green poles trimmed and cut in lengths; but mixed with these are small untrimmed trees which he places with the b.u.t.t end up-stream, and propped with mud and sticks so that the up end will be a foot or so higher than the down end. In this way, you see, the branches are made to resist the push of the waters against the b.u.t.t end; while, if they were placed the other way, the current would have a pulling purchase on the b.u.t.t end.

The raising of the ends also lessens the pus.h.i.+ng force of the water as it doesn't strike the b.u.t.t of the tree "full on," as it would otherwise do. And the branches not only help to hold the trees in place, but, together, form a kind of foundation on which to pile and intermix the trimmed poles.

The timbers, being cut green, become water-soaked. This makes them heavier and so causes them to sink and helps to hold them in place; while the branches and twigs of the untrimmed trees form a kind of basketwork that catches the sediment and drift of the stream, and so the dam lets less and less water through. The upside stream is plastered by the beavers with mud in cases where the flow of water in the stream is meagre. Otherwise it is left unplastered. You see Mr. Beaver's idea is not to make the dam absolutely water-tight, for then it would be running over all the time and so be worn away. What he wants is a dam that will let the water through slowly and at the same time keep a proper level.

[Ill.u.s.tration: BEAVER HOME WITHOUT TIME LOCK

Here is a beaver home as it looks before the time lock is put on in the Fall.]

Mr. Beaver's chief purpose in building these dams seems to be to keep his front-door yard full of water. This may look like a funny idea at first, but in this, as in other things, Mr. Beaver shows he has a very wise head on his shoulders; for one peculiarity of his life is that he is obliged to come and go through the cellar door. As he doesn't want any of his enemies--the wolf, the coyote, and all that cla.s.s of people--to use this door, he keeps it under water. And in winter-time, when he goes out to the wood-pile to get something to eat, the water must be deep enough so that the pond doesn't freeze solid to the bottom.

[Ill.u.s.tration: A BEAVER HOME WITH TIME LOCK

Here, as it looks after being made secure against hungry wolves and the Winter winds.]

As for those professional highwaymen, the wolves and coyotes, that are so much bigger than he is, Mr. Beaver keeps out of their way in Summer, when they don't bother much about him, anyway, as he sticks so close to the water and is hard to catch. In the Winter, when they get hungry and desperate and would break into his house, if they could, he makes it practically burglar-proof, by putting on a time lock; a lock that just won't open, even to a wolf's sharp claws, until Spring.

And in the simplest way.

Just before Winter sets in Mr. Beaver plasters the outside of his house with mud, and the mud freezes as hard as a stone. But sometimes, even among the beavers, there are s.h.i.+ftless characters, like that Arkansas man who just _wouldn't_ look after his roof. These careless beavers don't plaster their roofs. But then, just see what happens! Some hungry wolf comes along and breaks through and has a nice fat beaver for supper, maybe. And maybe not; for, even in that case, if Mr. Beaver wakes up in time, he dives down through the cellar door and into the tunnel and out under the ice.

"Aha! You got fooled that time, didn't you? You mean old thing!" (Can't you almost hear him say it?)

In putting the mud coating on their houses or dams the beavers carry it in their fore paws. Sometimes, in a very steep place, they climb up the roof with three feet and hold the mud with one. When they have delivered the mud they use these same little paws to pat it down--not their trowel-like tails, as one would naturally suppose.

THAT MYSTERY ABOUT THE BEAVER'S TAIL

Then what _do_ they do with those tails? Well, for one thing, they sometimes use them to carry mud by curling them between their legs and holding the mud against their bodies. Perhaps they resort to this way of carrying mud where they have such a steep climb up the roof they need all four legs to climb with; or it may be just an individual fancy of some beavers. For, being really _thinkers_ and not mere machines, acting entirely on what is called instinct, different beavers have different ways of doing things. The beaver's tail is also very useful in swimming, and Mr. Beaver is a great swimmer. You should see him. He swims mostly with his hind feet and tail, holding his fore paws against his breast as a squirrel does when he's sitting up looking at you. His tail he uses as one uses an oar in sculling, turning it slightly on edge as he works it back and forth.

But he has two other important uses for this big tail, as we shall now see; for the beavers of this colony we are watching, having put up their dam and built their big house, are now ready for the Fall harvest that is to provide for the long Winter. The beavers are strict vegetarians.

Their diet consists of the tender bark of young trees and roots dug from the bottom and along the banks of the ponds in which they live.

"But, for mercy's sake, where are they going to get the tender bark of trees in the dead of Winter, when all the trees are frozen solid and the beavers can't get from under the ice anyhow?"

Well, Mr. Beaver has thought out just how to do it and we didn't. That's the beauty of being a beaver. What he does is to cut down small trees, trim them, divide them into lengths, and then heap them up in a great pile at his door, under the water.

By the time they are three years old beavers feel grown-up; as, indeed, they are in size, although, like certain other young people I could name, they have a great deal yet to learn. At this age they choose their mates and either settle down in the home colony or go away somewhere else.

School takes up with the beavers in September. All through September and October the harvest is gathered and preparations made for the long Winter. The baby beavers of the Spring, who by this time are four or five months old, take part in the harvesting; at least they play at it.

They don't do much, but they learn a great deal. Now let's all be little beavers for a few minutes and see what we can learn. We are out in the harvest-field--the woods--with father, and he's going to cut down a tree for the Winter food-pile. Watch him.

He picks out a young tree something less than six inches thick. Then he looks up as if he wanted to see what kind of a day it was going to be; although the fact is he never bothers his head about the weather. What he is really looking up for is to see if the top of the tree he is going to chop down is likely to get tangled in the tops of other trees when it falls. (All beavers, I should add, don't take this precaution; only the older and wiser ones.) After this inspection he either cuts the tree in two with his long sharp chisel teeth so that it will fall clear of the tangling branches of other trees, or, if he sees he can't prevent this, he moves away to another tree.

Just before the tree is ready to fall he thumps the ground several times with his tail to warn other beavers working near by. They all scamper as fast as their fat bodies and short legs will let them. If they are near water, as they usually are--they "plunk" into it. After the tree falls the limbs are cut off, the trunk gnawed into sections four to six feet long, depending on the size of the trunk, the distance from the water, and the number of beavers that are going to help move it.

Although, as a rule, only one beaver works on a tree in cutting it down, they all pitch in and help in getting the sections home; dragging them across the ground and into the pond or into one of their wonderful ca.n.a.ls.

THE BEAVERS AND THEIR PANAMA Ca.n.a.lS

The beavers knew all about digging ca.n.a.ls long before the days of Colonel Goethals. They dug them for much the same reason we dug the great Panama Ca.n.a.l, to save time and expense in moving freight and for protection from possible enemies. On land the beaver is easy prey for wolves and such, but once in the water he can laugh at them. These ca.n.a.ls not only enable him to haul his wood easily and safely, but are just the things to dive into when somebody is after you. Another purpose of the ca.n.a.ls is to fill ponds where water is getting low; or to make a pond where there isn't any at all, as in a dry ravine.