THE WONDERFUL BEAVER

Taranaki Daily News, Volume LI, Issue 223, 14 September 1908, Page 4

THE WONDERFUL BEAVER

Of all animals, . beavers show the greatest constructive ability. Wltere they are not molested, they bV.ald a. dttui across the valley of some sn ailstream, and thus make an artiflmf! pond, in which tiiey build one or more houses of sticks and mud.

11l this article the writer wi.-iies to give an exact acfou;it uf the structure of a beaver ilam which Ik studied very recently, and lie would like to have his readers decide for tiientselv*..'s whether animals call do work ol iliis kind by mere instinct, or whether Un-v work with a higher kind of intelligence. The dam in question is located in ,the mixed forest of Northern Wisconsin. It is ahout 200 feet long, and runs completely across the valley of a swift trout stream. As tiie stream averages, about four feet ia width and ten inches ia depth, the amount of water which must bv controlled is very considerable. 1 should say it is large enough to run a fanner's grist mill day and night for three huudred and sixty-five days in the year. The dam curves ia and out from on? convenient foundation to the other. For a length of 30 feet across the stream and at the lowest part of tile ground it is about five feet high, .nid the water rises within a few inches of the top. In this part It is built of dead brush and sticks which slant down stream. They are all placed liutt down, and make the stream side of the dam look like a palisade of slanting sticks. On the pond side these sticks are fillled in with mud in »ucli a way that tlte dam slopes gently into the' pond, and that the sticks are not visible in the pond itself. The base of the dam is watertight, but the thin top allows ■numerous small streams of water to flow through; but the large amount of wood in the dam prevents the water from cutting and forming dangerous breaks in the dam.

Xear the outer edges, where the water exerts little pressure and linsl 110 current, the dam is only a few inelles high and wide, and is built entirely of mud, which was scooped up in front of the dam. While the central part of the dam looks as if a man might have built it with considerable expense of hard work, the edges look like the tiny mud dams wnich i>;i r.'-footed country children are so fond of making after a hard sliower. After the beavers had built the main part of the dam, they discovered that two separate depressions on trie south side would partially drain their pond. In order to prevent this they built a small dam of mud across each of the depressions. The site of the dam is apparently well chosen. The pond now covers about about four acres, with an abundant growth of small poplars in and near tile pond. The beavers live on the bark and twigs of these trees and have cut down a goodly number. The greatest depth of the water is about six feet, and does not cause a pressure which is hard to control.

The little four-footed engineers seem to have first constructed a trial dam a hundred feet further down the stream.* They abandoned this sit.\ as far as 1 could judge, because it was right in an alder thicket, where it was difficult to work, where but little ready-made building material was at hand, and where their pond would not leave enclosed or approached their favourite fuod trees, th-e poplars. The permanent dam was located on the edge of a natural clearing, where the conditions for work, ready buildingmaterial and food supply were most favourable.

Had tli«y gone about half a mile further down stream they would have had to build a much longer dam. Had they gone a mile'below the present site, where the little valley is much narrower. .th? l dam would have produced a rapidly rising and therefore dangerous head of water. Had the builders gone further up stream their pond would have enclosed a tamarack swamp, but would not have brouyV them near any poplars or otm-7 food trees. In the pond i- one large lodge, housing probably six or more beaver-. I did not see the animals. The po:i I iwithin three miles of a railroad -'a tion, and the animals are very shy and work only at night. The largest poplars which the beavers have cut measure •"» ineTie- in diameter. Tt has been claimed that Ihe beavers cause the trees to fall hi a certain direction, but 1- saw no indication of this. They seemed to iiiv;chiseled around the trunk urnil the tree fell. The animals must have expended a very large amount of energy i';i building the dam. T estimated th.it it would take a strong man at least six days to duplicate their structure, if "he' were not allowed to use sr.i axe for cutting brush, but were allowed to uh> a spado to scoop up M;e needed mud.

X(i\v. tlx- (iH.vtiun is: Tlitf llil'-v hcsivit- work witli anythn;,' akin tn linniaii »r <!'<! Un'V '"irk miller tin' "iiirfii-.ur »f nolliiii" !miL a Miu.l instinct?