A BEAVER LAKE IN SUSSEX.
IN an article in the Cornhi11 Magazine of January, sug- gesting means by which some of the Crown forests might be retained as sanctuaries for wild animals, both native and foreign, a short reference was made to the success of Sir Edmund Loder in acclimatising foreign species at Leonardslee in Sussex. This park is one of the most beautiful in the South of England, situated on high ground on the margin of the Weald of Sussex, near to St. Leonards Forest, with a view over great stretches of broken country bounded by the flats of the Rather and Arun and the distant range of the South Downs. The park itself is divided by a deep, wooded valley, in which a stream forms a series of pools, increasing in size to small lakes, and in one of the connecting lengths of the brook is a beaver colony, in which the method and practice of beaver engineering are shown in as high perfection as in any North American stream. Though they have only been established there for some seven years, they have entirely changed the character and appearance of the ground which they occupy, in accordance with the established order of beaver life. All their work has been open to observation, and, in the process by which the Leonardslee beavers have created the conditions necessary to their existence, the gradual evolution of those perfect beaver villages which struck the first settlers in North America with such natural astonishment has been traced step by step.
Their first object was to form in the running stream a pool, with water maintained at a constant height, sufficiently deep to keep the entrance to their burrow in the bank submerged during the droughts of summer, and to obviate any danger of a thickness of ice so great as to prevent their swimming freely beneath it in winter. To this end the beavers built a dam, which those who have visited their surviving homes in Canada pronounce to be as good a specimen of their work as can be seen even there. Its situation was carefully chosen. A small oak, growing on what appears to have been a projection of the bank or an island in the brook, gives indirect support to the centre of the work. It may be concluded that this was part of their intention ; for though they have cut down every other tree in their inclosure to which they had access, except two or three very large ones, they have left this small tree untouched. Above this stretches the dam, now some twelve yards wide, and rising about Si ft. from the base to the crest. It is solidly built of battens of alder, willow, larch, and other straight-limbed trees, cut into lengths of from 2 ft. to 4 ft. The bark of each was carefully gnawed off for food, and the whole work, con- structed of these cut and peeled logs, has a very regular and " artificial" appearance. Smaller twigs and sticks are jammed in between the battens, and the interstices are stuffed and plastered with mud, which the beavers bring up from the bottom of the pool in their months, and push in with feet and noses, making the whole structure as watertight as a wall. The dam has converted the stream above into a long pool, overflowing the original banks, and 5 ft. deep at the lower end. Here, then, was the beaver- lake, the vestibule to the beaver home. The early settlers and trappers, and the writers who copied and illustrated their accounts, wrongly credited the beavers with as much art in the building of their " lodges " as they justly attributed to them for the construction of their dams. They were usually represented as domed houses surrounded by water, and one illustrator depicted the lodges as pierced with a neat row of
windows. Later naturalists declared that the beaver only barrows in the bank like a water-rat, and makes a chamber at the end. But there was evidence to show that the lodges could scarcely be a myth, and the common consent by which they were described as surrounded by water was rather diffi- cult to explain away. It was surmised that the beavers began by making a burrow, and in time converted this into a lodge. The annals of Sir Edmund Loder's colony afford the first reliable evidence that this surmise is correct, and will in all probability show how the riparian residence in time becomes lacustrine. The beavers dug a burrow, into which they constantly carry fresh dry chips to make a bed. Unlike, the prairie-dogs, they do not throw their old bed away, but simply cover it with fresh chips. As the chamber floor rises they scratch away the ceiling to gain more room until they make a hole in the roof. Over this they lay sticks and cover them with mud. At first only a few sticks showed the top of the lodge. But to make head room they have gradually enlarged the roof till it has risen into a distinct dome some 2 ft. high, and the process mast continue so long as the layer of chips rises below.
The surrounding of this lodge with water may take place in the following manner. Every year the beavers add to the height of their dam. This is not, or is only in part, the result of beaver conscience, which keeps them uneasy unless they have some work to do. The stream in winter brings down a quantity of mud into the pool, which tends to grow shallower. Therefore to keep up the depth of water the dam must be raised in the spring. This again raises the height of the water-line, and floods the banks laterally. Already the fence round their lake has had to be moved back and enlarged on this account. Consequently in time the ground in which the burrow and lodge are made may be flooded, and the lodge will again be raised, and be completely surrounded by water. The growth and expansion of such engineering works as these dams, made necessary by silting, and the inevitable annual raising and widening of the dam, is naturally provided for by the increase of the beaver colony. The young beavers are early set to work at "light jobs." When wild, beavers also work up stream, and make other subsidiary dams to lessen the rush of floods. At Leonardslee the beavers have young ones, though the whole number at present in the colonr is only five, but they are prevented from wandering up the- valley by a low corrugated-iron fence round the inclosure, with gratings across the stream. The fence, though not beautiful, serves a useful purpose. It is a complete screen to the beavers when at work, and to any one observing them from without. Occasionally one burrows underneath it, and travels up the stream, moving on from one pool to another. On the banks are still visible the amusing records of a beaver's "night out." It bad hardly travelled fifty yards before its conscience suggested that it ought to get to work. It selected a very big tree, a Scotch fir about 18 in. through, cut a broad belt of bark off half-way round, and then gave up. It then went up the valley until it found a nice young birch-tree, 6 in. thick. This suited very well. It cat it down, and next morning it was found lying across the path. The stump and chips still remain. Every one who has kept wild animals, even without establishing them in natural conditions, knows how much attention to detail is needed for success. As a minor instance of the cleverness which presides over the doings of the Leonardslee animals, we may cite the means by which wandering beavers are caught. A box trap, open but not set, is kept in their inclosure. In it a piece of dog-biscuit is put daily, which the beavers scramble for. When one gets out, the trap is set by the stream, and the beaver, who misses his morning biscuit, soon smells it, walks into the trap, and is In conclusion, we may point to evidence on the spot of the engineering skill of the beavers, and their grasp of "prin- ciples." Higher up their owner has formed many small pools, stocked with trout and separated by short lengths of running water, cascades, and rushy ground. Some of these pools are no larger than that made by the beavers, yet the dams were constantly broken by floods. The stone outfalla were carried away, the heavy blocks carried into the next pool, and the earthen dams cut by the water. This is now prevented by ingenious wooden 'anthills, with parallel cuts for flood over- flow. The beaver dam, made of "wattle and dab," and care- fully kept level along the top, allows the floods to run over it
without damage. The whole scene and its setting is a complete and beautiful object-lesson in one of the most attractive pages of natural history. Yet it is only one among many of the interesting and successful instances of acclimatisation to be seen at Leonardslee.
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