A Beavers vary their dwellings according to local conditions.The inner chamber of their mound dwelling is positioned according to the level of the river in which it is situated. Once the mound is built the water rises up to meet the lodge or dwelling. During construction they dig an upward sloping tunnel into the riverbank which ends in a larger chamber underground about three feet across and two feet high. There is also usually a feeding chamber located near the entrance . Feeding generally occurs at night inside this chamber or outside on the river's edge and all food thrown away from feeding is disposed of directly into the water. Download to read ad-free B Another strategy is to attach the structure to existing trees or large rocks and further support these by heavy stones brought to the site. Gaps in the wall of the dam are filled with smal I branches leaves and other small materials and covered with mud or clay to make the dam completely water tight. The walls of the underwater entrance are smooth and steep. In front of the entrance is a clever deep pit where materials are gathered The pit also acts as a water current prote ction by reducing the speed and force of the water, protecting the structure. and repair the damage. Their mounds can reach a height of six to ten feet with hollowed-out living chambers inside,and entrances below water level.The largest recorded dam is in the Voronesh region of the former Sovie Union and measured about 3.800 feet long. 3 feet high and wide. In the swamps of the Mississippi basin and the Jefferson River in Montana beavers build dams over a thousand feet long which are strong enough to carry a person on horseback! C When the surrounding water level rises. threatening its home,beaver s have several options.They can go to the source of the problem - the water-and lower the top of the dam where the water runs over, thus lowering the water level. If this is not enough, they can remove chewed materials from the ceiling of the structure to build up the floor.Similarly, soil and small branches can be used to create a thicker and higher floor level. If the water level continues to rise, more twigs and mud can be added to the origina I structure. The main chamber can also be dug out further up. keeping the same angle of entry. In some areas, as in shallow,slow moving ponds,the beaver creates an island of and mud.If a hole develops in the dam they immediately find D Few species have the ability to manipulate the environment to their own ends as the beaver does. The dam.lodge, winter food store canals and runways are all part of a completely designed environme nt. The beaver and its dam, which at first might seem to be destructive rather than constructive.have wide effects on the ecology of the surrounding countryside. The dam raises the water table and slows drainage at the base of the dam by maintaining a steady flow of water in headstream s. The dam also prevents so I from washin downstream . And the rich soil that builds up soon supports a variety of plants that will attract other animals . Similarly, the systems of dams and pools provide food and habitat to other creatures, which in turn attract predators and the whole web of life is enriched. Questions 11-13 : Short-ans wer questions Answer the questions below . Choose NO MORE THAN TWO WORDS AN ID/OR A NUMBER from the text for each answer. 11 What is the maximum height that mounds can reach? __ 12 Which structure made by the beaver brings benefits to the local countryside? __ 13 What do the dams and pools provide for other animals? __