河狸是动物界数一数二的高明建筑师。这些辛勤的工程师们,以擅长搭建跨越河川、溪流的水坝而闻名。水坝能拦截河水,在河道蓄积出一个池塘,提供河狸建筑巢穴的合适环境。住在这种巢穴里很安全,不必担心敌人会侵入,因为所有的出入口都位于水中。虽然河狸的家是用树枝和淤泥筑成的,但屋顶却非常坚固,就算凶猛有力的大灰熊也难以踩破闯进去。以前,在北半球的所有森林里几乎都看得到河狸的踪影,可是现在只有加拿大和美国境内比较常见。 Beaver is the finest architect in the world of animals. These hard-working engineers are famous for their expertise in building dams that span rivers and streams. The dam intercepts the river, accumulates a pond in the river and provides a suitable environment for the beaver's building nests. It's safe to live in this nest, without having to worry about the enemy going in because all the entrances and exits are in the water. Although the beaver's home is built of branches and mud, the roof is very strong, even if the mighty gigantic grizzly bear is hard to break into. In the past, beavers were almost always visible in all forests in the northern hemisphere, but are now more common in Canada and the United States.