中国新疆北部，阿勒泰地区，连绵的阿尔泰山脉和广的古尔班通古特沙漠，占据着一片干旱、蛮荒之地。可是，在它们之间，兀然出现一片绿洲。这就是乌伦古河及其支流，在荒漠中流淌出一片狭窄却树木葱郁的绿色走廊。这条神奇的河流不仅给众多生灵提供了珍贵的水源，还庇护着一种行踪隐蔽的珍稀动物，它们就躲藏在幽暗的水面之下。这是一种啮齿动物，却长着像鸭嘴兽一样的扁尾巴。

它们胆小、笨拙，需要黑夜的隐蔽才敢放心出没，却有着神奇的天赋，能够改造自己的生存坏境。这就是河狸，动物界的建筑大师，而在新疆阿勒泰，生存着这个物种最神秘也是最濒危的一支。

In Altay Prefecture, Northern Xinjiang Uygur Autonomous Region of China, Altai Mountains and Gurbantonggut Desert cover a stretch of land of drought and wilderness. However, there is an oasis between them, which is the narrow yet densely wooded green passage that was made by Ulungur River and its tributaries. This magic river not only provides water to many creatures in its drainage basin, but also provides shelter to a rare animal who hides under the dark watersurface. They are rodents but have flat tails like Duck-billed Platypus. They are so timorous and clumsy that only the darkness can make they feel safe enough to go out, but they have magical talents of remodeling their habitats. They are beavers, maser architect of the animal world. In Altay Prefecture of Xinjiang lives the most mysterious and endangered type of this species.