海狸不仅外形可爱，而且还是动物界的天才建筑师呢。它们会利用自己“伐木”的本领，在水中将大量的树木堆积起来形成巢穴，躲避捕食者的攻击。秋季是海狸修补大坝的关键时期，因为冬天来临时，湖面将结冰，海狸无法再切割和移动树木，但可以在冰下取食储存的食物，所以每年秋天，都是海狸最忙碌的季节。
A beaver can fell a cottonwood tree in just a few hours, hundreds in a year.
The beaver doesn't chew through the whole trunk, just enough to make the tree unstable.
It then retreats and lets the wind do the rest.
It cuts branches into more manageable lengths and then swims them down a network of purpose-built canals towards the dam.
The pond gives this beaver protection from predators and the canals allow it to forage far into the forest, carrying many times its own weight with ease.
Autumn is the busiest time of year for beavers.
It won't be so easy to make repairs when the pond is frozen over.
The sound of running water is their stimulus to shore up gaps with timber and plug leaks with mud.
But the dam not only serves the beavers.
Moose come here from the forests around to feed on weeds that thrive in the beaver's shallow pond.
