American Goldfinch - Beginning in September, they molt all of their feathers, ending up with a pristine set of feathers (and drab colors). In the spring, the males transform into bright yellow breeding plumage, but the wing and tail feathers remain from the previous fall. As these wing feathers get older the pale buff edges fade to white and disintegrate, so that by the end of the summer the wings look essentially all black. And in September another complete molt begins.
The habitat of the beaver is the riparian zone, inclusive of stream bed. The actions of beavers for hundreds of thousands of years in the Northern Hemisphere have kept these watery systems healthy and in good repair, although a human observing all the downed trees might think that the beavers were doing just the opposite.
The beaver works as a keystone species in an ecosystem by creating wetlands that are used by many other species. Next to humans, no other extant animal appears to do more to shape its landscape. Beavers potentially even impact climate change.
Beavers fell trees for several reasons. They fell large mature trees, usually in strategic locations, to form the basis of a dam, but European beavers tend to use small diameter (<10 beavers="" cm="" especially="" fell="" food.="" for="" nbsp="" p="" purpose.="" second-growth="" small="" this="" trees="" young="">10>
Broadleaved trees re-grow as acoppice, providing easy-to-reach stems and leaves for food in subsequent years. Ponds created by beavers can also kill some tree species by drowning, but this creates standing dead wood, which is very important for a wide range of animals and plants.