The document describes several endangered species in Poland, including the European beaver which inhabits wooded river and lake banks and builds burrows with underwater entrances. It also discusses the dudek, a small vanishing bird that lives on the edges of forests, and the capercaillie which has 5 isolated populations in Poland and inhabits large forests near bogs. Additionally, it provides information on other threatened species such as the European hedgehog, mute swan, weasel, brown bear, bald eagle, dormouse, lynx, wolf, squirrel, and aurochs.