Complex sentence: Animal life is abundant with several species of endangered animals thriving in the area, among them bears, wolves, wild boar, beavers and lynx as well as deer and Polish bison (around 100 of these live in the Bieszczady Mountains).
Split into simpler sentences: Animal life is abundant with several species of endangered animals thriving in the area. Among them-bear, wolf, wild boar, beaver and lynx as well as deer and Polish bison (around 100 specimen live in the Bieszczady Mountains).