European Bison (Bison bonasus, german: Wisent, french: Bison d'Europe). I didn't see them in the wild, only in the animal park next to the nature reserve. (275k)
Here are the pictures of European Bison (Bison bonasus) with links to the pages on which they appear, links to the full sized picture, and the description of the picture with links to the entry in iNaturalist (inaturalist.org)
All pictures are © Dr. Günther Eichhorn, unless otherwise noted.
Poland Nature
Dr. Günther Eichhorn Travel Website
Soaring website