Animals haven’t changed a lot in the last thousand years, but human use of them has shifted, and thus they too have changed somewhat. We can divide animals into six useful categories: wild animals, farm animals, horses, pets, exotic (zoo) animals, and imaginary animals. I think I’ll pass over ocean animals for now.
Of course, animals are also categorized by geography, so by talking about “medieval” animals, we’re really focusing first on Europe, second on the Islamic lands of North Africa, the Middle East, and Central Asia, and third on the far East of China, India, and the islands. The Americas and Australia obviously existed and had animals. I won’t include them, though, because to say “medieval” means essentially, “what can be gleaned from medieval books that were available in the cities within a few hundred miles of the Mediterranean.” There was a large trade zone between London and Beijing, connected by the Silk Road and ocean, with Constantinople roughly in the center. Outside of that zone, “there be dragons”—-or perhaps anything from two-headed dogs to talking lizards.
To go back to medieval Europe, Asia and Africa would be to find a paradise of wild animals, compared to our tamer, less diverse world now. Because Africa remained wild until 100 years ago, we have a pretty good sense of its animals. The Nile was full of crocodiles (gone now) and both Sahel and Savanna were the domain of lions, gazelles, jackals, and our favorite big game animals: elephants, giraffes, and zebras. Some parts of Asia are not much altered, for example, Siberia with its tigers and wolves or the Chinese highlands with pandas. But Europe and the Middle East have altered a lot.