Cicada: Food, curio, loud noisemaker to unleash upon your friends and enemies. Rare chance to be infected with Massospora, which makes it a much better curio. Cicada young can be found while digging, cicada shells can be found when gathering bark. Spawns on any forest terrain.
Puffin: Adorable birds. Beaks are curios that can be found while butchering or as a forageable (Puffin beaks are only colorful during breeding season, the outer shell is shed afterwards). Spawns on ocean and skargard.
Great Auk: Great big beautiful extinct birds. Very rare in game to represent this? Spawns on ocean and skargard.
Pine Marten: Relative of the stoat, badger, and otter. Small but aggressive. Spawns in forests.
Mink: Another long furry animal. Furs can be crafted into Mink Shawl. Spawns on freshwater and beach.
Wisent or Zubr: European bison. Horns are curios and bone material. Travels in passive herds. Entire herd will fight if one is aggroed. Can do 'pull hair' for a nice curio, but has a high chance of angering them. Spawns on grassland terrains.
Olm: Europe's only cave-dwelling vertebrate. Looks like a cross between an axolotl and a worm. Cave curio that spawns in water.
Giant Bats: Rename of the bats already present in game, no other changes. Irl bats are not aggressive, and I find it odd that video games often have them as enemies.
Barbary Macaque: Apparently these were once widespread in Europe's prehistory and lived as far north as England. Aside from humans, they are Europe's only primates. Today's European population is only found at the opening of the Mediterranean Sea. Monkey Tail is a relatively common curio received while butchering. A much rarer find is the Monkey's Paw, an extremely valuable curio. While being studied, it inflicts a terrible curse that triples all damage received, and doubles any damage already present. The curse is lifted about a day after study is finished, or when the paw is removed from the study report.
Bonus!
Mouse Nibbled String: Leaving a rope in a container for a long time has a chance to spawn this curio, as long as there is at least one empty spot for it. Ropes can spawn these several times before being destroyed. Low quality containers have a better chance of spawning Mouse Nibbled String, while high quality containers will prevent them.