Because just as your creatures can adapt to every biome, why wouldn't other animals?
Bunnies
It never made sense to me how bunnies are white everywhere. Here are some different variants:
Grassland Bunny, which looks like it's current appearance but brown. It replaces the current white bunny.
Arctic Bunny, white and with a fluffy tail. They have 1 defense.
Savanna Bunny, a regular bunny but beige, and has 1 stealth.
Swamp Bunny, a black bunny that can safely eat poison berries. (Because I don't think swamps should be exempt from bunnies being a nusiance.)
Balance Bears
Just in case you thought there were no truly invincible predators on Deadly Hills.
Brown Bear, a grassland version of the balance bear.
Bearyenas
Because Deadly Hills isn't the only killer island out there, what if the non-killer bearyenas were slightly more dangerous?
Mountain Bearyena, which is white. It has cold resistance, and has 1 defense and 3 strength. It spawns in the Frost Lands.
Jungle Bearyena, which is slightly smaller. It has stealth and scentless, so it's harder to hear/smell. It spawns in the Deep Jungle.
Ramfoxes
The concept of a predator that spawns in a pack is interesting to me, I'm not sure if it should be limited to one biome.
Red Ramfox, spawns in the grasslands on islands that aren't easy, not counting Home Island or Crossing.
Savanna Ramfox, spawns on islands with hot climates. They are beige with large ears.