General terms:
* Forest animal
* Wild animal
* Woodlander
* Sylvan creature
* Fauna
More specific terms:
* Arboreal animal (animals that live in trees)
* Nocturnal animal (animals that are active at night)
* Carnivore (meat-eating animals)
* Herbivore (plant-eating animals)
* Omnivore (animals that eat both plants and meat)
The best word to use will depend on the specific context. For example, if you are talking about animals that live in trees, "arboreal animal" would be a good choice. If you are talking about animals that are active at night, "nocturnal animal" would be a better option.