Here is my suggestion for the follow up on bats.
-Bats cannot land, only in dens.
-Bats have 1, very rarely two babies
-Bats can carry two things at once, maybe one could be a slot only for offspring? Bats carry offspring on the back and could carry stuff in the mouth.
-Could use echolocation to find bugs (Insectivore)
-Could land on a sleeping animal or a large herd and select "Drink Blood" (Vampire)
Could eat berries and nectar (Fruit bat)
-Make dens in special type of cave or branch
-No nests made
-Basic is more reasonable, but advanced is alright
Picture on what caves could look like