Well I was looking at some bats at a picnic area one day and I got this idea for a minecraft mod. so here it is.

-THE BETTER (AND MORE) ANIMALS MOD-
currently there are birds and bats. more might be added.
list of bats:
(all bats are neutral and don't drop anything)
-Flying fox: spawn in big groups (10-20) they roost in trees by day and at sundown they all fly off, only to come back in the morning.

-Vampire bat: spawns in small groups (3-5) and roost in trees by day and "suck blood" from pigs, sheep and cows by killing them. You'll have to protect your livestock!

-Fishing bat: behaviour identical to the vampire bat, if you are fishing at night with a fishing bat nearby, it will try to steal your fish. if you kill it when it steals your fish it will drop it.

-Vanilla bat: now will spawn in open caves in large numbers (10-20), and come out at night then return in the morning.

list of birds:
(all birds drop raw bird meat and feathers)

-Frogmouth: neutral. stays in trees most of the time unless disturbed (like bats).

-Ground parrot: passive. behaviour the same as pigs, cows and sheep, but if hit will fly away.

-Falcon: behaviour identical to that of wolves, except it can obviously fly and not be tamed.

-Kingfisher: behaviour identical to fishing bats, except not nocturnal and doesn't roost in colonies.

-Albatross: passive. stays in ocean biomes. mainly swims, but can walk and fly if attacked.

-Duck: passive. same model as chicken but different texture. swims like the albatross but stays in lakes and rivers mainly. can fly and walk if attacked.

-Vanilla chicken: exactly the same!

Items/blocks:

-roosting box-

place it anywhere, and bats or birds will stay near it at night*. keep your own pets!

-Bird meat-
a name change of raw/cooked chicken.

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*bats and nocturnal birds will stay near it at daytime though.
If I get any more ideas, I'll add them to the blog. If you are a good mod maker, please make this mod if possible.