How i think passive mob AI could be improved massively (Hunger)

OK here goes, i think each passive mob should find their own food

Chickens- Occasionally pluck long grass to get seeds.

Cows- Either eat grass like sheep/eat randomly generated hay bales?

Sheep- Eat grass

Pigs- Eat anything

Ocelots- Eat Chickens

Bats- Maybe catch fish?

Mooshrooms- Eats mushrooms, and mycelium.

Squid- Maybe coral?

Villagers- Like us, make their own food.

EDIT: If a mob spawns in a biome they wont survive in, they will migrate to the appropriate one in a big group.