Animal spirits, which include Fox spirits (like Kitsune and Gumiho), Cat spirits (like Nekomata and Bakenek, of which Byakko could be part of), Bat spirits like Kuronue, and bird spirits like Murugu, tend to differ a bit from their animal counterparts.
While you have normal animals like those you find in the human world, they may have some mutations from being in Makai for generations. These differ from a Spirit who has gained some degree of sapience, enough to utilize its powers, speak the local or common tongue.
Mere animals might have have special abilities (and you could reference the Fire Rats mentioned in Inuyasha, which are implied to be large rodents that are immune to fire), like mild invisibility or unique poisons, attributes in its fur or blood, or simply be more aligned to elements and use that in its day to day life, but unless they encounter something that pushes enough magic or energy into them to prompt them into Sapience, they will remain a normal animal. The fox and cat species are notable for this, both having abilities to gain sapience and unlock new powers if they survive to an ancient age, and in Makai this is also if there is a spot that teems with energy.
Animal Spirits, who tend to gain demonic energy and abilities, tend to be more omnivorous, while still having preferences that echo thier species. More foods open up for them that were previously toxic, and usually only cause mild indigestion if anything. A deer spirit or rabbit spirit will still prefer grains, nuts, and greens over meat, but now can eat such and get nutrition out of it. A carnivore like a fox or wolf can eat more greens, enjoy a more diverse diet, but retain the ability to eat a carcass easily.
A spirit can also have more of a chance to gain enough power through personal gain or genetics, to be able to shift form to keep thier true animal shape or a more humanoid appearance.
To bring Kuronue into the mix, most species of bats are ones who drink nectar, and a smaller portion hunt insects, while a smaller still eat fruit, frogs, or blood. The Bat folk as a whole vary a lot on what they eat, but meat eating is near universal. As such it is difficult to place the Bat spirit lineage from any set modern bat species.
Odds are high, through, that Kuro is roughly descended from nectar or fruit bats, and has a sweet tooth common in his kind. He can eat meat very happily, but may prefer sweeter meats, demons with high sugar in thier diet or a glucose imbalance. But on the whole, this bat will not be looked askance at if he raids the pies from the palace's table during a raid, or the cook's honey jar. Its just how bat species can be.
This results in Youko's forest having patches of safe to eat berries, and several fruit trees.