>>27427666It appears to be a barn owl. I'm sure it is also based on something else. I don't know where the Grass typing comes into play, but that might be more evident when it evolves.
Barn owls are notably common in the British isles, as they sometimes hunt during the day there. I think Rowlet looks a little British on purpose because of this. Its English name COULD partly be a reference to J.K. Rowling that someone on the English translation team snuck in there, but that might entirely be a coincidence.
