Back when I was living in LA (technically in Eagle Rock, so not the main city but it's all sprawl down there) I was walking to class from my house once and, out of nowhere, a hawk came barreling out of the sky and absolutely annihilated a pigeon on the sidewalk about 40 feet in front of me. We had a coyote that lived somewhere nearby and was a regular sight at night, and there were like 6 species of snake that lived in the easement right behind my college. That's not to mention all the vermin, insects, and other life adapted to living inside and among buildings. And I just imagine that your average fantasy city is less dense and less smothering of the natural world than modern LA.
Yeah an urban druid doesn't sound so impossible to me!
Imagine a half-pigeon-half-housecat urban griffin!!