yep, that would be stealing

If you're tracing them, that's a no-no. Honestly there are only so many ways to draw a nose/tail/wing. I'm going to say that combining things you've seen in other works if you've not traced them is probably fine, though if you're referencing something that's very unique and an idea you probably could not have come up with on your own, it's always nice to ask the artist for permission.

I'm fine with people referencing my art, though if it ends up looking incredibly similar to my image, I do ask that reference credit be provided.