Where would aliens be if they really do exist here on Earth?

I would guess they'd probably be in an area they feel is habitatible.

That's not for me to say.

It's YOUR story. You've already invented fictitious aliens. Now you can go ahead and make up all the fascinating details of why they're here, where they live, what they eat, what they like to do in their spare time, how they like it here, what they do when it's raining, what their plans are, what they think of us, and why nobody has ever seen or heard one.

If you can get it published, I'd buy it.