Oh yes we do...you seem to think animals don't influence their habbits...that is false.
Go live in cave if you truely believe that...I dare you.
Humans have reduced the population of the Asiatic lion to a few hundred currently living in a small area of India. They have wiped out, or will wipe out, other species etc. I know I'm sounding like a hippie or whatever, like the other posted called me, but I don't see any other species besides humans inflicting such devastation on the earth. I'm sure animals influence their habitats (I think that's what you intended) but not to the degree that humans do.
We are living against nature rather than with it.
If I were not living in a average sized city with proper housing then maybe I might have to live in a cave. But to live a so-called "green" lifestyle just for its sake has no meaning.