They are very susceptible to pollution as well.
I found a native tree frog in our back yard as a kid. Smaller than a quarter (or Brit. tuppence) and bright, new-leaf, it-can't-really-be-this-color green with a pale yellow stomach and red eyes. He wasn't afraid at all when I picked him up. He just hopped up my arm t a n angle about 30% off vertical.
He, or she of course I didn't ask, looked more like a design for an animated character than a real animal.