I agree with above comments; the singular of both names is taken - natureforum.com and wildlifeforum.com, and both seem a little more prime (sometimes the 's' makes the name, sometimes it doesn't; in this case I'd say not).
The good news is that neither of those sites is developed, they're both parked with a few uninteresting links plonked on them... so if you develop in any way, you'll be holding the good ball.