The North American Nature Photography Association is a great group for all amateur and professional nature photographers. I am on their board, and love what they do.
NANPA has started a Meetup program to get nature photographers together at the local level using meetup.com as the communication system. It is great fun, and I am leading the Meetup group for North Texas.
The NANPA North Texas Meetups are generally free and open to everyone (not just NANPA members). Get together to shoot in great local spots, meet folks with similar interests, and perhaps learn a bit in the process.
So if you are a nature photographer in North Texas, join our Meetup group and come on out! And help us spread the word to those you think might be interested, too. If you are not in North Texas, do a search for NANPA on Meetup.com and see if there is a group near you. There are already groups in Austin, Houston, South Texas and many other locations across the country.