Anyone know of a Nature Recording message board similar to TS?
Well it's a yahoo group so it's all email:
<naturerecordists@yahoogroups.com>
Not sure about a website like TS for nature recordings but those people have a lot of knowledge but be prepared for a lot of emails.
Yahoo Group nature recordists
It's also worth looking at the website of the Wildlife Sound Recording Society (WSRS) (http://www.wildlife-sound.org/).
They are a knowledgeable and helpful lot.