Cats Forever
Might be related to the number of members that never make a post. About half of the members never make a posting so it might be that group didn't see any value in "re-upping" on the new board. Just a thought!!
With the email verification it takes a little effort for someone to be a "member" and some don't want to put forth the effort. My 2 cents.
I don't like to ask but how many were bothered by the squabling on the old site and chose not to re-up.