That new rule is there because the people who are making their sigs the hard way are complaining that some of the other sig entries are just really large pics that have been cropped and fixed and that lowers the standard of the contest. I mean look at what happened last month and the month before. Lots of entries but with only 3 or 4 entries with the major vote, and with first place usually taking a large chunk of the votes, all of them have been made using renders and stock and usually from scratch. The other sigs barely get any votes at all. This rule is there to make sure nothing easy gets through to the voting. A bit harsh but I think its worth it. I mean come on, if I made a bad sig and saw it only get one vote, which came from me cause I'd vote for mine no matter what, then I would feel bad that I did such a horrible job. In a sense we won't let the bad ones have a chance at feeling bad.
As for the theme, if you cant find an animal and put it in your sig you are really overestimating the word "nature." Its really simple you just need to think about it a bit more. Also it doesnt have to be a real life render it can be animated as well, as long as the theme is nautre-like then its ok.
The winner of the May Sig Contest, Spirit!!