Hello Gingernut,
Prairie only resets if you fail a Tame attempt but as you can see in your screen shot
You have the Free Attempt so you can tame at Clover level for free.
If It had a cool down timer there instead of the "Free Tame" that would cost Gold to Tame.
Here is a guide on Prairie for you:
http://forum.amzgame.com/thread/detail?id=11874