For real active hunting between say 25-65 degrees I wear a pair of mesh BDU pants made by Columbia, I shopped around and paid 20 or 30 bucks for them 5 or 6 years ago. They are extremely light, breezy, and tough. I've worn the heck out of them over rocks, crawling around, etc, and still no holes, just popped a button once. When its wet they dry real quick. If its windy or on the cooler end of things I put my rain pants over or put a light pair of capilene long undies underneath or both. Much cooler than above though and I switch to light fleece or wool pants.