I’d just turned the calendar to September, but the photo in my newspaper said peak rut. Just after Labor Day last year, a local farmer found a pair of big dead bucks with their antlers locked. Such a sight struck many deer hunters as odd. Why would such a heated battle occur so early in the fall?

But my friend Ted Marum, a seasoned whitetail guide, wasn’t surprised. “I’ve watched maybe a dozen knock-down, drag-out buck fights,” he said when I showed him the picture, “and over half of them occurred in September. It’s a time when bucks can be very aggressive.

“For the first time in months, a buck’s velvet is gone and his testosterone levels are rising. If he’s got an attitude, he’s now got hard antlers to go with it. Put him next to another belligerent buck, and there’s going to be a brawl,” Marum explains. “Also, as summer bachelor groups break up, bucks begin establishing home core areas for the fall. As they disperse, they bump into competing strangers–and sometimes they duke it out.”

SET UP A SCRAP This is important information for early-season hunters, who typically focus on silently ambushing bucks that are predictably traveling to food sources. “Most guys are afraid to rattle and call now, thinking the sound is unnatural,” Marum says. “In fact, deer not only hear fights all the time now, they participate. I tell my hunters to blind call and rattle on every early-season hunt. And if they see a big buck, calling can bring him in.”

I took this approach a step further on a September hunt two years ago on Marum’s home farm. Marum and I had agreed that I should stake a buck decoy near my stand and try to punch the aggression buttons of any whitetail out of bow range. With shooting light waning, a good buck appeared in the field. I grunted to attract his attention. When he looked my way, he saw the “intruder” and rushed in to investigate. The buck wound up in the back of my pickup–only because I challenged him.

THE CLASH: Bucks start fighting long before the rut. So get aggressive now.