If bucks are rubbing their antlers on trees with a lot of sap, then the sap sticks to the antlers and they get darker, he said.
Bucks on the prairie, which spend more time in the sun, tend to have whiter antlers because their antlers get bleached out by the sun, Bartholomew said.
Bucks rub their antlers on trees primarily to mark their territory, he said. They start making rubs or scrapes once the velvet has shed from the antlers, he said.
Oklahoma's 16-day deer gun season, the biggest hunting season of the year, opens the Saturday before Thanksgiving.
Almost 200,000 hunters in Oklahoma participate in the deer gun season. Archery deer season remains open through Jan. 15.