I'm thinking somethign in their habitat has changed? Food source and pressure are usually the culprits and sicne you've indicated there has been little in the way of other hunters perhaps their food source has changed? Do you see any sign, fresh tracks, droppings, rubs, scrapes? has a another food source nearby become more attractive to them. I find it interesting there are less hunters in the woods, perhaps they too have realized there is little activity and have moved on?