I guess they correlate it with when those smelly guys start leaving a lot more scent in THEIR woods. Maybe associate it with that human walking into their area ......thinking nothing is seeing, hearing or smelling him. It could also be a couple days after most yahoos sight in their rifles.......or maybe a few days after they see, hear and smell the guys climbing all the trees. Many places.....it's also a couple days (or even THE day) the food starts appearing on the ground.

They'r enot that smart.....but they're far from stupid.