HUNTING TRIGGERS HERD GROWTH. It’s simple science: When part of the animal population is removed, new animals migrate in, or the remaining population rebounds due to food abundance. The deer propagate and the population increases. Since hunters always want more deer to shoot, they kill bucks over does. Pregnant does left with an ample food supply tend to give birth to a higher ratio of fawns. In most states there are 3 does for every buck. In Michigan and Pennsylvania, there are over 20 does per each buck. With less bucks competing for territory, mating becomes the primary focus of the herd.