Fruit eating birds are great seed dispersers. Small seeds pass through the GI tract and get depositied hear and there in bird droppings. Larger seeds and pits get regurgitated after the fleshy parts get ground off in the birds crop, and this often results in much larger number of seeds, and all in the same place. Bird behavior determines their movements, and as a result seeds end up in a non-random distribution. This becomes very evident each year when the weeds are removed from under a large bald cypress. Clearly this big tree is a favorite place for birds to roost after having eaten. Based upon the seedlings pulled, a dozen or more for every square foot, wild cherries were a big favorite, following by pokeweed. Other bird dispersed seed include hackberry and black raspberry. Fortunately this tree has a deep accumulation of organic material, and the pulling is easy, if you don't wait too long. Slowly the Phactors are gaining on the weeds, but soon travel will reverse all that. Ah, well.