hogs turning feral

I've got a ranch I bought in 2004. When I bought it, it had some hogs on it mostly all reddish brown or black. Right after I bought the place Tyson turned over a truck load of young hogs. They let them all go, they don't keep anything that has touched the ground. For several years I had a lot of predominantly white as well as red, brown, black and spotted hogs. As they have bred and been trapped and hunted, most of the hogs have gradually gone to mostly black with some spotted, some red and an occasional white. After the Tyson event the hogs had shorter snouts, smoother coats and were more compact and meaty. Now you occasionally see boars that you would swear were Russian. I don't think anyone would transplant hogs here as there were plenty in the first place. My only conclusion is they change their physical structure and color fairly rapidly. In my country the hogs stay pretty fat, but I don't have many really large hogs with the exception of an occasional lone boar. Some of them are really big and rangy. So far my dogs haven't gone life or death with one, although I have had neighbors kill them in the 400 pound range and most of them are runners. Take from this what you want, but hogs change in a hurry.