Probably the same reason why there are no wild pheasants left in Pa. The state game officials don't seem to care much about small game, especially game birds, just about the big game, deer, and bear here.
Some of the big bird states, South Datkota as one, there is millions coming into their revenue from mostly bird hunters, let the bird population dwindle by loss of habitat ,etc and they loose that revenue, there will be heads rolling. Here they don't care, industry and the people pay the taxes, not the hunters money.

David