Because flocks of feral Quakers have established themselves in many States ( I think the biggest flocks are in California and Florida). There's a huge flock in New York City's Central Park, so cold winters don't deter them. They build their huge nests on utility lines. People are worried they are harming native species and crops. I believe they've been spotted in every state around WV so I'm getting worried! Some States have a grandfather clause for people who already own one, but some just make you get rid of them.
Some argue that they will fill the niche that the Carolina Parakeet left when they went extinct... But, apparently, that argument isn't working!