The subject has shifted slightly but it's an area that is significant around me. We live between two estates: one very large one (a few thousand acres) and a much smaller one (probably a few hundred acres) and they both run shooting parties, but according to my neighbours, only the large estate breeds/stocks the pheasant and partridge. What the smaller estate does do is put feeders on their land. Now there's no reason to do this other than to 'encourage' the large estate's birds across, and as much as I dislike the whole shooting for pleasure malarkey, I also recognise that luring livestock onto their land is dubious, and yet nothing has been done to stop it.
When the birds are on my land I consider them as wild birds - they're not mine but the owner has no right to take them off my property - but when they're on the road, or any other persons land around here, they seem to be 'fair game' for anybody. I do wonder who owns them once they've been 'set free'. Perhaps that's precisely what has happened: the breeder has released them from their ownership.
It's an odd arrangement, but like so many other aspects of country life, things aren't always clear cut. I seem to discover a new example on a weekly basis. If my dogs didn't insist on chasing them I might just encourage a few to stay around.