I hate to be the voice of doubt, but they ARE an invaise species in that location. The native fauna are being out fed and out bred by them. These aren't "wild" as much as a domestic bird who have been released (illegial as heck), and have displaced the native ducks in the ecosystem. Everytime someone has "lost" a domestic animal, there's a chance that you've upset the natrual balance. This is a problem that is man-made, just as feral hogs were a man-created problem. Yes ducklings are cute, and 400lb hogs are not, but you can not choose to let an invasive species continue off of "cute" factor. Yes in therory, you can go and "save" a few of them from a pond, and so long as you agree to keep them under your direct control, that's just fine. Now I happen to like muscovies, but they should be kept under controlled enviroments, not released to breed nonstop in a park. The city has determined that 110 birds will die, so they will exterminate 110 ducks. Do you think that they'll just shrug and go away? or do you think that they'll keep looking till they get thier 110. Save the few you can if you'd like, but realize that you're responsiable not just for that bird, but for all of the offspring it may have.