Hi Suzie. We are not sure. Since the Black Swan is the native species, we would surmise that the white swans are feral flock members that escaped from their captive settings and started a new flock. This coupled with actual captive white swans, there would be no solid record of how many now exist. Your local wildlife entities may have this answer since most will keep bird counts and will report wild non native flying swans as they are observed. The Regal Swan