Gorgeous but, unfortunately, this was not part of the mixed Whitefront flock referred to above. Have seen a proper one at Slimbridge though,... in 1995, just before the combination of tragic population decline and farcical reintroduction gubbins (including the release of birds "contaminated" with Whitefront genes!?) turned the species into a mythical/untickable enigma.
Leucistic Pintail, just one of the many gems you can bump into whilst wandering the highways and byways of restricted gene pool land.