Snowy Egret-Little Blue Heron hybrid?

Jeff Lewis photographed this peculiar heron that appears to be either a hybrid between Snowy Egret and Little Blue Heron, or a partially melanistic Snowy Egret, on 27 January 2005 in South Nags Head (at the site where the White-faced Ibis was seen a couple of years ago). Update: the third photo was taken 19 March 2005.