Thomas, have you considered the possibility that the Branta parent is actually Branta hutchinsii, i.e. Richardson's Cackling Goose. The bill shape seems a perfect match for that taxon, and the small size of the bird would seem to favor a hybrid combination involving two small species. A hybrid between a small and a large speciesshould yield a small offspring only 25% of the time assuming that size is under the control of a single gene and that the rules of Mendelian genetics are followed. Anyway, it is a cool bird for sure! - Nick Komar
