Grey-bellied Brent Goose Branta (bernicla) ?nigricans

Most authorities including the IOC World Bird List (version 11.2, 2021) do not currently recognise this taxon despite it being quite distinct in appearance. In the event that is formally recognised in future, the scientific name nigricans would be assigned to it and Black Brant (currently nigricans) would become orientalis.

Grey-bellied Brent Geese normally winter in and around the Paget Sound on the west side of North America, but vagrants have occurred in western Europe, either among Brent Geese or, as with the one shown below, with Pink-footed Geese.

The identification of Grey-bellied Brent Goose - in particular this Grey-bellied Brent Goose - was covered brilliantly by James McCallum in British Birds 113 (September 2020) pages 515-532.

adult Grey-bellied Brent Goose (with Pink-footed Geese), Fring (Norfolk, UK), 1st January 2020

adult Grey-bellied Brent Goose (with Pink-footed Geese), Docking (Norfolk, UK), 28th December 2018