Changes to the British List (29 November 2021)

The British Ornithologists’ Union Records Committee (BOURC) has made the following change to the British List:

The following species has been added to the British List:

Ross’s Goose Anser rossii
One, adult, Plex Moss, Lancashire, 5 December 1970 to 17 January 1971 and consecutive winters to January 1974.

Photo (right) stock image by Andrew C taken at Dayton, Ohio, US 24 January 2017 | CC BY 2.0 Wikimedia Commons

Ross’s Goose had been placed in Category D of the British List for many years, as there have been uncertainties about the origins of birds found in Britain because the species is kept widely in captivity and escapes are known to occur.

However, the species is a long-distance migrant in North America and there is much precedent for Nearctic wildfowl, including geese, to cross the Atlantic naturally and be found in Europe. Furthermore, the very significant growth and expansion of the population of Ross’s Goose since the 1950s has increased the probability of such trans-Atlantic vagrancy.

Part of the BOURC remit and procedure is to periodically re-examine species in Category D. Following published BOURC guidelines created to judge the status of wildfowl (British Birds 113: 46-53), BOURC considered a number of records of Ross’s Geese. Following these criteria, this 1970 Plex Moss record was found by the majority of BOURC (7:1) to be eligible for Category A. This record occurred during a period of rapid population growth of the species, and in circumstances highly suggestive of wild origin. Another important part of the process was to confirm the identification of this 50-year old record on the basis of the original field notes along with photographs. These documents were located and BOURC decided unanimously that the identification was secure. Hence the 1970 Plex Moss was accepted as the first British record and the species accepted to Category A.

Ross’s Goose should be placed after Cackling Goose Branta hutchinsii on the British List.

Ross’s Goose breeds in northern Canada and migrates to winter in southern and western USA and northern Mexico. A significant and dramatic increase in the population has occurred since the 1950s, an estimated 8900% over the past 40 years, with the species now classified as Least Concern by IUCN.

This change will be published as part of the BOURC’s 54th report due to be published in IBIS in July 2022.

Upon publication of these changes, the British List stands at 628 species (Category A = 610; Category B = 8; Category C = 10).

View the British List