Bean goose

The bean goose is a goose that breeds in northern Europe and Eurosiberia. It has two distinct varieties, one inhabiting taiga habitats and one inhabiting tundra. These are recognised as separate species by the American Ornithologists' Union and the IOC (taiga bean goose and tundra bean goose), but are considered a single species by other authorities, such as the British Ornithologists' Union. It is migratory and winters further south in Europe and Asia.

Bean goose
Bean goose at Slimbridge Wildfowl and Wetlands Centre, Gloucestershire, England

Least Concern  (IUCN 3.1)[1]
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Aves
Order:
Anseriformes
Family:
Anatidae
Subfamily:
Anserinae
Tribe:
Anserini
Genus:
Anser

Brisson, 1760
Species

Taiga bean goose (Anser fabalis)
Tundra bean goose (Anser serrirostris)

Description

The length ranges from 68 to 90 cm (27–35 in), wingspan from 140 to 174 cm (55–69 in) and weight from 1.7–4 kg (3.7–8.8 lb).[2] In the nominate subspecies, males average 3.2 kg (7.1 lb) and females average 2.84 kg (6.3 lb).[2] The bill is black at the base and tip, with an orange band across the middle; the legs and feet are also bright orange.

The upper wing-coverts are dark brown, as in the white-fronted goose (Anser albifrons) and the lesser white-fronted goose (A. erythropus), but differing from these in having narrow white fringes to the feathers.

The voice is a loud honking, higher pitched in the smaller subspecies.

The closely related pink-footed goose (A. brachyrhynchus) has the bill short, bright pink in the middle, and the feet also pink, the upper wing-coverts being nearly of the same bluish-grey as in the greylag goose. In size and bill structure, it is very similar to Anser fabalis rossicus, and in the past was often treated as a sixth subspecies of bean goose.

Taxonomy

The English and scientific names of the bean goose come from its habit in the past of grazing in bean field stubbles in winter. Anser is the Latin for "goose", and fabalis is derived from the Latin faba, a broad bean.[3]

Taiga bean goose (Anser fabalis sensu stricto) on background, tundra bean goose (Anser serrirostris) on foreground and greylag goose (Anser anser) on the right, at Spaarndam, Noord-Holland, the Netherlands
A flock of tundra bean geese

There are five subspecies, with complex variation in body size and bill size and pattern; generally, size increases from north to south and from west to east. Some ornithologists (including AOU 2007) split them into two species based on breeding habitat, whether in forest bogs in the subarctic taiga, or on the arctic tundra. The taiga and tundra bean goose diverged about 2.5 million years ago and established secondary contact ca. 60,000 years ago, resulting in extensive gene flow.[4]

Taiga bean goose (Anser fabalis sensu stricto) (Latham, 1787)
  • A. f. fabalis (Latham, 1787). Scandinavia east to the Urals. Large; bill long and narrow, with broad orange band. Anser fabalis fabalis is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies.
  • A. f. johanseni (Delacour, 1951). West Siberian taiga. Large; bill long and narrow, with narrow orange band.
  • A. f. middendorffii (Severtzov, 1873). East Siberian taiga. Very large; bill long and stout, with narrow orange band.
Tundra bean goose (Anser serrirostris, if treated as a distinct species) (Gould, 1852)
  • A. s. rossicus (Buturlin, 1933). Northern Russian tundra east to the Taimyr Peninsula. Small; bill short and stubby, with narrow orange band. Anser fabalis rossicus is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies.
  • A. s. serrirostris (Gould, 1852). East Siberian tundra. Large; bill long and stout, with narrow orange band.

Distribution
Egg, Collection Museum Wiesbaden

The bean goose is a rare winter visitor to Britain. There are two regular wintering flocks of taiga bean goose, in the Yare Valley, Norfolk and the Avon Valley, Scotland. A formerly regular flock in Dumfries and Galloway no longer occurs there. The tundra bean goose has no regular wintering sites, but is found in small groups among other grey goose species – among the most regular localities are WWT Slimbridge, Gloucestershire and Holkham Marshes, Norfolk.

The Taiga bean geese Anser fabalis fabalis wintering in Europe are considered to migrate across three different flyways: Western, Central and Eastern; which has been confirmed by stable isotope analysis of their flight feathers.[5]

References
  1. BirdLife International (2012). "Anser fabalis". IUCN Red List of Threatened Species. 2012. Retrieved 4 January 2015.CS1 maint: ref=harv (link)
  2. Dunning, John B. Jr., ed. (1992). CRC Handbook of Avian Body Masses. CRC Press. ISBN 978-0-8493-4258-5.
  3. Jobling, James A (2010). The Helm Dictionary of Scientific Bird Names. London: Christopher Helm. pp. 48, 157. ISBN 978-1-4081-2501-4.
  4. Ottenburghs, Jente; Honka, Johanna; Müskens, Gerard J. D. M.; Ellegren, Hans (26 May 2020). "Recent introgression between Taiga Bean Goose and Tundra Bean Goose results in a largely homogeneous landscape of genetic differentiation". Heredity: 1–12. doi:10.1038/s41437-020-0322-z. ISSN 1365-2540.
  5. Fox, A. D.; Hobson, K. A.; de Jong, A.; Kardynal, K. J.; Koehler, G.; Heinicke, T. (2017). "Flyway population delineation in Taiga Bean Geese Anser fabalis fabalis revealed by multi-element feather stable isotope analysis". Ibis. 159 (1): 66–75. doi:10.1111/ibi.12417.

Further reading

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