Justification of Red List Category
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (extent of occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend is not known, but the population is not believed to be decreasing sufficiently rapidly to approach the thresholds under the population trend criterion (>30% decline over ten years or three generations). The population size is extremely large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
The European breeding population is estimated at 280,000-331,000 pairs, which equates to 560,000-662,000 mature individuals (BirdLife International 2021). Across its North American range, newer information suggests that the species numbers 4,300,000 mature individuals, where conversions have already taken place to estimate the number of breeding adults (Partners in Flight 2021). In East Asia, the population across South Korea, Japan and China are thought to number 231,000-283,000 individuals (Jia et al. 2016), roughly converted to 154,000-189,000 mature individuals. To account for additional population structures across the species' flyways (per Wetlands International 2022), a revised global population estimate is therefore placed in the band of 5,000,000-5,999,999 mature individuals.
The overall population trend is uncertain, as some populations are decreasing, while others are stable, increasing or have unknown trends (Wetlands International 2022). This species has undergone a large and statistically significant increase over the last 40 years in North America (Partners in Flight 2021). In Europe the population size is estimated to be stable (BirdLife International 2021).
Behaviour This species is fully migratory, travelling in stages via several stop-over sites between separate breeding and wintering grounds (Madge and Burn 1988, del Hoyo et al. 1992). The species breeds from late-May or early-June in single pairs or loose groups, with moulting non-breeders and failed breeders gathering on areas of open water separate from the major breeding congregations (del Hoyo et al. 1992, Kear 2005). After breeding the species gathers in small flocks (less than 30 individuals) to undergo a post-breeding moult period near the breeding grounds where it becomes flightless for c.25 days (Madge and Burn 1988, Scott and Rose 1996). After this moulting period flocks gather to migrate south to winter quarters, leaving the breeding areas from late-August through September and arriving late in the autumn (Madge and Burn 1988). Outside of the breeding season the species is highly gregarious (large flocks of up to 30,000 individuals are recorded in Europe), although it is more commonly observed in small loose groups due to the patchiness of its favoured habitat (Madge and Burn 1988, Kear 2005). The species usually forages within 20 km of rooting sites, although the optimum distance for foraging areas may be less than this (less than 4 km in Scotland, UK) (Vickery and Gill 1999, Kear 2005).
Habitat Breeding The species breeds in open, low-lying, shrubby tundra on the coast and inland, in close proximity to marshes, lakes, pools, rivers, and willow- and shrub-lined ponds and streams (Johnsgard 1978, del Hoyo et al. 1992, Snow and Perrins 1998). It requires dry slopes, banks, mounds, hummocks or patches of sand or clay for nesting sites, especially those commanding good views of the surrounding area (Snow and Perrins 1998). Non-breeding The species winters in open country on steppe and agricultural land (e.g. improved grassland, stubble fields and wet meadows), or in brackish and freshwater marshy habitats (such as upland bogs, peatlands and floodlands) (Johnsgard 1978, Madge and Burn 1988, del Hoyo et al. 1992, Scott and Rose 1996, Kear 2005). It may also roost on tidal marshes, in sheltered bays or in estuaries and frequents inland lakes and reservoirs in North America (Kear 2005).
Diet The species is herbivorous, its diet consisting of the roots, leaves, stems, seeds and fruits of terrestrial plants such as herbs, grasses and sedges, as well as agricultural grain (e.g. corn, oats, wheat, rice and barley), potatoes and sprouting cereals (especially in the winter) (Johnsgard 1978, del Hoyo et al. 1992).
Breeding site The nest is a shallow construction of plant matter on the ground amongst vegetation such as grass or dwarf scrub heath, often on raised hummocks or slopes to reduce the risk of flooding and provide a vantage point of the surrounding area (del Hoyo et al. 1992, Kear 2005).
The species is threatened by intense hunting pressure resulting in mortality and disturbance at staging and moulting sites (del Hoyo et al. 1992, Kear 2005, Glahder and Walsh 2006, Nikolaeva et al. 2006). The species is sustainably hunted for sport in Denmark (Bregnballe et al. 2006). It is also susceptible to poisoning by pesticides used on agricultural land (Kwon et al. 2004). Populations in Greenland are threatened by human disturbance at moulting sites from tourists in cruise liners (once displaced from a site birds are unlikely to find unoccupied replacement sites) (Glahder and Walsh 2006), and the species is susceptible to avian influenza so may be threatened by future outbreaks of the vius (Melville and Shortridge 2006). Climatic changes are likely to cause range contractions in this species' already highly restricted breeding range, and are already causing other species (e.g. Canada Geese Branta canadensis) to move northward, increasing competition for resources (Kear 2005, Fox et al. 2006). Oil exploration in the tundra habitat poses a threat to the species' breeding and moulting sites by increasing the possibility of oil spills and chronic oil pollution, by direct habitat destruction (influencing breeding site selection and reducing reproductive success) and through human disturbance (Kear 2005, Glahder and Walsh 2006, Grishanov 2006, Nikolaeva et al. 2006). Wetland habitat degradation due to drainage, peat-extraction and changing management practices (decreased grazing and mowing in meadows leading to scrub over-growth) is also a problem in areas of Russia (Grishanov 2006).
Conservation Actions Underway
EU Birds Directive Annex I, II and III. CMS Appendix II. The following information refers to the species's European range only: Race flavirostris is amongst least numerous subpopulation, but it is increasing, with active protection on its wintering grounds in the U.K. since 1982/1983 (although hunting was only finally banned completely in 2006) (Ely et al. 2020). In 2012 an International Species Action Plan for A. a. flavirostris was published (Stroud et al. 2012).
Conservation Actions Proposed
The following information refers to the species's European range only: The protection of winter roost sites is extremely important for the overall conservation of the species (Ely et al. 2020). Thus key areas should be protected from habitat alteration and disturbance. Strict legislation should be developed and enforced with regards to oil exploration and transportation and the promotion of less intensive farming methods undertaken. Research and monitoring programmes should be maintained and developed to provide data and inform conservation of the species (Stroud et al. 2012).
Text account compilers
Ashpole, J, Butchart, S., Ekstrom, J., Grice, H., Malpas, L., Piggott, A., Rutherford, C.A. & Staneva, A.
BirdLife International (2023) Species factsheet: Anser albifrons. Downloaded from http://www.birdlife.org on 25/03/2023. Recommended citation for factsheets for more than one species: BirdLife International (2023) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 25/03/2023.