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 appears to be increasing, and hence the species does not approach the thresholds for Vulnerable 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 global population is estimated to number c.1,000,000-1,100,000 individuals (Wetlands International 2015). The European population is estimated at 259,000-427,000 pairs, which equates to 519,000-853,000 mature individuals (BirdLife International 2015).
The overall population trend is increasing, although some populations have unknown trends (Wetlands International 2015). In Europe the population trend is estimated to be increasing (BirdLife International 2015).
Behaviour This species is fully migratory although some populations in temperate regions are only sedentary (del Hoyo et al. 1992) or locally dispersive (Scott and Rose 1996), occasionally making irregular movements in very icy winters (del Hoyo et al. 1992). The species breeds from May or April in loose colonies (del Hoyo et al. 1992, Kear 2005a), after which flocks gather to undertake moult migrations to favoured areas (with good feeding opportunities and access to safe roosting sites) (Kear 2005a) to undergo a flightless moulting period lasting c.1 month (Scott and Rose 1996). The species is highly gregarious (Madge and Burn 1988, Kear 2005a) outside of the breeding season (Madge and Burn 1988), with large concentrations forming during the post-breeding moult and before the autumn migration (e.g. flocks of up to 25,000 individuals) (Scott and Rose 1996). The species feeds diurnally, especially during the morning and evening, although non-breeding birds may also feed at night (Kear 2005a). It roosts at night and during the middle of the day on open water (Flint et al. 1984), and may fly to feeding areas more than 10 km away from roosting sites (Kear 2005a) (optimal distance 2-5 km away) (Vickery and Gill 1999). Habitat Breeding During the breeding season the species inhabits wetlands surrounded by fringing vegetation in open grassland (del Hoyo et al. 1992), sedge or heather moorland (Johnsgard 1978), arctic tundra, steppe or semi-desert from sea-level up to 2,300 m (Snow and Perrins 1998). It nests near streams, saltmarshes (Kear 2005a), river flood-plains, reedy marshes, grassy bogs, damp meadows, reed-lined freshwater lakes and estuaries (Johnsgard 1978) close to potential feeding sites such as meadows, grasslands, stubble fields and newly sown cereal fields (Kear 2005a). It requires isolated islands (Kear 2005a) in lakes (Johnsgard 1978) or on along the coast (Kear 2005a) out of reach of land predators for nesting (Kear 2005a). In the autumn (before migration) the species also frequents agricultural land (e.g. sugar-beet, maize and cereal fields) (Kear 2005a). Non-breeding In the winter the species inhabits lowland farmland in open country (Madge and Burn 1988, del Hoyo et al. 1992), swamps (del Hoyo et al. 1992), lakes (Madge and Burn 1988, del Hoyo et al. 1992), reservoirs (Madge and Burn 1988), coastal lagoons (del Hoyo et al. 1992) and estuaries (Madge and Burn 1988). Diet The species is herbivorous, its diet consisting of grass (del Hoyo et al. 1992), the roots, shoots, leaves, stems, seedheads and fruits of other herbaceous marsh vegetation (Johnsgard 1978, del Hoyo et al. 1992), aquatic plants (Johnsgard 1978), and agricultural grain and potatoes (especially in the winter) (del Hoyo et al. 1992). Breeding site The nest is a shallow construction of plant matter (del Hoyo et al. 1992, Snow and Perrins 1998) placed among reedbeds, on the ground (del Hoyo et al. 1992), in or at the base of trees, under bushes or in sheltered hollows on isolated wooded islands on lakes or along coasts (Johnsgard 1978, Kear 2005a), as well as on rafts of vegetation in rivers (Snow and Perrins 1998). Although the species is only semi-colonial, nests may be concentrated within a small area (e.g. placed 11 m apart on small islands) (Johnsgard 1978). Management information On the Vejlerne nature reserve, Denmark, it was found that reedbeds left unharvested for 5-13 years supported the highest nesting densities of this species (Nyeland Kristiansen 1998). Low nesting densities were found in reedbeds in the first four years after reed cutting, and no nests were found in reedbeds cut in the year of study (shoot density may have been too low to provide adequate cover) or in reedbeds left uncut for sixteen years (reed stems may have been too dense) (Nyeland Kristiansen 1998).
This species is threatened by considerable hunting pressures across much of its range (Madge and Burn 1988, del Hoyo et al. 1992) and is susceptible to poisoning from lead shot ingestion (Mateo et al. 1998). It is also persecuted by farmers as it can cause considerable crop damage (Madge and Burn 1988, del Hoyo et al. 1992). The destruction and degradation of wetland habitats due to drainage (Madge and Burn 1988, del Hoyo et al. 1992, Grishanov 2006), conversion to agriculture (Madge and Burn 1988, del Hoyo et al. 1992), petroleum pollution, peat-extraction, changing wetland management practices (e.g. decreased grazing and mowing in meadows leading to scrub over-growth) and the burning and mowing of reeds is also a threat, especially in breeding areas (Grishanov 2006). The species is susceptible to avian influenza so may be threatened by future outbreaks of the virus (Melville and Shortridge 2006).
Conservation Actions Underway
EU Directives Annex II. CMS Appendix II. The following actions refer to the species's European range only: The species has been successfully reintroduced or introduced in some areas, for example Austria, Belgium, parts of Germany, Ireland and the Netherlands (Carboneras and Kirwan 2014).
Conservation Actions Proposed
The following actions refer to the species's European range only: Accurate monitoring of bag numbers in countries where the species is hunted should be implemented. The integration of farming and conservation measures along with protection of key wetland sites is needed to ensure the population remains stable.
Text account compilers
Butchart, S., Ashpole, J, Malpas, L., Ekstrom, J.
BirdLife International (2020) Species factsheet: Anser anser. Downloaded from http://www.birdlife.org on 27/11/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 27/11/2020.