| Citation |
BirdLife International. 2016. Anser albifrons. The IUCN Red List of Threatened Species 2016: e.T22679881A85980652. https://dx.doi.org/10.2305/IUCN.UK.2016-3.RLTS.T22679881A85980652.en. Accessed on 13 March 2022. Brinkman, J.J., van der Ven, W., Allen, D., Hutchinson, R., Jensen, A.E., Perez, C. (2021): Checklist of birds of the Philippines. Wild Bird Club of the Philippines. www.birdwatch.ph |
Description |
JUSTIFICATION
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.
DESCRIPTION
The global population is estimated at 3,100,000-3,200,000 individuals (Wetlands International 2015). The European population is estimated at 259,000-310,000 pairs, which equates to 518,000-620,000 mature individuals (BirdLife International 2015).
Trend Justification: The overall population trend is uncertain, as some populations are decreasing, while others are stable, increasing or have unknown trends (Wetlands International 2015). This species has undergone a large and statistically significant increase over the last 40 years in North America (5500% increase over 40 years, equating to a 173% increase per decade; data from Breeding Bird Survey and/or Christmas Bird Count: Butcher and Niven 2007) Note, however, that these surveys cover less than 50% of the speciess range in North America. In Europe the population size is estimated to be stable (BirdLife International 2015).
HABITAT AND ECOLOGY
Behaviour This species is fully migratory (del Hoyo et al. 1992), travelling in stages via several stop-over sites between separate breeding and wintering grounds (Madge and Burn 1988). The species breeds from late-May or early-June in single pairs or loose groups (del Hoyo et al. 1992), with moulting non-breeders and failed breeders gathering on areas of open water separate from the major breeding congregations (Kear 2005a). After breeding the species gathers in small flocks (less than 30 individuals) (Scott and Rose 1996) to undergo a post-breeding moult period (Madge and Burn 1988) near the breeding grounds where it becomes flightless for c.25 days (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 (Madge and Burn 1988) (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 (Kear 2005a). The species usually forages within 20 km of rooting sites (Kear 2005a), although the optimum distance for foraging areas may be less than this (less than 4 km in Scotland, UK) (Vickery and Gill 1999). Habitat Breeding The species breeds in open (del Hoyo et al. 1992), low-lying, shrubby tundra (Snow and Perrins 1998) on the coast and inland (del Hoyo et al. 1992), in close proximity to marshes, lakes, pools, rivers (del Hoyo et al. 1992, Snow and Perrins 1998), and willow- and shrub-lined ponds and streams (Johnsgard 1978). 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 (del Hoyo et al. 1992) (e.g. improved grassland, stubble fields (Madge and Burn 1988) and wet meadows (Johnsgard 1978)), or in brackish (Kear 2005a) and freshwater marshy habitats (del Hoyo et al. 1992) (such as upland bogs (Madge and Burn 1988), peatlands (Scott and Rose 1996) and floodlands (Kear 2005a)). It may also roost on tidal marshes, in sheltered bays or in estuaries and frequents inland lakes and reservoirs in North America (Kear 2005a). 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 (del Hoyo et al. 1992), as well as agricultural grain (e.g. corn, oats (del Hoyo et al. 1992), wheat, rice and barley (Johnsgard 1978)), potatoes and sprouting cereals (especially in the winter) (del Hoyo et al. 1992). Breeding site The nest is a shallow construction of plant matter on the ground (del Hoyo et al. 1992) 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 (Kear 2005a). Management information An investigation carried out in one of the speciess wintering areas (UK) found that it was most likely to forage on grasslands managed with a livestock (cattle) grazing regime, with a sward height of 13-20 cm, at a distance of less than 9 km away from roosting sites (the optimum distance was 4 km away) (Vickery and Gill 1999). Fertilising the grassland with nitrogen in the autumn (mid-October) at a rate of 125 kg N ha1 was also found to increase the overall species use of the habitat by 42 % compared with unfertilised areas (Vickery and Gill 1999).
THREATS
The species is threatened by intense hunting pressure (del Hoyo et al. 1992) resulting in mortality (Kear 2005a, Nikolaeva et al. 2006) and disturbance at staging (Nikolaeva et al. 2006) and moulting sites (Glahder and Walsh 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 speciess already highly restricted breeding range (Kear 2005a), and are already causing other species (e.g. Canada Geese Branta canadensis) to move northward, increasing competition for resources (Kear 2005a, Fox et al. 2006). Oil exploration in the tundra habitat poses a threat to the speciess breeding (Kear 2005a) and moulting sites (Glahder and Walsh 2006) by increasing the possibility of oil spills and chronic oil pollution (Grishanov 2006, Nikolaeva et al. 2006), by direct habitat destruction (influencing breeding site selection and reducing reproductive success) (Kear 2005a) and through human disturbance (Glahder and Walsh 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). Utilisation The species is sustainably hunted for sport in Denmark (Bregnballe et al. 2006).
CONSERVATION ACTIONS
Conservation Actions Underway
EU Birds Directive Annex I, II and III. CMS Appendix II. The following information refers to the speciess 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) (Carboneras and Kirwan 2013). 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 speciess European range only: The protection of winter roost sites is extremely important for the overall conservation of the species (Carboneras and Kirwan 2013). 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). |
