| Citation |
BirdLife International. 2019. Anas platyrhynchos (amended version of 2017 assessment). The IUCN Red List of Threatened Species 2019: e.T22680186A155457360. https://dx.doi.org/10.2305/IUCN.UK.2019-3.RLTS.T22680186A155457360.en. Accessed on 17 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 appears to be increasing, hence the species is not thought to 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.
DESCRIPTION
The global population is estimated to number > c.19,000,000 individuals (Wetlands International 2015). The European population is estimated at 2,850,000-4,610,000 pairs, which equates to 5,700,000-9,220,000 mature individuals (BirdLife International 2015).
Trend Justification: The overall population trend is increasing, although some populations may be stable, fluctuating, decreasing, and others have unknown trends (Wetlands International 2015). This species has undergone a large and statistically significant increase over the last 40 years in North America (99.3% increase over 40 years, equating to a 18.8% increase per decade; data from Breeding Bird Survey and/or Christmas Bird Count: [Butcher and Niven 2007]) and in 2015 the speciess abundance was 51% above the long-term average for the period 1955-2014 (Zimpfer et al. 2015). In Europe the population size is estimated to be stable (BirdLife International 2015).
HABITAT AND ECOLOGY
Behaviour In temperate regions breeding populations of this species are sedentary or dispersive, often making local movements during severe weather (Scott and Rose 1996). Other populations are fully migratory (Kear 2005b) with females and juveniles leaving the breeding grounds in the western Palearctic from September and returning as early as February (Kear 2005b). The species breeds between March and June (Madge and Burn 1988) in single pairs or loose groups (del Hoyo et al. 1992) although the exact timing varies with latitude (Madge and Burn 1988). While the females are incubating (Johnsgard 1978) (from mid-May) (Flint et al. 1984, Scott and Rose 1996) the males gather (Madge and Burn 1988) in small flocks and migrate to moulting areas (Flint et al. 1984) where they undergo a flightless moulting period lasting for c.4 weeks (Scott and Rose 1996) (females moult near the breeding grounds) (Flint et al. 1984). Outside of the breeding season the species can be found in small to very large flocks (Madge and Burn 1988) numbering up to several hundreds or even thousands of individuals (Snow and Perrins 1998) especially when moulting (Scott and Rose 1996), on migration (Snow and Perrins 1998) and during the winter (Kear 2005b). The species may also roost both nocturnally and diurnally in communal groups when not breeding (Brown et al. 1982). Habitat The species occurs in almost every wetland type (del Hoyo et al. 1992) although it generally avoids fast-flowing, oligotrophic (del Hoyo et al. 1992, Scott and Rose 1996, Snow and Perrins 1998), deep, exposed, rough, rockbound waters and hard unvegetated areas such as rocky ground, sand dunes and artificial surfacing (Snow and Perrins 1998). It requires water less than 1 m deep for foraging (Snow and Perrins 1998) and shows a preference for freshwater habitats (Madge and Burn 1988) although it may frequent shallow brackish waters as long as they provide the cover (del Hoyo et al. 1992, Scott and Rose 1996) of submerged, floating, emergent or riparian vegetation, dense reedbeds or overhanging branches (Snow and Perrins 1998). Habitats commonly frequented include flooded swampy woodlands, seasonal floodlands (Snow and Perrins 1998), wet grassy swamps and meadows, oxbow lakes (Flint et al. 1984), open waters with mudflats, banks or spits, irrigation networks, reservoirs, ornamental waters (del Hoyo et al. 1992, Scott and Rose 1996, Snow and Perrins 1998), canals and sewage farms (Snow and Perrins 1998). During the winter the species may also be found in saline habitats along the coast (Madge and Burn 1988) where water is shallow, fairly sheltered and within site of land (Snow and Perrins 1998) (e.g. brackish lagoons [Snow and Perrins 1998], brackish estuaries [del Hoyo et al. 1992, Snow and Perrins 1998] and bays [del Hoyo et al. 1992]). Diet The species is omnivorous and opportunistic (del Hoyo et al. 1992, Snow and Perrins 1998), feeding by dabbling in water and by grazing on the land (Snow and Perrins 1998). Its diet consists of seeds and the vegetative parts of aquatic and terrestrial plants (e.g. crops) (del Hoyo et al. 1992), as well as terrestrial and aquatic invertebrates (especially in the spring and summer) such as insects, molluscs, crustaceans, worms and occasionally amphibians and fish (del Hoyo et al. 1992). Breeding site The nest is a shallow depression (Snow and Perrins 1998) or bowl of vegetation that can be situated in many different locations such as within vegetation on the ground, in natural tree cavities (del Hoyo et al. 1992) up to 10 m high (Africa) (Brown et al. 1982), under fallen dead wood, on tree stumps (Flint et al. 1984), under bushes (Brown et al. 1982) and even in abandoned nests of other species (e.g. herons or crows) (Flint et al. 1984). Nests are generally placed close to water (Kear 2005b) although occasionally they may be some distance away (Madge and Burn 1988). Management information "Extensive" grazing of wetland grasslands (c.0.5 cows per hectare) was found to attract a higher abundance of the species in Hungary (Baldi et al. 2005). Studies in Danish coastal wetlands found that the spatial restriction of shore-based shooting was more successful at maintaining waterfowl population sizes than was the temporal restriction of shooting, and therefore that wildfowl reserves should incorporate shooting-free refuges that include adjacent marshland in order to ensure high waterfowl species diversity (Bregnballe et al. 2004). The cyclical removal of adult fish from an artificial waterbody (gravel pit) in the UK resulted in an increase in invertebrate food availability and an increase in the growth of submerged aquatic macrophytes, which in turn led to an increased use of the habitat for brood rearing by the species (Giles 1994). The removed fish (dead or alive) were sold to generate funds (Giles 1994). The species will also nest in artificial nest boxes (Brown et al. 1982, del Hoyo et al. 1992).
THREATS
The species is threatened by wetland habitat degradation and loss from pollution (e.g. petroleum [Grishanov 2006] and pesticide pollution [Kwon et al. 2004]), wetland drainage, 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 reedbeds (Grishanov 2006). The species also suffers mortality as a result of lead shot ingestion (e.g. in Spain [Mateo et al. 1999] and France [Mondain-Monval et al. 2002]) and poisoning from white phosphorous ingestion (from firearms) in Alaska (Steele 1997). It is also susceptible to duck virus enteritis (DVE) (Friend 2006), avian influenza (Melville and Shortridge 2006) and avian botulism (Rocke 2006) so may be threatened by future outbreaks of these diseases (although it may be able to withstand sporadic losses due to its high reproductive potential) (Rocke 2006). The species is predated by American mink Neovison vison in Europe (Opermanis et al. 2001). Utilisation The species is hunted throughout the world (Kear 2005b) mainly for sport (Evans and Day 2002, Bregnballe et al. 2006, Mondain-Monval et al. 2006, Sorrenti et al. 2006), but also for commercial use (food) (Balmaki and Barati 2006). The eggs of this species were (and possibly still are) harvested in Iceland (Gudmundsson 1979).
CONSERVATION ACTIONS
Conservation Actions Underway
CMS Appendix II. EU Birds Directive Annex II and III. The following information refers to the speciess European range only: Extensive grazing of wetland grasslands (c. 0.5 cows per hectare) was found to attract a higher abundance of the species in Hungary (Baldi et al. 2005). Studies in Danish coastal wetlands found that the spatial restriction of shore-based shooting was more successful at maintaining waterfowl population sizes than was the temporal restriction of shooting, and therefore that wildfowl reserves should incorporate shooting-free refuges that include adjacent marshland in order to ensure high waterfowl species diversity (Bregnballe et al. 2004). The cyclical removal of adult fish from an artificial waterbody (gravel pit) in the U.K. resulted in an increase in invertebrate food availability and an increase in the growth of submerged aquatic macrophytes, which in turn led to an increased use of the habitat for brood rearing by the species (Giles 1994). The removed fish (dead or alive) were sold to generate funds (Giles 1994). However, no conservation measures are currently targeted at this species.
Conservation Actions Proposed
The following information refers to the speciess European range only: The species is not threatened and does not require any immediate conservation action but is likely to benefit from conservation measures implemented for other wetland species. |
