Common Pochard Aythya ferina Scientific name definitions

42–49 cm (1 Snow, D. W., and C. M. Perrins, Editors (1998). The Birds of the Western Palearctic. Concise Edition. Volume 1. Non-passerines. Oxford University Press, Oxford, UK. Close ); male 585–1240 g, female 467–1090 g (2 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ); wingspan 72–82 cm (1 Snow, D. W., and C. M. Perrins, Editors (1998). The Birds of the Western Palearctic. Concise Edition. Volume 1. Non-passerines. Oxford University Press, Oxford, UK. Close ). Breeding male  has rufous-chestnut head  , blackish breast, upper mantle, undertail-coverts, rump and tail, body  grey with vermiculations  , becoming darker on upperwing-coverts, paler and more uniform silver-grey on flight feathers, with darker tips to primaries and secondaries, and almost white underwing  ; bill usually dark grey with black nail and broad, pale grey subterminal band; legs and feet bluish grey, and bright orange-red eyes  . Female-like eclipse plumage, but always has greyer body than latter, more contrasting dark breast and no well-defined facial pattern. Female has dull brown head with pale grey eyestripe, throat, lores and cheeks (pattern very variable), greyish-brown body  , becoming darker above, wings as male but overall browner; bill dull grey to blackish, with broad black tip and broad, pale grey subterminal band, and eyes warm brown. Very similar to allopatric A. americana but head shape different: male has red iris (yellow in A. americana) and slightly different pattern on bill ; female has different bill colour and whiter flanks than A. americana. Male A. valisineria is larger and overall paler than male of present species, and has blackish wash to head, flatter forehead and much longer, all-dark bill, although note that some of present species can have an all-blackish bill (like A. valisineria) or a narrow, pale, subterminal band and black tip (as in A. americana (3 Madge, S. (1991). Separation of Canvasback and Redhead from Pochard. Birding World. 4(12): 365-368. Close ) and some A. fuligula × A. ferina hybrids) (4 Kemp, J. (1991). Hybrid Pochards resembling Redheads. Birding World. 4(12): 353. Close ). Care is also required when faced with potential vagrants of any of these species in also eliminating potential hybrids, which are comparatively frequent (5 Reeber, S. (2002). Problèmes d’identification posés par les hybrides de fuligules Aythya sp. en Europe de l’Ouest. Ornithos 9(5):177–209. Close ). Juvenile resembles adult female but has more mottled underparts, duller head lacking eyestripe, has pale grey or white vermiculations on some body feathers, and mantle, breast and flanks are dark grey; appears to take more than one year to achieve full adult plumage; young female distinguished from male by having uniform grey-brown mantle, scapulars and tertials with olive fringes, brown-grey wing-coverts and unflecked white tips to secondaries (2 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ).

• Mallard x Common Pochard (hybrid) Anas platyrhynchos x Aythya ferina
• Red-crested x Common Pochard (hybrid) Netta rufina x Aythya ferina
• Common Pochard x Ferruginous Duck (hybrid) Aythya ferina x nyroca
• Common x Baer's Pochard (hybrid) Aythya ferina x baeri
• Common Pochard x Tufted Duck (hybrid) Aythya ferina x fuligula

Breeds in W Europe E through C Asia (in band at 40–60° N) to SC Siberia and N China to 120° E. Winters S to N & E Africa, India and S & E Asia.

Well-vegetated eutropic to neutral swamps, marshes, lakes and slow-flowing rivers with areas of open water and abundant emergent fringing vegetation (2 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ), but also breeds on saline, brackish and soda lakes, occasionally even in sheltered coastal bays (2 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). In winter, often on larger lakes, reservoirs, fishponds, mineral extraction pits, brackish coastal lagoons and tidal estuaries, but ranging from oliogotrophic upland waterbodies to lowland eutrophic lakes (2 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Recorded to 2690 m in Ethiopia in winter (7 Ash, J. S., and J. Atkins (2009). Birds of Ethiopia and Eritrea: An Atlas of Distribution. Christopher Helm, London, UK. Close ).

Partially migratory, but some individuals may migrate very long distances, with up to 1000 km sometimes covered in just 2–3 days (8 Hofer, J., Korner-Nievergelt, F., Korner-Nievergelt, P., Kestenholz, M. and Jenni, L. (2006). Herkunft und Zugverhalten von in der Schweiz überwinternden oder durchziehenden Tafelenten Aythya ferina [Origin and migration pattern of Common Pochards Aythya ferina wintering in Switzerland]. Orn. Beob.. 103(2): 65-86. Close ), thus although most British-ringed birds originate from Baltic states, Russia, Germany and Finland, there are recoveries during the breeding season as far as 150º E; neverthless, most far eastern breeders doubtless winter in SE & E Asia (2 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Birds ringed or recovered in Switzerland have been recovered (or ringed) in S France, C & E Europe and E to lowland W Siberia, and during the breeding season recoveries concentrate in the Russian-Kazakh steppe, while in winter movements regularly occur between Switzerland and the Po Valley, to S France and in a NW direction (8 Hofer, J., Korner-Nievergelt, F., Korner-Nievergelt, P., Kestenholz, M. and Jenni, L. (2006). Herkunft und Zugverhalten von in der Schweiz überwinternden oder durchziehenden Tafelenten Aythya ferina [Origin and migration pattern of Common Pochards Aythya ferina wintering in Switzerland]. Orn. Beob.. 103(2): 65-86. Close ). Breeders in Denmark, Fennoscandia, N Germany, Poland, Baltic states and Russia between 50º N and 60º N (E to 70º E) move W & SW to W Europe (as far as Ireland) and S to NW Africa, while those wintering in E Mediterranean and Black Sea originate from even further E (1 Snow, D. W., and C. M. Perrins, Editors (1998). The Birds of the Western Palearctic. Concise Edition. Volume 1. Non-passerines. Oxford University Press, Oxford, UK. Close ). Males generally depart the breeding areas first (by c. 2 weeks), moving through E & S Europe in late Sept and Oct, and W Europe in Oct–Nov, and females perhaps on average moving further as males quickly populate first suitable waterbodies, while return passage (which has advanced among males by 20 days since 1970s) (8 Hofer, J., Korner-Nievergelt, F., Korner-Nievergelt, P., Kestenholz, M. and Jenni, L. (2006). Herkunft und Zugverhalten von in der Schweiz überwinternden oder durchziehenden Tafelenten Aythya ferina [Origin and migration pattern of Common Pochards Aythya ferina wintering in Switzerland]. Orn. Beob.. 103(2): 65-86. Close ) commences as early as Feb (if weather mild), although most birds leave winter grounds in Mar and early Apr, with males again departing first (1 Snow, D. W., and C. M. Perrins, Editors (1998). The Birds of the Western Palearctic. Concise Edition. Volume 1. Non-passerines. Oxford University Press, Oxford, UK. Close , 8 Hofer, J., Korner-Nievergelt, F., Korner-Nievergelt, P., Kestenholz, M. and Jenni, L. (2006). Herkunft und Zugverhalten von in der Schweiz überwinternden oder durchziehenden Tafelenten Aythya ferina [Origin and migration pattern of Common Pochards Aythya ferina wintering in Switzerland]. Orn. Beob.. 103(2): 65-86. Close ). However, in Ethiopia, present overall between late Oct and early Apr, with occasional records from early May and early Jul (7 Ash, J. S., and J. Atkins (2009). Birds of Ethiopia and Eritrea: An Atlas of Distribution. Christopher Helm, London, UK. Close ), whereas in N Kenya the species has been seen in Dec–Mar (9 Pearson, D. J., and B. S. Meadows (1992). Numbers, distribution and seasonality of Palaearctic duck in Kenya. Scopus 15:109–119. Close ). Present throughout year in temperate regions (e.g. C & NW Europe), where within-winter movements in France can be > 100 km (typically to ice-free areas) (10 Gourlay-Larour, M.-L., Schricke, V., Sorin, C., L’Hostis, M. and Caizergues, A. (2012). Movements of wintering diving ducks: new insights from nasal saddled individuals. Bird Study. 59(3): 266–278. Close ), but some populations winter in sub-Saharan Africa (exceptionally S to Tanzania, Congo (11 Dowsett-Lemaire, F., and R. J. Dowsett (1998). Further additions to and deletions from the avifauna of Congo-Brazzaville. Malimbus 20(1):15–32. Close , 12 Demey, R., P. Herroelen, and T. Pedersen (2000). Additions and annotations to the avifauna of Congo-Kinshasa (ex-Zaïre). Bulletin of the British Ornithologists' Club 120(3):154–172. Close ), Cameroon, Nigeria (13 Akinsola, O.A., Ezealor, A.U. and Polet, G. (2000). Conservation of waterbirds in the Hadejia-Nguru WetIands, Nigeria: current efforts and problems. Ostrich. 71(1–2): 118–121. Close , 14 Polet, G. (2000). Waterfowl and flood extent in the Hadejia-Nguru wetlands of north-east Nigeria. Bird Conservation International. 10(3): 203–209. Close ), Ghana (15 Dowsett-Lemaire, F., and R. J. Dowsett (2014). The Birds of Ghana: An Atlas and Handbook. Tauraco Press, Liège, Belgium. Close ) and Gambia) (2 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ), Middle East , SW USSR, Indian Subcontinent, SE Asia and Japan . Vagrant to Faeroes, Azores, Canary and Cape Verde Is; also to Philippines, Mariana Is (Guam and Saipan) (16 Stinson, D.W., Wiles, G.J. and Reichel, J.D. (1997). Migrant land birds and water birds in the Mariana Islands. Pacific Sci. 51(3): 314–327. Close ), Hawaii, Pribilof Is, the W & C Aleutians and mainland Alaska (17 Howell, S. N. G., I. Lewington, and W. Russell (2014). Rare Birds of North America. Princeton University Press, Princeton, NJ, USA. Close ), once in Saskatchewan (Jun 1977) (18 Patten, M.A. (1993). First record of the Common Pochard in California. Western Birds. 24(4): 235-240. Close ), in California (Feb 1989, Jan–Feb 1991, Jan–Feb and Nov 1992, Dec 1994) and Quebec (May 2008) (17 Howell, S. N. G., I. Lewington, and W. Russell (2014). Rare Birds of North America. Princeton University Press, Princeton, NJ, USA. Close ).

Seeds, roots and green parts of grasses, sedges and aquatic plants (especially Chara, but also Potamogeton, Myriophyllum and Ceratophyllum) (2 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ); also small invertebrates (aquatic insects and their larvae, molluscs, crustaceans, worms), amphibians and small fish; bread (19 Zonfrillo, B. (2009). Goosanders taking bread. British Birds 102(9):509–510. Close ) and potatoes recorded in some parts of range (20 Kemp, J. B. (1992). Wildfowl eating potatoes. British Birds 85(9):495. Close ). Perhaps some seasonal or sex-/age-related variation in diet, with females and ducklings apparently reliant on chironomid and caddisfly larvae in summer, and these food sources are also particularly important at sites lacking macrophytes and in other seasons (21 Phillips, V.E. (1991). Pochard Aythya ferina use of chironomid-rich feeding habitat in winter. Bird Study. 38(2): 118-122. Close , 2 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Feeds by diving (usually at depths of 1–2·5 m) (1 Snow, D. W., and C. M. Perrins, Editors (1998). The Birds of the Western Palearctic. Concise Edition. Volume 1. Non-passerines. Oxford University Press, Oxford, UK. Close ), upending or dabbling on surface, and also filters mud on shore, but some differences in techniques between males and females, with males apparently deeper divers and dominant in agonistic encounters, sometimes displacing females from food-rich sites (22 Marsden, S.J. and Sullivan, M.S. (2000). Intersexual differences in feeding ecology in a male-dominated wintering Pochard Aythya ferina population. Ardea. 88(1): 1-7. Close , 2 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Sometimes associated with sewage outfalls in winter, where abundant Tubifex and other species taken (2 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ), and also observed directly associating with, and benefiting from, foraging Cygnus columbianus bewickii, but without kleptoparasitizing the swans (23 Gyimesi, A., van Lith, B. and Nolet, B.A. (2012). Commensal foraging with Bewick’s Swans Cygnus bewickii doubles instantaneous intake rate of Common Pochards Aythya ferina. Ardea. 100(1): 55-62. Close ). Frequently crepuscular and may also feed throughout the night, especially in winter (2 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Gathers into large flocks, especially during post-breeding moult, when groups of up to 50,000 males can be common in W Europe and Russia (2 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ).

Vocalizations generally considered weak, low-pitched and inaudible at any distance (1 Snow, D. W., and C. M. Perrins, Editors (1998). The Birds of the Western Palearctic. Concise Edition. Volume 1. Non-passerines. Oxford University Press, Oxford, UK. Close ). Males are generally silent, but utter wheezy whistles in display  , e.g. nasal “wiwierr” and louder, single, double-noted or tripled “kil-kil-kil” that descend in pitch (1 Snow, D. W., and C. M. Perrins, Editors (1998). The Birds of the Western Palearctic. Concise Edition. Volume 1. Non-passerines. Oxford University Press, Oxford, UK. Close ), while female gives soft growl when flushed and various other, mainly monosyllabic, rasping or explosive calls (1 Snow, D. W., and C. M. Perrins, Editors (1998). The Birds of the Western Palearctic. Concise Edition. Volume 1. Non-passerines. Oxford University Press, Oxford, UK. Close ); contact calls of ducklings comprise groups of 2–4 notes, and their distress calls are higher-pitched and faster than those of Anas ducks of same age and size (2 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ).

Starts Apr/May, especially latter but depending on region, with breeding grounds in Siberia not usually reached before early May (1 Snow, D. W., and C. M. Perrins, Editors (1998). The Birds of the Western Palearctic. Concise Edition. Volume 1. Non-passerines. Oxford University Press, Oxford, UK. Close ); in S Spain, broods observed 22 May to 15 Jun in one study (24 Green, A. J., J. D. Navarro, J. C. Dolz, and J. Aragoneses (1999). Timing of brood emergence in a duck community in Mediterranean Spain. Bird Study 46(1):116–118. Close ) and the season appears similar in East Anglia (SE England) (25 Bloomfield, A. (2012). Hatching season for Common Pochards. British Birds. 105(8): 479. Close ). Probably seasonally monogamous, with pair-bond typically surviving until first or second week of incubation, although some males will accompany their broods; pair-bonds usually form in winter, although others not until spring (1 Snow, D. W., and C. M. Perrins, Editors (1998). The Birds of the Western Palearctic. Concise Edition. Volume 1. Non-passerines. Oxford University Press, Oxford, UK. Close ). In single pairs or loose groups, sometimes in association with Black-headed Gulls (Larus ridibundus), which apparently offer some measure of protection against predators (26 Väänänen, V.-M. (2000). Predation risk associated with nesting in gull colonies by two Aythya species: observations and an experimental test. Journal of Avian Biology. 31(1): 31–35. Close ), for example, Hooded Crow (Corvus cornix), Common Raven (C. corax) and American mink (Mustela vison) (27 Opermanis, O., Mednis, A. and Bauga, I. (2001). Duck nests and predators: interaction, specialisation and possible management. Wildl. Biol.. 7: 87–96. Close ); nest is shallow depression in thick heap of grass, reed stems and leaves, lined with down, on ground or over water, concealed in thick vegetation, usually < 10 m from water (2 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ); in Czech Republic, 77% of 380 nests over water, 16% on islets (elsewhere including man-made ones) (28 Burgess, N. D., and G. J. M. Hirons (1992). Creation and management of artificial nesting sites for wetland birds. Journal of Environmental Management 34(4):285–295. Close ) and the other 7% on dry ground (2 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Generally single-brooded, although up to 45% of birds that lost their first clutches attempted replacements in one study (2 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Clutch 8–10 green-grey eggs (range 3–22, with clutch sizes declining later in season, although nests containing > 15 eggs probably result of parasitism), size 56–68 mm × 39–47 mm, mass 55–74 g (2 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ); incubation c. 25 (24–28) (2 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ) days; chicks have brown down on upperparts , and yellow on underparts, face and dorsal spots, becoming white on ventral region, weigh 37·2 on hatching (in captivity) (2 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ); fledging 50–55 days, deserted by female at onset of wing moult, and some young may leave own brood to join other female even when very small (1 Snow, D. W., and C. M. Perrins, Editors (1998). The Birds of the Western Palearctic. Concise Edition. Volume 1. Non-passerines. Oxford University Press, Oxford, UK. Close ). Intra- and interspecific parasitism common (up to 89% in one study) (29 Šťovíček, O., Kreisinger, J., Javůrková, V. and Albrecht, T. (2013). High rates of conspecific brood parasitism revealed by microsatellite analysis in a diving duck, the common pochard Aythya ferina. Journal of Avian Biology. 44(4): 369-375. Close ) and moderate levels of egg dumping appear to have little or no effect on success of host (30 Dugger, B.D. and Blums, P. (2001). Effect of conspecific brood parasitism on host fitness for Tufted Duck and Common Pochard. Auk. 118(3): 717–726. Close ), with Netta rufina parasitizing this species in Spain (2 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ), and A. fuligula and Anas platyrhynchos have been recorded dumping eggs in nests of A. ferina in the Czech Republic (29 Šťovíček, O., Kreisinger, J., Javůrková, V. and Albrecht, T. (2013). High rates of conspecific brood parasitism revealed by microsatellite analysis in a diving duck, the common pochard Aythya ferina. Journal of Avian Biology. 44(4): 369-375. Close ), while both A. ferina and Netta rufina may simultaneously parasitize Anas platyrhynchos in the same country (31 Amat, J. A. (1991). Effects of Red-crested Pochard nest parasitism on Mallards. Wilson Bulletin 103(3):501–503. Close ). In study of breeding success on Czech fishponds, 66% of females nested successfully, 18% unsuccessfully and remainder did not attempt to breed, with large inter-annual differences reflecting climatic conditions, especially drought, when < 33% of birds attempted to breed (2 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ); water levels also proved to be strong determinant of whether birds decided to breed or not in Swedish study (32 Söderholm, S. (2005). Populationsutveckling och häckningsframgång för brunand Aythya ferina vid Angarnsjöängen, Uppland, 1995–22392395 [Population development and breeding success of Pochard Aythya ferina at Angarnsjöängen, Uppland, in 1995–22392395]. Ornis Svecica. 15: 220-228. Close ). Mean brood size on hatching 7·1 (six in replacement clutches) (2 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). During a Latvian study, yearling females initiated nests later than older birds, while clutch size and brood size declined seasonally, but there was an age-specific increase in breeding performance between one and two years of age such that brood size and duckling mass of yearling females were smaller than those of older females, thus even inexperienced two year olds nested earlier and produced larger broods and ducklings than younger females (33 Blums, P., Hepp, G.R. and Mednis, A. (1997). Age-specific reproduction in three species of European ducks. Auk. 114(4): 737–747. Close ); also found that site fidelity was positively related to breeding success and that fidelity is higher for older females than young birds (34 Blums, P., Nichols, J.D., Hines, J.E. and Mednis, A. (2002). Sources of variation in survival and breeding site fidelity in three species of European ducks. Journal of Animal Ecology. 71: 438–450. Close ), while duckling survival and recruitment declined with advancing hatch date (35 Blums, P., Clark, R.G. and Mednis, A. (2002). Patterns of reproductive effort and success in birds: path analyses of long-term data from European ducks. Journal of Animal Ecology. 71: 280–295. Close ). Same Latvian study found that natal dispersal among marked birds averaged 629 m ± 39 m (range 0–10·6 km) and was much smaller for breeders at 239 m ± 16 m (range 0–9·2 km) (36 Blums, P., Nichols, J.D., Hines, J.E., Lindberg, M.S. and Mednis, A. (2003). Estimating natal dispersal movement rates of female European ducks with multistate modelling. Journal of Animal Ecology. 72: 1027–1042. Close ). Success of 4·42 young reared to fledging per successful pair, and of 1·83 per pair (all pairs) in one study in Germany; hatching success of 56% found in Czechoslovakia. Sexual maturity at c. 1, occasionally c. 2, years, with a 20-year-old captive bird remaining fertile throughout (2 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ) and no evidence of senescence in wild population (37 Nichols, J.D., Hines, J.E. and Blums, P. (1997). Tests for senescent decline in annual survival probabilities of Common Pochards, Aythya ferina. Ecology. 78(4): 1009-1018. Close ). Annual adult survival was 65% during a Latvian study (34 Blums, P., Nichols, J.D., Hines, J.E. and Mednis, A. (2002). Sources of variation in survival and breeding site fidelity in three species of European ducks. Journal of Animal Ecology. 71: 438–450. Close ). Longevity record held by British-ringed bird that was recovered when 22 years old (2 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ).

VULNERABLE. Abundant, with a global population estimated to number 1,950,000–2,250,000 individuals (38 Wetlands International (2015). Waterbird Population Estimates. Wetlands International, Wageningen, The Netherlands. Close ). Westwards spread registered during 19th century when colonized Sweden, Finland, Denmark and the Netherlands, followed by Britain (although some evidence species was breeding there from at least 1840s (39 Fox, A.D. (1991). History of the Pochard breeding in Britain. British Birds. 84(3): 83-98. Close ) and where still more numerous in S than N) (40 Holling, M., and The Rare Breeding Birds Panel (2011). Rare breeding birds in the United Kingdom in 2009. British Birds 104(9):476–537. Close ), much of C Europe and France in early 20th century, finally Germany, Belgium (1956) and Spain, this expansion apparently the result of drying of C Asian breeding areas, and facilitated by increasing availability of suitable man-made wetlands and specially provided breeding sites (28 Burgess, N. D., and G. J. M. Hirons (1992). Creation and management of artificial nesting sites for wetland birds. Journal of Environmental Management 34(4):285–295. Close ), as well as the species’ ability to take advantage of new feeding opportunities (2 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). First bred in Italy in 1952, Greece (1953, on Crete), Iceland in 1954, Norway in 1972, Morocco in 1977 and Portugal in 1995 (1 Snow, D. W., and C. M. Perrins, Editors (1998). The Birds of the Western Palearctic. Concise Edition. Volume 1. Non-passerines. Oxford University Press, Oxford, UK. Close ). European breeding population estimated at 198,000–285,000 pairs (41 BirdLife International (2015). European Red List of Birds. Office for Official Publications of the European Communities, Luxembourg. Close ); largest breeding populations are in European Russia (90,000–120,000 pairs in 2008–2011), Poland (20,000–30,000 pairs in 1992–2004), Ukraine (17,300–25,900 pairs in 2000), Finland (10,000–16,000 pairs in 2006–2012) and Czech Republic (9,000–17,000 pairs in 2012) (41 BirdLife International (2015). European Red List of Birds. Office for Official Publications of the European Communities, Luxembourg. Close ). Wintering population in W Palearctic c. 1,600,000 birds, where now common throughout W Europe (this subpopulation numbers c. 350,000 individuals), and C Europe is a particularly important wintering area, including as a refuge for birds from NW Europe during severe weather there (which has been known to lead to starvation of large numbers of present species) (42 Suter, W. and van Eerden, M.R. (1992). Simultaneous mass starvation of wintering diving ducks in Switzerland and the Netherlands: a wrong decision in the right strategy? Ardea. 80(2): 229–242. Close , 2 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Important numbers also in Asia: over 100,000 winter in Japan; c. 30,000–40,000 in Iran; partial counts in winter 1991 yielded 22,000 in Kazakhstan, 96,300 in Azerbaijan (where up to 75,000 were recorded at Gyzylagach State Reserve in winter in late 1990s) (43 Sultanov, E. (2008). Recent waterbird counts in Gyzylagach, the Azerbaijan Republic’s most important Ramsar site, with comments on conservation. Podoces. 3(1–2): 31–38. Close ), 72,784 in Turkmenistan, 124,694 in Pakistan and 36,212 in India . SW Asian population most recently (late 1990s) estimated at 350,000 birds (trends unknown), with a further 100,000–1,000,000 in S Asia, and perhaps 600,000–1,000,000 in SE & E Asia in 1990s, of which c. 500,000 in China, 30,000 in South Korea and 170,000 in Japan (2 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ) (although numbers there have been in decline since) (44 Kasahara, S. and Koyama, K. (2010). Population trends of common wintering waterfowl in Japan: participatory monitoring data from 1996 to 211106111069. Orn. Sci.. 9(1): 23–36. Close , 45 Kasahara, S. and Koyama, K. (2011). [Regional population trend of common wintering waterfowl in Japan, from 1996 to 286869]. Jap. J. Orn.. 60(1): 35–51. (In Japanese with English summary.). Close ). Wintering population in W Mediterranean has decreased by up to 70% in recent decades, although at least some of these birds have doubtless relocated elsewhere, and signs of decline also evident in E Mediterranean, Black Sea and Sea of Azov regions, which areas together may harbour up to 1,000,000 birds in winter (2 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Numbers wintering in the UK have declined c. 50% within the 25 years prior to winter 2010/11 (46 Pitches, A. (2012). News & Comment: Mixed fortunes for wintering waterbirds. British Birds. 105(11): 692–693. Close ) (and the most recent estimates of breeding numbers also indicate a decline there (47 Holling, M., and The Rare Breeding Birds Panel (2013). Rare breeding birds in the United Kingdom in 2011. British Birds 106(9):496–554. Close ), but NW European population as a whole appears to be stable and numbers wintering in the Baltic have decreased only slightly in the last two decades (48 Skov, H., S. Heinänen, R. Žydelis, J. Bellebaum, S. Bzoma, M. Dagys, J. Durinck, S. Garthe, G. Grishanov, M. Hario, J. J. Kieckbusch, J. Kube, A. Kuresoo, K. Larsson, L. Luigujoe, W. Meissner, H. W. Nehls, L. Nilsson, I. K. Petersen, M. M. Roos, S. Pihl, N. Sonntag, A. Stock, A. Stipniece, and A. Wahl (2011). Waterbird Populations and Pressures in the Baltic Sea. TemaNord 2011:550. Nordic Council of Ministers, Copenhagen, Denmark. Close ). Overall European breeding population estimated to be decreasing by 30–49% over three generations (22·8 years) (41 BirdLife International (2015). European Red List of Birds. Office for Official Publications of the European Communities, Luxembourg. Close ), with European winter population following a similar trend. Since Europe holds 35% of global population (40% in winter), such declines are globally significant BirdLife International (2015) Species factsheet: Aythya ferina. Downloaded from http://www.birdlife.org on 19/11/2015. . Furthermore, some Asian populations (in Bangladesh, Japan and South Korea) are reported to be decreasing BirdLife International (2015) Species factsheet: Aythya ferina. Downloaded from http://www.birdlife.org on 19/11/2015. . Declines probably due to excessive hunting and habitat destruction and change, with eutrophication an important factor in loss of some suitable habitat; this process promotes development of phytoplankton-dominated wetlands, with opaque rather than clear water, leading to decline in bottom flora, especially Chara, on which this species is so dependent (2 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). On other hand, species has benefited from waste discharge outfalls from food-processing plants, which provide suitable feeding opportunities (2 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Sensitive to disturbance during breeding season (2 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Not regarded as a species of conservation concern until 2015, when information suggesting that the population has declined rapidly across the majority of its range caused the species to be classified as Vulnerable.