Wikipedia

Common pochard

Thecommon pochard[2](/ˈpɒtʃərd/;Aythya ferina), known simply aspochardin the United Kingdom, is a medium-sizeddiving duckin the familyAnatidae.It is widespread across thePalearctic.It breeds primarily in thestepperegions ofScandinaviaandSiberia,and winters further south and west.

Common pochard
Male
Female
Scientific classificationEdit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Anseriformes
Family: Anatidae
Genus: Aythya
Species:
A. ferina
Binomial name
Aythya ferina
Range ofA. ferina
Breeding
Resident
Non-breeding
Synonyms

Anas ferinaLinnaeus, 1758
Anas rufaGmelin 1788
Fuligula ferina(Linnaeus, 1758)
Nyroca ferina(Linnaeus, 1758)

Taxonomy and systematics

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Swedish taxonomistCarl Linnaeusfirst assigned ascientific nameto the common pochard in the tenth edition of his landmark treatiseSystema Naturae;this was the first edition which included such names. He called the duckAnas ferina.[3]In 1822, German zoologistFriedrich Boiecreated the genusAythyafor variousdiving ducks,and moved the common pochard to that new genus.[4]Uptake ofAythyaas the genus for the common pochard was mixed for much of the next century, with some authors leaving the duck in the genusAnasor assigning it to various other now-defunct genera instead.[5]The common pochard is considered asuperspecieswith thecanvasback.[6]In the past, theredheadof North America was thought to be a subspecies,[5]but the common pochard is now agreed to bemonotypic,with no subspecies.[2]It is known to havehybridisedwithtufted duckandferruginous duckin captivity, and these known combinations resemble suspected hybrids seen in the wild, which may share the same parentage.[7]Hybridisations with thered-crested pochardhave also been reported.[8]

The genus nameAythyais derived from theAncient Greekwordaithuia,an unidentifiedseabirdmentioned by authors includingHesychiusandAristotle.[9]Thespecies nameis theLatinwordferina,meaning "wild game" (derived fromferus,meaning "wild" ).[10]The common name "pochard" was first applied to the duck in the mid-1500s; its origin and etymology is unknown.[11]It is also sometimes known asEuropean pochard,Eurasian pochard,or (particularly in the UK) simplypochard.[12]

Description

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The common pochard is a plump, medium-sizeddiving duck,measuring 42–49 cm (17–19 in) in length, with a wingspan of 72–82 cm (28–32 in).[13][14][15]It is stocky and short-tailed, with a sloping forehead and relatively longbill.Its weight (which has been reported only for winter birds) ranges from 467 to 1,240 g (16.5 to 43.7 oz). Males average larger and heavier than females.[14]Like most ducks, it issexually dimorphic.[16]

The male has a chestnut-coloured head and neck, a black breast and tail, and a pale grey body, marked with finevermiculations.Hisbillis dark grey, with a wide blue-grey band across the middle. Hisirisis yellow-orange to red, growing brighter in the breeding season.[15]

The legs and feet are grey in both sexes and all ages. The female's iris is brown, sometimes tending towards yellowish-brown. The juvenile's iris is yellow-olive, but attains its adult colour during the first winter.[16]

Voice

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Songs and calls
Listen to the common pochard on xeno-canto

The male is generally silent, though he may whistle softly as part of his courtship display. The female growls softly—a sound transcribed askrrr—if she is flushed.[16]The duckling has a short contact call of two to four notes. If distressed, its calls are higher and faster than are those ofAnasducklings of the same size and age.[14]

Similar species

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The male common pochard is quite similar to the male canvasback, but the latter has an all-dark bill. It is also similar to the redhead, but the latter has a yellow iris and a greyer back.[14]

Distribution and habitat

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Their breeding habitat consists ofmarshesand lakes with a metre or more water depth. Pochards breed in much of temperate and northernEuropeand across thePalearctic.They aremigratory,and spend winter in the south and west of Europe.[17]

In theBritish Isles,birds breed in easternEnglandand lowlandScotland,in small numbers inNorthern Irelandwith numbers increasing gradually, and sporadically in theRepublic of Ireland,where it may also be increasing. While uncommon, individuals are also occasionally seen in the south of England, and small populations are sometimes observed on the River Thames. Large numbers stay overwinter inGreat Britain,after the birds retreat fromRussiaandScandinavia.[17]

Ecology

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These are gregarious birds; they form large flocks in winter, often mixing with other species of diving duck.[16]They are strong fliers; in direct, flapping flight, they can reach speeds of 22–24 m/s (49–54 mph).[18]

Food and feeding

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Common pochards feed on plant material (including seeds), small fish,molluscs,and otheraquatic invertebrates.[13][19]They feed primarily by diving to retrieve items from under the water's surface; however, they will also upend and dabble at items on the water's surface. They do most of their feeding at night.

They regularly forage in close association withBewick'sandwhooper swans,two species that trample underwater sediment to excavate food. Studies have shown that this behaviour greatly increases the food intake rate of the pochards, as they glean food items that drift away from where the swans are trampling. This rate can be double what it would be if the birds were feeding on their own.[20]

Breeding

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Eggs from the collection of theMuseum of Toulouse

The female builds aplatform nestof plant material, with a shallow cup lined withdown feathersnear its centre. This is placed either on the ground within 10 m (33 ft) of the water's edge or in the water with the platform rising above the water's surface. It is always located in dense cover. The female lays one egg daily until herclutch—typically 8-10eggs—is complete. Only then does she beginincubation.The eggs are greenish-grey and broadly oval, measuring 62 mm × 44 mm (2.4 in × 1.7 in) on average. They are incubated by the female and hatch synchronously after around 25 days. When off the nest the female will cover the eggs with down. The young areprecocial,nidifugousand can feed themselves. They fledge when aged 50–55 days.[21]

Like many ducks, common pochards suffer a high rate of parasitic egg-laying, a behaviour also known as egg dumping. Studies have shown that as many as 89% of nests in some areas contain one or more eggs not laid by the incubating female.[22][23]The percentage of parasitic eggs may reach as high as 37% of all eggs laid in some populations.[23]There appears to be little cost to the incubating female for accepting eggs that are not her own, and indeed she will roll any egg left close to her nest into her clutch.[24][25]However, if the number of parasitic eggs exceeds six, she is twice as likely to abandon her nest.[26]Females sometimes lay their eggs in the nests of other duck species as well; red-crested pochards are unwitting hosts in some areas.[27]

Levels of nest predation can be high, particularly for nests located in upland areas. Those located on islands, or over water (on artificial platforms) do significantly better, presumably because water deters at least somemammalianpredators.[28]Nesting success depends on a number of factors, including the age of the female, her body mass, the date the nest was started, and the size of the clutch. Older, heavier birds are more successful than younger, lighter ones. Smaller, earlier-laid clutches are less likely to be abandoned than larger, later ones.[29]

Conservation and threats

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Common pochards are strong fliers, capable of reaching speeds of 22–24 m/s (49–54 mph).[18]

The common pochard is one of the species protected by theAgreement on the Conservation of African-Eurasian Migratory Waterbirds(AEWA).[30]TheInternational Union for Conservation of Naturerates the species asvulnerable.Though it has a huge range and an extremely large population, there is evidence of precipitous declines in several regions. These reach somewhere in the range of 30–49 per cent over a 23-year period in Europe, for example.[1]In number of countries, its population is decreasing mainly due to the urbanization and transformation of the natural habitats, as well as due to overhunting.[31]Introduced predators, such as theAmerican mink,have wreaked havoc on some populations. In Poland, for example, one studied population showed a 92 per cent decrease in the 30 years after mink first became established in the area.[32]Birds, includingcarrion crowsandmarsh harriersare important nest predators.[33]

A further threat to conservation efforts of this bird is that 75 official languages are spoken across the countries in which it is found, thus scientific knowledge is scattered across those different languages, and collaboration on conservation efforts is more difficult.[34]

It is the host for a variety of internal parasites, includingcestodes,nematodesandtrematodes.These includeParamonostomum aythyae,a trematode which was first isolated from the common pochard; it is carried in the gut.[35]In some locations, the common pochard may be an important vector of avianschistosomes,which are harboured in the bird's nasal andmesentericblood vessels. These schistosomes can be transmitted to humans who work or swim in the same wetland areas as the ducks, potentially causingcercarial dermatitis.[36]Known blood parasites includeHaemoproteus greineri,Haemoproteus nettionisandPlasmodium circumflexum.[37]It is also known to carryToxoplasma gondii.[38]

Notes

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  1. ^abBirdLife International 2019.
  2. ^abGill, Donsker & Rasmussen 2021.
  3. ^Linnaeus 1758,p. 126.
  4. ^Boie 1822,p. 564.
  5. ^abBaird, Brewer & Ridgway 1884,p. 28.
  6. ^Carboneras 1992,p. 616.
  7. ^Madge & Burn 1988,p. 244.
  8. ^Randler 2008,p. 144.
  9. ^Jobling 2010,p. 64.
  10. ^Jobling 2010,p. 158.
  11. ^Lexico 2021.
  12. ^Madge & Burn 1988,p. 246.
  13. ^abThe Wildlife Trusts 2021.
  14. ^abcdKear 2005,p. 652.
  15. ^abCramp 1977,p. 561.
  16. ^abcdMadge & Burn 1988,p. 247.
  17. ^abMadge & Burn 1988,p. 248.
  18. ^abHenningsson, Johansson & Hedenström 2010,p. 94.
  19. ^RSPB 2021.
  20. ^Gyimesi, van Lith & Nolet 2012.
  21. ^Cramp 1977,p. 567.
  22. ^Št́ovíček et al. 2013,p. 369.
  23. ^abPetrzelkova et al. 2013,p. 103.
  24. ^Dugger & Blums 2001,p. 717.
  25. ^Hořák & Klvaňa 2009.
  26. ^Dugger & Blums 2001,p. 721.
  27. ^Amat 1993,p. 65.
  28. ^Albrecht et al. 2006,p. 788.
  29. ^Blums, Mednis & Clark 1997,p. 919.
  30. ^AEWA 2018,p. 21.
  31. ^Common Pochard (Aythya ferina) in Armenia.2017. In online publication: "The State of Breeding Birds of Armenia". TSE NGO, Armenian Bird Census Council. Retrieved on 10 October 2017.
  32. ^Brzeziński et al. 2020,p. 144.
  33. ^Albrecht et al. 2006,p. 789.
  34. ^Negret, Pablo Jose; Atkinson, Scott C.; Woodworth, Bradley K.; Corella Tor, Marina; Allan, James R.; Fuller, Richard A.; Amano, Tatsuya (20 April 2022)."Language barriers in global bird conservation".PLOS One.17(4): e0267151.doi:10.1371/JOURNAL.PONE.0267151.ISSN1932-6203.PMC9020734.PMID35442973.Wikidata Q112271116.
  35. ^Thebo et al. 2019,p. 151–152.
  36. ^Athari, Gohar-Dehi & Rostami-Jalilian 2006,p. 13–14.
  37. ^Elahi et al. 2014.
  38. ^Mancianti et al. 2013,p. 561.

References

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Further reading

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  • Carbone, C.; Houston, A.I. (August 1994). "Patterns in the diving behaviour of the pochard, Aythya ferina: a test of an optimality model".Animal Behaviour.48(2): 457–465.doi:10.1006/anbe.1994.1259.S2CID53186922.
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