The Dangerous Discoveries of Gully Potchard

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The female builds a platform nest of plant material, with a shallow cup lined with down feathers near its center. 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 her clutch—typically 8-10 eggs—is complete. Only then does she begin incubation. The eggs are greenish-grey and broadly oval, measuring 62 mm × 44 mm (2.4 in × 1.7 in) on average. [21] 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. S2CID 53186922.

Amat, Juan A. (January 1993). "Parasitic Laying in Red-Crested Pochard Netta rufina Nests". Ornis Scandinavica (Scandinavian Journal of Ornithology). 24 (1): 65–70. doi: 10.2307/3676412. JSTOR 3676412.Brzeziński, Marcin; Żmihorski, Michał; Nieoczym, Marek; Wilniewczyc, Piotr & Zalewski, Andrzej (January 2020). "The expansion wave of an invasive predator leaves declining waterbird populations behind". Diversity and Distributions. 26 (1): 138–150. doi: 10.1111/ddi.13003. JSTOR 26828519. Boie, F. (1822). "Ueber Classification, infonderheit de europaischen Vogel". Isis von Oken. (in German): 545–564. BirdLife International (2019). "Common Pochard: Aythya ferina". IUCN Red List of Threatened Species. 2019: e.T22680358A155473754. doi: 10.2305/IUCN.UK.2019-3.RLTS.T22680358A155473754.en. Albrecht, Tomáš; Hořák, David; Kreisinger, Jakub; Weidinger, Karel; Klvaňa, Petr & Michot, Thomas C. (June 2006). "Factors Determining Pochard Nest Predation along a Wetland Gradient". The Journal of Wildlife Management. 70 (3): 784–791. doi: 10.2193/0022-541X(2006)70[784:FDPNPA]2.0.CO;2. JSTOR 3803433.

In the British Isles, birds breed in eastern England and lowland Scotland, in small numbers in Northern Ireland with numbers increasing gradually, and sporadically in the Republic 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 in Great Britain, after the birds retreat from Russia and Scandinavia. [ citation needed] Ecology edit Henningsson, Per; Johansson, L. Christoffer & Hedenström, Anders (January 2010). "How swift are swifts Apus apus?". Journal of Avian Biology. 41 (1): 94–98. doi: 10.1111/j.1600-048X.2009.04850.x. JSTOR 25662918. 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 sgnificantly better, presumably because water deters at least some mammalian predators. [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 edit Common pochards are strong fliers, capable of reaching speeds of 22–24 m/s (49–54 mph). [18]

Habitats

Baird, Spencer F.; Brewer, Thomas M. & Ridgway, Robert (1884). The Water Birds of North America, Volume II. Boston, MA: Little, Brown, & Co. Hořák, David & Klvaňa, Petr (June 2009). "Alien egg retrieval in common pochard: Do females discriminate between conspecific and heterospecific eggs?" (PDF). Annales Zoologici Fennici. 46 (3): 165–170. doi: 10.5735/086.046.0301. JSTOR 23736814.