Recent changes in the abundance of Common Pochard Aythya ferina breeding in Europe

National accounts suggest that the Common Pochard Aythya ferina was an uncommon
\nbreeding bird throughout western Europe before 1850. Extensions to the breeding
\nrange in the late 19th century were potentially aided by the rapid development of
\nmanaged fish-ponds in eastern Europe, which provided suitable novel habitat at that
\ntime. Expansion into western Europe followed in subsequent decades. Wetland and
\nwaterbody eutrophication throughout Europe, which likely provided food and cover
\nfor the birds, may have accelerated the rapid expansion from the 1950s until the early
\n1980s. Widespread declines in the last 30 years, especially in eastern Europe, where
\nbreeding numbers are highest, are possibly linked to intensification and/or
\nabandonment of freshwater fish farming and changes in water quality. Studies show
\nthat Pochard gain fitness benefits from nesting in Black-headed Gull Chroicocephalus
\nridibundus colonies and hence has been affected by major losses of European gull
\ncolonies in the last 30 years. The spread of alien fish species such as the Carp Cyprinus
\ncarpio, which compete with Pochard for food resources, is a problem in the
\nMediterranean region. Changing predation pressures (in some cases linked to invasive
\nalien mammals) are also implicated in some areas. Relatively modest numbers breeding
\nin the UK, France and the Netherlands have remained stable or increased over the
\nsame recent span of years, confirming that different factors currently affect Pochard
\nbreeding abundance throughout its range. We urgently need better information
\nrelating to key factors affecting Pochard breeding success and abundance, which is
\ncurrently showing an unfavourable conservation status throughout much of Europe