The number of common pochards migrating to the UK has decreased by 60 per cent since the 1980s.
This decrease is mirrored by declines in breeding numbers elsewhere in Europe.
“Waterbirds live complex lives,” said Dr Eileen Rees from the Wildfowl and Wetlands Trust, “and their wetland habitats are entwined with our own need for food and water.”
Researchers have found that the decline is related to gulls, mink and nutrients.
Pochards build their nests among black-headed gull colonies for protection and there are fewer black-headed gull nesting colonies across a number of European countries, including Norway, Germany and Latvia.
Explosions of plants and algaes in wetlands and waterways, caused by nutrients washing off farmland, has prevent ed pochards and other birds from diving for food.
The American mink has become a major wetland predator. The species was originally introduced and farmed in Europe for its fur, but escaped and is now considered to be an invasive species in many countries.
Despite the decline in migrating pochards, the number of them breeding in the UK has actually increased and the latest estimate is 653 pairs.
Find out more in the latest issue of Wildfowl.
Read more wildlife news stories in BBC Wildlife Magazine