Bewick’s swan declines not down to farming changes, study finds
Conservationists are working to research other potential reasons for the 40% fall in numbers of the migratory swans.
Changes to farming practices in the UK are not the cause of a crash in Bewick’s swan numbers, research suggests.
Numbers of the swans, which overwinter in the UK and migrate north to Russia for the summer to breed, fell by nearly 40% between 1995 and 2010, the Wildfowl and Wetlands Trust (WWT) said.
The birds largely feed in farmers’ fields during the winter in the UK, raising concerns that intensification and mechanisation of farming was preventing them getting enough food.
But research by WWT, which compared the body condition of swans it has caught over 50 years to see if a lack of food was the problem, found no evidence “the swans are anything other than well fed” while in the UK.
The study, published in the journal European Journal of Wildlife Research, found no connection between body condition and the recent declines, and the falling numbers were unlikely to be due to food shortages.
The conservation organisation is continuing to work with partners throughout the Bewick’s swans’ migratory range to research all the possible reasons for the declines, including illegal hunting, poisoning, collisions and habitat loss.
Although the British countryside has changed considerably over the last half century, there’s no evidence that the swans are anything other than well fed while they’re here Dr Kevin Wood, WWT
WWT principal research Officer, Dr Kevin Wood, said: “Bewick’s swans have to leave the UK in peak condition to survive their gruelling migration to Russia and arrive ready to breed and rear cygnets during the brief Arctic summer.
“Although the British countryside has changed considerably over the last half century, there’s no evidence that the swans are anything other than well fed while they’re here.
“It’s good news, and we’ve eliminated one line of enquiry, which will allow us to now focus on other issues that might be affecting the swans.
“We’re currently working with researchers across the swans’ range to investigate possible causes of the population decline, which saw numbers fall by almost 40% between 1995 and 2010.
“Hundreds of WWT staff and volunteers have helped to catch and measure swans over the last five decades, so it’s great to be able to use the data to help examine the issues that the Bewick’s swans might face.”