Why so many swans die in London

If you’ve walked along the Grand Union Canal in recent weeks, you may have witnessed some worrying sights. A number of swans and other birds have been found dead in the waters, the London stretch of which runs through the north-west of the capital, raising concerns among environmentalists.

Now government specialists have confirmed the cause of this wave of bird deaths, which has affected geese and other wild birds such as ducks and coots in addition to swans.

The Animal and Plant Health Agency (APHA) investigated the wave and carried out post-mortems on dead birds pulled from the canal. The results showed that the birds were in good condition before they died, but had not eaten properly leading up to their death, suggesting that they had suffered poisoning.

The agency says botulism is responsible for the deaths, and specialist tests have returned a positive result. Ingesting bacteria causes avian botulism and can paralyze birds’ wings, legs and muscles, causing them to drown or have breathing problems.

“The bacteria grow in oxygen-deprived environments and thrive on proteins from decaying plant and animal matter, and are commonly found in urban lakes, canals and reservoirs,” APHA said in a statement to The standard.

Sadly, there could be more deaths among London’s population of feathered friends. “Avian botulism outbreaks usually involve waterfowl, can last several weeks and result in hundreds of deaths,” APHA continued. ‘Outbreaks can repeat themselves as once in the environment; the toxin is relatively stable and persistent.’

The rising number of deceased birds found in the Grand Union Canal had raised concerns about bird flu, which has now been ruled out. Most bird botulism in Britain does not affect humans, but the agency has warned that people and their pets should still exercise caution in areas where dead birds are found “as other health risks may be present in these environments”.

Although your instinct may be to help if you find a dead or sick bird during your travels around town, you are advised not to touch or pick it up. Instead, citizens should immediately call the DEFRA helpline on 03459 33 55 77.

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