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

Now, government experts have confirmed the cause behind this spate of avian deaths, which have hit geese and other wild birds such as ducks and foxes, in addition to swans.

The Animal and Plant Health Agency (APHA) investigated the surge, performing autopsies on the dead birds pulled from the canal. The results showed the birds were in good condition before they died – but had not eaten well before their deaths, suggesting they had suffered poisoning.

The agency says botulism is to blame for the deaths, with specialist tests showing a positive result. Ingestion of the bacteria causes avian botulism and can paralyze birds’ wings, legs and muscles, causing them to suffocate or suffer respiratory failure.

“The bacteria grow in oxygen-free environments and thrive on the proteins in decaying plant and animal material and are often found in lakes, canals and urban reservoirs,” APHA said in a statement to standard.

Unfortunately, there could be more deaths in London’s population of feathered friends to come. “Outbreaks of avian botulism usually involve waterfowl, can last for several weeks and result in hundreds of deaths,” APHA continued. “Outbreaks can recur like once in the environment; the toxin is relatively stable and persistent.’

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

While your instinct might be to help if you find a dead or sick bird on your travels around town, it’s advised not to touch or pick it up. Instead, the public should call the DEFRA helpline on 03459 33 55 77 immediately.

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