FIVE swans have died following an outbreak of a deadly avian disease in the River Weaver.

The RSPCA say they were called to Northwich on Sunday (August 9) following concerns about the welfare of Cygnets in the river. When officers arrived, they sadly found one bird dead at the scene and despite them being able to catch two others, they were later put to sleep after being taken to a vets for treatment.

An RSPCA spokesperson said: "Our officer sadly found one dead cygnet and was able to catch two others and take them to vets where, sadly, they were put to sleep as they were extremely sick.

"We returned to the river following a second call about two adults who were also displaying signs of avian botulism. They were rescued but also very sadly died."

Avian botulism is caused when birds ingest toxins produced by bacteria in the water - the bacteria multiplies in rotting vegetation and is prolific in bodies of water with low oxygen levels and poor water quality. The disease is actually more common in the summer months, because the weather is warmer. Outbreaks in wild birds can result hundreds of deaths.

Birds suffering from botulism may have weakness of paralysis in wings or legs, or may not be able to hold their head up properly - this worsens over days causing them to die from respiratory failure or drowning.

The spokesperson added: "We've asked locals to monitor other birds in the area and to contact us if they see any further sick birds."

If you're concerned about a bird please report it to RSPCA cruelty line on 0300 1234 999. Avian botulism outbreaks should also be reported to local Environmental Health or Defra.