Shocking images of swans on the Hampstead ponds having to chase off a dog which threatened their cygnets have led to calls urging dog walkers to keep their pets under control on the Heath.

On Friday, Heath photographer and member of the Heath and Hampstead's Heath subcommittee Ron Vester caught a rogue dog on camera as it rapidly fled the Hampstead No 2 Pond – pursued by two swans intent on keeping the interloper far away from their cygnets.

Ron said: "You can see the swans teamed up together and ran the dog out of the water. They've had such bad luck this year, losing six of their ten cygnets."

Louisa Green is a swan rescue volunteer and works with the Shepperton Swan Sanctuary.

She said: "Please, please keep your dog on a lead near the Heath's ponds, for the safety of both your pet and the wildlife.

Ham & High: Two parent swans face up to a canine intruder on Hampstead No.2 PondTwo parent swans face up to a canine intruder on Hampstead No.2 Pond (Image: Ron Vester)

"Your pet may be brilliant around children and other pets, but there is no way of knowing how your dog will respond to a 15kg bird trying to protect its young. Unlike geese or ducks, swans do not have vertical flight and need a considerable run-up to become airborne, making it harder for them to escape a loose dog."

Louisa pointed to the dog attack last year which injured a swan on the Highgate chain of ponds, adding: "We desperately do not want to see a repeat of what happened to the famous Highgate pen, Mrs Newbie, when she was taken away from her cygnets and her mate Wallace for three weeks in 2020, for treatment after a serious dog bite to her wing."

Ham & High: Hampstead Heath swan parents try to rescue their cygnet stuck in fishing wireHampstead Heath swan parents try to rescue their cygnet stuck in fishing wire (Image: Ron Vester)

The drama continued a day later when one of the cygnets became entangled in some old fishing wire. After the cygnet's parents tried to free it, it was eventually rescued, with Louisa called in to help disentangle the young swan.

Ron added: "It swam to the shore and Louisa arrived, then the young bird shed the hooks and line and small branches."

He said with the help of Heath ranger Arlene, Louisa was able to catch the cygnet and ensure if was taken to the Swan Sanctuary for treatment even despite the concerned attention of the cob – the male adult swan.

Ham & High: Louisa Green gives the injured cygnet a once-over before taking it to the swan sanctuary, helped by Arlene from the Hampstead Heath rangersLouisa Green gives the injured cygnet a once-over before taking it to the swan sanctuary, helped by Arlene from the Hampstead Heath rangers (Image: Ron Vester)

He said it had been "a very sad year" with only four of the ten cygnets surviving.