The dog walker spotted the female swan on Friday October 29 - and noticed the bird’s leg was trapped in fencing.
The fencing was at the bottom of a steep grassed area at the side of the A64 flyover at Burton Regis nature reserve in Scarborough and approximately eight feet above the nearby railway line.
Animal Rescue Officer Leanne Honess-Heather was called to the scene and could see the only safe way to get to the injured bird would be to climb down the steep banking at the side of the busy road so she called North Yorkshire Fire Service for help.
Two firefighters from Scarborough's Blue Watch used a safety line about to abseil down to the swan, managed to safely free her from the fencing, and took her back up to the top of the embankment.
Leanne was able to check the bird over and could see she had a deep open wound on her leg from trying to free herself from the wire.
She took the injured bird for emergency treatment at nearby Dunslow Road Veterinary Surgery where the wound was cleaned and she was given antibiotics.
The swan is now recuperating with a specialist keeper and she will be released back onto the nature reserve once she has fully recovered.
Leanne said: “I am very grateful to the dog walker who spotted the swan as she was in quite a hidden place and if he had not reported this to us she could have endured a lingering death.
“I knew it would be difficult to safely get to the swan as she was perched high above the railway line but also at the bottom of an embankment at the side of the busy A64.
“I asked the fire service for help and was willing to let them lower me down on ropes to the swan but a firefighter was happy to rescue her.
“We often work with the fire service and are always grateful for their help and they use exercises like this as part of their training.
“I am pleased to say the swan is now doing well and once she is back to full health I will be releasing her back into the wild.”