North Yorkshire Police has confirmed it is investigating the incident after the breeding female was discovered suffering from a gunshot injury in a garden near the village of Thorpe Basset in Ryedale.
The stricken bird of prey was found on Easter Saturday.
Jean Thorpe, who runs Ryedale Wildlife Rehabilitation from her home in nearby Norton, was contacted to see if she could nurse the creature back to health.
“When the family found her, she was unable to stand and it was initially feared that she may have been caught up in a fence,” Mrs Thorpe said.
As a Raptor Rescue-approved expert who cares for hundreds of sick and injured birds and animals each year, Mrs Thorpe said she could tell that the owl had been attempting to breed because it had what is known as a brood patch in her feathers - a pronounced bare patch of skin where she had been sitting on her eggs to incubate them.
She explained: “I examined the bird and could see its legs were injured but couldn’t find any wounds.”
After feeding the owl and allowing it to rest in a warm box in a quiet shed, Mrs Thorpe took it to the Battle Flatts Veterinary Practice at Stamford Bridge for further examination by vet Mark Naguib.
An x-ray was performed which revealed the full extent of her injuries. It highlighted a mushroom-shaped air rifle pellet that had broken both of her legs.
Mrs Thorpe said it was likely that the owl’s injuries dated back to late-March, despite the fact that the creature was not found until April 5.
“By the time the bird was found, the fractures were actually healing so we think the injuries were already ten to 14 days old,” she said.
“We think this bird had managed to get back to her nest and continue brooding her eggs. The legs had started to heal in this sitting position. Her mate must have continued to feed her. The bond between a mated pair of Tawnies is very strong and constant.”
But the owl’s prognosis was that it would never be able to hunt for itself again, and so the decision was made to put down the injured owl.
Mrs Thorpe said: “The callous shooter not only illegally cut short her life, but also that of her coming brood.
“We’re hoping that someone may know who did this.”
PC Jeremy Walmsley, a wildlife crime officer based at Malton police station, is investigating the attack on the owl. Anyone with information about the incident, should contact PC Walmsley by calling 101.