LONDON, ONT -- The staff at Salthaven Wildlife Rehabilitation & Education Centre revealed some sad news over the weekend.

A 15-year-old peregrine falcon named Thunder, who graced the skies of London, was euthanized due to suffering.

Thunder had been rescued by Salthaven staff in late July; she had a fractured wing that made it impossible to fly.

After months of support from Salthaven and frequent visits to the Ontario Veterinary College in Guelph, X-rays revealed that her fractured wing was not healing and it was causing her pain.

Due to her senior age and her inability to fly, Salthaven made the 'heart-wrenching' decision to end her suffering on Sunday morning.

How will the passing of Thunder impact the already at risk species?

"Just more recently in the last 10 to 15 years, peregrine falcons are making a comeback. The peregrine falcon is a species of special concern, but they are moving in the right direction, and Thunder was a part of that,' says Salthaven founder Brian Salt.

Salt says that Thunder alongside her male mate Dundas, were pioneers for establishing the peregrine population in London, a species that is often at risk for pesticide poisoning.

Peregrine falcons are essential for the eco-system, as they eat small rodents and pigeons, two species that would overflow in population without falcons.

Salt says while Thunder has had many hatchlings with Dundas over the years, she is becoming too old to continue the cycle.

"There were no eggs that laid. Any eggs that laid didn’t hatch, with Thunder being out of circulation now, it leaves her old mate open to taking another mate and starting that cycle again. Maybe we'll see more baby falcons up on that TD nest," says Salt.

The feathery friend is being remembered as regal and a beloved addition to the London skyline.

Salt says that Thunder has done her job, and now the best nesting sight in London for falcons is open again to continue her legacy.

"The nesting site is a good one and her mate from last year knows about it. There's a good possibility he will return and mate with a new female," says Salt.