A bald eagle nicknamed Birdzilla is now spending her days floating across tree tops, but little more than a month ago she was so sick she could hardly lift her head or wings.

The 6.4-kilogram bird is the largest eagle to have ever visited the Cobequid Wildlife Rehabilitation Centre in Brookfield, N.S. She was brought in Dec. 28 after provincial conservation officers were alerted to a sick eagle in Pictou County.

"We had seven eagles at our place when we had her … but she made the other ones look like mini-birds," said Helene Van Doninck, veterinarian and director of the wildlife centre.

The raptor arrived showing symptoms of lead poisoning. She was weak, unable to walk, stand or fly.

"They usually look like they're drunk or stoned," said Van Doninck.

The number of lead-poisoned birds that arrive at the centre varies from year to year. But Van Doninck said it's estimated 25 per cent of eagles brought to rehab centres in North American have serious lead poisoning.

She said one of the most common sources of lead is ammunition. Eagles ingest it when they feast on what remains of an animal that's been shot.

'We've never had a bird so weak'

Just a small fragment of lead from a bullet or lead shot is enough to kill an eagle. Birdzilla had been on the ground for some time, according to the rehab centre. She was dehydrated, cold and full of lice.

The team went to work on the eagle, warming the bird under a heat lamp and performing X-rays to see whether any large pieces of lead needed removal. Birdzilla was so weak she didn't need to be anesthetized.

"We just laid her on the X-ray table, just put her on her back, set up the X-ray and took the shot and she didn't move," Van Dininck said. "We've never had a bird so weak."

Once the presence of lead was confirmed in a blood sample, the centre started treating the bird with a chemical that binds to lead and takes it out of tissue. The kidneys then filter it out and the bird excretes the toxin.

'She was flying like a jet fighter'

After nearly a month at the centre, Van Doninck and her team released Birdzilla back into the wild Saturday.

"She got strong, gradually, and we knew with her being such a big, robust female this time of year … this time of year is important for them, defending their territory, nest building, getting ready for the upcoming mating season — so we made the call," said Van Doninck.

"The weather was good, she was flying like a fighter jet in our enclosure so we decided that Saturday was a good day to let her go."

Van Doninck tours the Maritimes, talking to anglers and hunters about the harm of using lead products. She also occasionally heads up an ammo and lead tackle exchange for hunters and anglers.

The Department of Natural Resources no longer uses lead ammunition, and the Nova Scotia Federation of Anglers and Hunters encourages its members to switch to non-lead ammunition and tackle.

Van Doninck said she's had a lot of luck with people like Clifford Paul, who ran the Cape Breton moose harvest.

"He's been a huge advocate and that's great because that gets the word around to the community."