More eagles are being found gasping for breath, unable to eat, suffering from a lead poisoning that has already killed four of them this year, according to a Delta, B.C.-based non-profit.

Rob Hope of O.W.L. says he’s had 12 eagles brought to him this year with serious poisoning, confirmed with testing equipment. He was able to save eight, but four died in front of him and his staff.

“To see it is pretty brutal,” Hope told CTV News. “The 10-15 minutes before they perish can be pretty hard.”

Hope and staff were so frustrated they decided to take video of the last moments of one of the birds’ life – showing its pain in the hope that people will start paying attention.

In one video, a juvenile eagle’s cry is replaced by a honk; in another, the eagle refuses to eat salmon before vomiting.

The culprit, he believes, could be lead shot that may be used by hunters in the area of Delta and Point Roberts in the United States.

It’s been illegal to use lead shot while hunting migratory birds like ducks for some two decades in B.C. Conservation officers tell CTV News they don’t often see hunters breaking the rules. But it remains legal to use lead to shoot other birds.

Animals that have been wounded by the shot can be eaten by eagles, who ingest the lead. The birds will also scavenge meat left behind by hunters in the wild.

“The lead is stored as calcium, stored in the bones of the animals. They can’t pass it. It builds up and builds up and builds up.”

After seeing the symptoms in around a dozen birds, O.W.L. raised $5,000 for a device to test for lead. The test confirmed that lead was in the birds.

“Ones that did had readings that were off the scale. They had internal organ problems, neurological problems,” he said. “With the machine we were able to confirm that it’s lead and treat the bird accordingly.”

Lead shot is cheaper to buy as well: it was about $17.99 at a local hunting store, compared to $28.99 for the steel equivalent.

“You can buy lead shot at any Canadian Tire. Anyone with a firearms licence can purchase it,” said lawyer Dan Griffith of ATAC Law, which specializes in administrative tribunals including those that regulate firearms use in Canada.

But before governments rush to make lead shot illegal, they should consider the consequences, he said.

“Lead is a relatively safe material to shoot where there are people nearby. It doesn’t travel as far as steel. It’s also more likely to kill an animal rather than wound it. So there are ethical issues as well.”

Rules in Washington State are similar to B.C., though hunters in that state are also required to use “nontoxic” shot for all upland bird hunting and pheasant hunting. There will be a complete ban on using lead ammunition for any hunting throughout California by June 2019.

The issue has been studied by the B.C. Wildlife Federation, which is a conservation group that also trains hunters. Member Victor Skaarup said the agency hasn't seen studies that conclusively prove lead shot is the cause.

“We believe that natural resource decisions should be made on evidence and science,” he said. “We are in the process of doing our due diligence into this issue and potential solutions.

“There have been problems in the past with copper ammunition not being effective in humanely killing game animals. We don’t want to create a bigger problem,” he said.