(KSL) Since Dec. 1, 13 bald eagles have died in Utah, and no one knows why.

"All the birds that have been brought in have varying degrees of paralysis, weakness in the wings and legs, and then very quickly moving in to having tremors then full blown seizures," said DaLyn Erickson, Wildlife Rehabilitation Center of Northern Utah. "Once the seizures start, that's pretty much it."

Eight bald eagles have been brought into her Ogden clinic in the past three weeks, and five of them have died.

"Typically, we'll get 3 bald eagles a year," Erickson said. "We're concerned just because it's something new. It's something we don't know. We have yet to ever see this quantity of birds coming in of one species in this short amount of time."

The birds have been found throughout northern and central Utah in Box Elder, Weber, Davis, Tooele, and Utah counties.

Tests for lead, possibly from shotgun shells in other birds the eagles ate, have come back negative.

"We just don't know. We hope to have more information next week. Some more of the results should be coming in at that point, so we should know more then. But right now we just don't know what's going on," Erickson said.

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