Federal officials are investigating whether the deaths of 500 ducks at a northern Alberta oilsands plant could be part of a more widespread problem following the discovery of another oil-coated duck — this time farther along the birds' migration route.

The discovery comes as Syncrude Canada, the oil company that owned the waste-filled tailings pond where the ducks were found, has acknowledged that more birds landed on the site but flew away.

"When we got our boats on the water on Tuesday our first effort was to scare those birds away," Syncrude Canada spokesman Alain Moore told CBC News.

A native hunter discovered this oil-covered mallard in Wood Buffalo Park, about 250 kilometres from the Syncrude tailings pond. (Parks Canada)

Moore said company staff have no idea if those ducks had become coated in oil.

About 500 ducks landed Monday on the tailings pond filled with waste from Syncrude's oilsands operation at the Aurora North Site mine, north of Fort McMurray.

Only five birds were rescued; three have since died, and wildlife rehabilitation workers say it is too early to tell whether the other two will survive.

On Tuesday evening, native hunter Roland Campbell discovered an oil-coated duck in Wood Buffalo Park, about 250 kilometres away from the tailings pond.

Campbell said he was shocked when he went to prepare a duck for his dinner.

"I assumed it was mud when I first killed it, it was covered in oil," he said.

"I took a better look at this duck and that's when I noticed he was all full of tar on his stomach and feet."

Hunter Roland Campbell, who found the oil-covered duck in Wood Buffalo Park, is seen here cleaning an uncontaminated duck from a recent hunting trip. (Erik Denison/CBC)

Campbell gave the duck to Environment Canada's office in Fort Chipewyan. Federal park rangers are out searching for other contaminated birds in the area.

The oil on the bird will be tested and compared with samples taken from the tailings pond belonging to Syncrude Canada.

Bird expert Ruth Kleinbub said the discovery of another oil-coated duck makes it likely that more are out there.

"I don't think it's the only bird that got oil on it and was able to fly some distance," Kleinbub said. "How many are out there dying a slow death?"

Kleinbub said oil degrades a duck's feathers, causing them to lose their insulation value. She said it's only a matter of days before the bird can die from hypothermia.

With files from Erik Denison