Prime Minister Stephen Harper says the federal government will 'get to the bottom' of why hundreds of ducks died at an oilsands plant in northern Alberta this week. (CBC)The federal government will investigate the deaths of about 500 ducks at a northern Alberta oilsands plant, Prime Minister Stephen Harper pledged Thursday.

The birds landed on a pond at a Syncrude oilsands plant north of Fort McMurray. Only five birds were rescued; one has since died, and wildlife rehabilitation workers say it is too early to tell whether the rest will survive.

Harper, who was in Edmonton for the opening of a new heart treatment centre, said he was concerned about what had happened.

"There were supposed to be systems in place to prevent this particular kind of event and obviously we're greatly disappointed, and troubled that we've seen what has occurred here."

Harper promised that officials from Environment Canada would work with their provincial counterparts to "get to the bottom" of the incident.

Harper also said the incident, which has been widely reported, will "no doubt" hurt Canada's reputation.

Incident raises concerns for some in northern Alberta

Some northeast Alberta residents are raising questions about whether oilsands companies are doing enough to protect the environment after about 500 migratory ducks died at a giant toxic waste pond near Fort McMurray.

"To most people, ducks are not important enough to talk about," said Tabitha Pickub, who lives in Fort McMurray.

People in the region trust that the oil companies are following the rules and not polluting the environment, she said, but her confidence has been shaken by the news that Syncrude did not report the duck incident.

One of five ducks rescued from an oilsands tailings pond near Fort McMurray, Alta., and being treated at a wildlife rehabilitation centre outside Edmonton. (CBC)

"Not telling us this, what else are they not telling us?" she asked.

Syncrude officials denied Wednesday there was any attempt to cover up the death of the birds.

Steve Gaudet, who is managing the recovery effort, said his staff were going to alert environment officials once they got the situation under control.

"We wanted to make sure we got on the ground, had a good look without taking weeks. It was just an hour or two to assess the situation."

Alberta Premier Ed Stelmach promised a full investigation Wednesday into the cause of the incident, including whether Syncrude violated provincial regulations by not immediately notifying authorities.

Questions are also being raised about oil companies' environmental practices in Fort Chipewyan, which is on the ducks' migratory route and about 270 kilometres downstream from Fort McMurray along the Athabasca River.

First Nations people in Fort Chipewyan have worried for years about the impact of the upstream oilsands development on the health of their wildlife and water supply.

About 500 ducks landed Monday on the giant tailings pond at a Syncrude-operated oilsands plant north of Fort McMurray. (CBC)

"It was sad because it could have been avoided," Willie Courtoureille, a Cree hunter from Fort Chipewyan, said of the Syncrude duck incident.

The air cannons used by Syncrude and others to scare away birds from the tailing ponds are not very effective, he said. Courtoureille said he wants to see the companies make more intensive efforts like using boats and crews to deter birds from landing on the ponds during periods of high migration.

"Have maybe a month scaring ducks," he suggested. "They've got the money."

Courtoureille said a problem right now is that most of the marshes and wetlands are frozen because of the severe cold weather in the region, making the oilsands ponds particularly attractive to migrating birds at this time of year.

Environmental officials investigating pipeline rupture

The dead ducks are not the only environmental issue emergency officials were dealing with Thursday.

Late Wednesday they were notified of a pipeline rupture that spewed more than a hundred barrels of oil into the Otauwau River near Smith, Alta., about 200 kilometres north of Edmonton.

"Alberta Environment had a spill containment boom brought in.... That boom is there right now to contain and grab whatever oil remains in the water," said David Sheremata, spokesman for the Alberta Energy Resources Conservation Board.

The spill was in a remote area about 40 kilometres west of the town, and it has not affected the drinking supply, Sheremata said.

An investigation into the cause of the spill is underway.

With files from Erik Denison and Patty-Kay Hamilton