An investigation is underway into why five hundred birds died on the Suffield military base, about 250 km southeast of Calgary.

The birds died after landing in an oil spill. The oil came from a field oil well.

Officials say as much as sixty to ninety barrels of oil leaked from the out of service well site. The well is operated by Calgary-based Harvest Energy Trust.

Crews have now cleaned up the oil.

Contaminated soil has been piled in the area and put under heavy plastic until it can be trucked out.

The oil did not enter any waterways.

Officials with Alberta Energy Resources Conservation Board say a full investigation is underway.

Last April, 500 ducks and other waterfowl died in the oilsands after landing in a tailings pond.