Syncrude now admits that 1606 birds and waterfowl were killed in one of its tailing ponds, not the original 500 that were reported.
"Once again, I want to apologize for this terribly sad event that happened on our site," says Tom Katinas the company's CEO.
The incident happened in April 2008 when the animals landed on a toxic oilsands tailing pond near Fort McMurray.
On Tuesday, the company said the new number reflects birds that returned to the area in the weeks following the initial deaths.
The company also announced a series of measures aimed at improving its waterfowl protection systems in advance of this year's spring migration period.
The new system includes an enhanced monitoring system and using air cannons well in advance of spring break-up. The new way of doing things is already in operation.
Environmental groups say the changes are positive but do little to address the broader issues of tailings.
"Tailings ponds currently cover 130 square kilometres of area in the Athabasca boreal region and the volume is 720 litres. So we have not only risks to wildlife but risks of seepage," says Jennifer Grant a policy analyst with the Pembina Institute.
Both the federal and provincial governments have laid charges against Syncrude Canada Ltd.
Environment Canada has laid charges against the company for failing to have appropriate deterrents in place at the tailing pond at its Aurora North Site mine facility last spring.
Syncrude is charged with one count under the Migratory Birds Convention Act. The maximum penalty is a fine of $300,000, six months imprisonment, or both.
The province has also laid its own charges under section 155 of the Alberta Environmental Protection and Enchancement Act (EPEA). The maximum penalty is $500,000.