A new report suggests more birds are dying in Alberta's tar sands than the government has let on.

Government industries have estimated that on average, about 65 birds die each year from tailings pond exposure, according to the study released Tuesday. The mean annual rate was determined by analyzing the mortality rate between 2000 and 2007.

However the study, which has been published in September's edition of The Wilson Journal of Ornithology, suggests a number that is at least seven times higher than the industries estimate.

Researchers report that on average, between 458 and 5,029 birds die each year at the Bitumen Tailings Pond in northeastern Alberta.

In fact, researchers say that average is likely conservative because the data that was studied doesn't include bird deaths that occurred before spring, between spring and fall migration and after fall migration.

Researchers say the wide range is due to spatial and temporal variations in bird mortality rates.

Tailings ponds are said to contain bitumen, polycyclic aromatic hydrocarbons, volatile organic compounds, naphthenic acids, brine, heavy metals, and ammonia.

The study concludes by saying the government needs to introduce a system that is "statistically valid" and is standardized.

"Systematic monitoring and accurate, timely reporting would provide data useful to all those concerned with bird conservation and management in the tar sands region," the study says.

Dr. Kevin Timoney, a scientist with Treeline Ecological Research, said the industries' estimates are hampering efforts to protect wildlife in the tar sands.

"The ad hoc monitoring by industry, sanctioned by government, cannot address pressing questions whose answers would aid in the conservation of both migratory and resident birds," said Timoney, a co-author of the study.

Greenpeace Canada expressed outrage at the finding of the study and released a statement asking for an "independent scientific analysis."

"We can no longer let the fox guard the hen house," Mike Hudema, Greenpeace climate and energy campaigner, was quoted as saying. "It has become glaringly obvious that we can't trust the government to give us accurate information on the tar sands industry.

"It's time for independent scientific analysis so that the public knows the full scope of this horrific industry and can make a decision about the kind of future we want to invest in: a toxic legacy or a green economy we can all live and breathe in?"

The study also found:

• Landing deterrent systems at tailings ponds are only partially effective and don't always prevent bird deaths.
• Researchers are unable to determine the fate of lightly oiled birds that continue on the migration path.
• There is not enough data on deaths reported during extreme weather or how often there are circumstances leading to massive bird deaths.

The Alberta government stated that oilsands companies must have monitoring and deterrence mechanisms in operation for all animals.

However, Alberta Sustainable Resource Development Minister Mel Knight admitted that more needs to be done.

"I would not argue at all with the study with respect to the fact that there could be better work done on monitoring, and we're going to work to do that," he said. "At the end of the day we'll come to appreciate the advice that is being given to us and we'll use it."