The regulator said in a post on its website Saturday that Suncor informed them late Friday afternoon of 32 dead waterfowl found at a tailings pond 29 km north of Fort McMurray at Suncor's Base Mine Site.
The post said the energy company found the birds during an oilsands bird-contact monitoring program survey.
It noted that "the state of the wildlife indicates that this may not be a recent event, but this is under review."
The post said Suncor has since advised it's also found a muskrat and a vole, both dead.
The regulator said an AER inspector "was immediately on site" and, in addition to checking bird deterrence systems, the inspector will "ensure mitigation strategies are in place."
"Collaboration between the AER, Suncor, Alberta Environment and Parks, and Environment Canada and Climate Change is underway to ensure that all safety, wildlife, and environmental requirements are met during the response to the incident," the AER post stated.
"We will continue to assess the situation closely and provide further updates as required."
Suncor spokeswoman Erin Rees said in an email the birds were found during one of the company's "regular, required checks." She said appropriate regulatory authorities have been notified.
Alberta Energy Regulator: #Suncor has reported dead #birds at #oilsands tailings pond. #Alberta #FortMcMurray
"At the time of discovery, all bird deterrent systems at Base Plant were active. Our Bird Deterrent Program includes canons, radar and effigies. We have initiated an investigation," Rees said.
Incidents of bird deaths at oilsands tailings ponds over the years include 50 birds that landed at an Imperial Oil tailings area near its Kearl oilsands project in northern Alberta in May 2020. Imperial said at the time it believed it occurred in spite of deterrents because most of the natural water bodies in the area were still frozen.
In January 2019, Syncrude was fined more than $2.7 million after pleading guilty to environmental charges in the deaths of 31 great blue herons at one of its oilsands mines north of Fort McMurray in 2015.
Syncrude was also fined $3 million in 2010 after more than 1,600 ducks died when they landed on a tailings pond in 2008.
Earlier this week, Suncor Energy Inc. reported the release of six million litres of water from a sedimentation pond at its Fort Hills oilsands mine north of Fort McMurray that exceeded guidelines for sediment.
Suncor said it has stopped outflow from the pond and is studying the cause of the problem and how it affected water quality.
Timely notification of water releases from oilsands mines also became an issue earlier this spring.
Last May, Imperial Oil noticed discoloured water seeping from one of its tailings ponds that turned out to be groundwater contaminated by waste, but neither First Nations nor governments were notified about the problem until February after a second release from a catchment pond.
Three inquiries have since been called into that nine-month silence.
This report by The Canadian Press was first published April 22, 2023.