The Alberta Energy Regulator said the animals, waterfowl and songbirds, were found at the Fort Hills oil sands mine jointly own ed by Suncor, Frances Total SA and Canadian mining company Teck Resources Ltd.
Canadas oil sands produce large volumes of byproducts, usually captured in toxic tailings ponds, and associated animal deaths have fueled international concern about the environmental impact of developing the sector.
The provincial regulator said some birds were found dead at one of the northern Alberta sites tailing ponds, while others were found injured and had to be euthanized. The regulator said it was investigating.
It was unclear over what period the birds died. Suncor, the projects majority owner, said they were discovered on Sunday.
Spokeswoman Nicole Fisher said Suncor is concerned about the incident and is doing its own investigation.
We do have a full complement of bird-deterrent systems," she said. "We are engaging with wildlife experts in addition to the regulator to determine if there are additional measures that we can put in place."
Last month, Syncrude Canada, also majority-owned by Suncor, was charged for the deaths of 31 great blue herons found at a sump at the companys Mildred Lake oil sands in 2015.
In 2014, the Alberta regulator cleared several oil sands operators of responsibility for the deaths of 196 waterfowl that landed on their tailings ponds, saying poor weather forced the birds down.