Alberta's energy regulator said on Saturday it is investigating reports that about 30 blue herons have died at a Syncrude Canada oil sands mine site in the northern part of the Canadian province.
The Alberta Energy Regulator said it sent investigators to the Syncrude Canada Mildred Lake site, which is about 40 km (25 miles) north of Fort McMurray.
In 2010, Syncrude was fined C$3 million ($2.29 million) for negligence in the 2008 deaths of 1,600 ducks in a toxic waste pond, a case that fueled international concern about the environmental impact of developing Canada's oil sands.
Syncrude's partners include Canadian Oil Sands Ltd, Imperial Oil Ltd, Suncor Energy Inc, Sinopec , CNOOC Ltd's Nexen, Japan's Mocal Energy and Murphy Oil Co.
Officials with Syncrude did not immediately respond to a request for comment.
In November, the Alberta regulator cleared several oil sands operators of responsibility for the death of 196 waterfowl that landed on their toxic tailings ponds, saying poor weather conditions forced the birds down.
($1 = 1.3128 Canadian dollars)
(Reporting by Jeffrey Hodgson)