[Regulator75]

http://www.cbc.ca/news/canada/calgar...ults-1.3942842

Despite an "exhaustive investigation," the Calgary Zoo says it still doesn't know why seven penguins drowned last month.

Seven Humboldt penguins were found dead at the back of the Penguin Plunge exhibit at the Calgary Zoo on Dec. 8. The animals drowned in a back holding area of the popular Penguin Plunge exhibit.

In a release issued Thursday morning, the zoo said there is "no conclusive evidence" as to what led to the drownings.