CALGARY — A Calgary Zoo investigation was unable to find out what caused the deaths of seven Humboldt penguins last month.
Director of animal care Jamie Dorgan said Thursday it appears something spooked the penguins in the middle of the night, which caused them to suddenly jump into one of two pools in their holding area.
Seven of the zoo's 22 Humboldt penguins were unable to get out safely and a necropsy determined that they died from drowning.
"They're a social species. They tend to all react to things together as a group," said Dorgan.
"Unfortunately we haven't been able to figure out what caused these birds to panic in this case, if that's what happened."
Usually penguins roost quietly throughout the night.
The zoo did detailed interviews with everyone involved and consulted outside experts about what Dornan called a tragic and extraordinary event.
There was camera footage of the penguin building, but none from the holding areas as there are no cameras there, he said. There was no one in the building from 6 p.m. to 6 a.m., he added.
Despite finding no definitive cause for the deaths, the zoo said it is taking steps to make sure something similar doesn't happen again.
It immediately restricted the penguins' access to pools in the back holding areas when staff aren't present and is considering recommendations on how many birds should be kept in the holding areas.
The zoo is also looking into potential physical changes to the pools and is ensuring continuous ambient lighting in the back holding areas at night.
The surviving 15 Humboldt penguins are doing well, said Dorgan.
Humboldts live off the coasts of Chile and Peru, and weigh no more than about six kilograms when fully grown.
The zoo has three other species of penguins including kings, gentoos and rockhoppers.
The zoo has made headlines in the past over the deaths of its animals, including an otter, a giant capybara, a caribou calf and stingrays.
It's upsetting for zoo staff any time animals die suddenly, said Dorgan.
"Our staff spend more than half of their life here looking after these animals and they're really like family members to them.
"It's a really difficult situation."
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