The zoo says Eduardo, a male Humboldt penguin, died Sunday of a fungal infection that affects the respiratory system.
On Monday, Akemi, a three-year-old gentoo penguin, died from heart failure due to avian malaria.
Dr. Doug Whiteside, the zoo's senior veterinarian, says Eduardo failed to respond to treatment that was started when he showed signs of illness on Oct. 5.
As for Akemi, the vet says avian malaria is the second-biggest killer of penguins in captivity.
In August, two Humboldt penguins died, and Whiteside says the cases may be linked.
The zoo says all its penguins are being treated for the fungal infection and tested for avian malaria.
“It seems clear that there may well be an association between Akemi’s death and the two Humboldt deaths in August, as they all shared the outdoor exhibit, and with our wet and then hot summer, were likely exposed to a greater number of mosquitoes carrying the parasite compared to the previous year ” Whiteside said.
“We are still waiting for advanced parasitological tests to come back from a lab in the U.S. for the two Humboldts which would confirm a connection.”
But avian malaria doesn't always show up in blood work in advance and treatment is not always successful in penguins, the vet said.
"Avian malaria is not a threat to humans because mosquitoes carrying malaria and the parasites are species-specific."
Other penguin species at the zoo include kings and rockhoppers.
The zoo was severely affected by flooding that swamped large parts of Calgary and other parts of southern Alberta in June.
Humboldt penguins are native to Chile and Peru. They are named after the cold water current they swim in and which is itself named after geographer, naturalist and explorer Alexander von Humboldt.
The penguins are medium in size and weigh up to six kilograms. They have a black head with a white border that runs from behind the eye, around the ears and chin.
Gentoo penguins are easily recognized by the wide white stripe extending like a bonnet across the top of their head and their bright orange-red bill. They have pale whitish-pink webbed feet and a fairly long tail — the most prominent tail of all penguins
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