The Calgary Zoo has announced that two of its penguins died over the long-weekend.

A Humboldt penguin named Eduardo died on Sunday of Aspergillosis, a respiratory infection, after he failed to respond to treatment.

The three-and-a-half-year-old male penguin showed signs of illness on October 5 and was receiving therapy.

 “The post-mortem examination showed advanced and severe infection to his left air sacs and left lung, while his right side was normal,” explained Dr. Doug Whiteside, Senior Staff Veterinarian. “Owing to a bird’s very efficient respiratory system and also because animals are so adept at hiding that they are not feeling well, unfortunately by the time Eduardo demonstrated signs of illness, his disease was far too advanced for treatment to be effective.”

The zoo says it is proactively treating all of its penguins for Aspergillus.

On Monday October 14, a three-year-old Gentoo penguin named Akemi also died.

Akemi died from heart failure due to avian malaria.

The zoo says the two diseases are unrelated but commonly affect penguins and other birds.

“One week ago Akemi’s blood showed no evidence of malaria, however the parasite was detected in the red blood cells yesterday,” explained Dr. Whiteside. “Like the two Humboldt penguins we lost in August, Akemi became ill suddenly and died within a very short period of time - less than 48 hours. However, she is the first penguin where we have been able to demonstrate the parasite in red blood cells.”

Zoo keepers are testing the entire outdoor flock 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 mosquitos carrying the parasite compared to Penguins - 2 the previous year ” said Whiteside. “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.”

The zoo says avian malaria does not always show up in blood work in advance and that the available preventative treatment is not always successful in penguins.