Apparently, they suspect this is the result of chronic respiratory illness, but the timing is a bit odd.

In Kiev zoo killed three penguin

The Administration is confident that the birds killed by an incurable disease.
Alexander Stepanov - 07/09/2010
8Mnogie visitors to the capital's zoo certainly paid attention to the enclosure with the penguins, which is located near the main entrance to the zoo. Now there was only one tenant. Last Saturday, in another world away once three male Humboldt penguins.

The administration of the zoo said that the cause of death of the animals became chronic aspergillosis, ie, the defeat of the upper respiratory tract.

- The disease in birds incurable, - said the press service of the zoo. - Using drugs can only be for some time to improve the health of the animal or bird, but the disease itself sooner or later will still show.

Why one day have died immediately, three eight-year birds, the press service of the Kiev zoo did not say.

Humboldt penguins in captivity live to 30 years and more. In Kiev birds brought seven years ago from a German zoo in the city of Karlsruhe.