Scientists at Australia’s Mawson station have begun preliminary investigations into the deaths of Adélie penguins at two island colonies near the station.

Australian Antarctic Division penguin biologist Lyn Irvine discovered a total of 99 dead birds at two colonies during routine field work over the past few days. The total number of birds in the colonies is around 15,000.

There is no outward indication of why the birds died, although it is likely that the deaths are the result of naturally occurring disease.

Immediate steps have been taken to reduce any inadvertent spread of disease as a result of human activity. Precautionary hygiene measures, including restricting access to the penguin colonies and sanitising boots and clothing, have been put in place.

Evidence from long-term monitoring of Adélie penguins at Mawson suggests that the occurrence of dead adult penguins in such numbers is rare and warrants investigation.

Ms Irvine will be undertaking post mortems at Mawson to obtain tissue and blood samples for pathology, to be returned to Australia aboard the Antarctic supply ship Polar Bird, due to arrive in Hobart in late December.

Australian scientists have recently led discussions in Antarctic Treaty forums concerning procedures to minimise risks of people inadvertently introducing disease to Antarctic wildlife or exacerbating naturally occurring diseases.

The current investigation is being undertaken in accordance with protocols for managing such events, developed under the auspices of the Hobart-based Commission for the Conservation of Antarctic Marine Living Resources.