Photo: The penguin population had been fighting back after years of population decline. (ABC News: Natalie Whiting)
South Australia's already-dwindling little penguin population could be further endangered by a blood-borne parasite, according to an ecologist who has been surveying them.The population on Granite Island at Victor Harbor has been recorded as being in decline since the 1990s.
In 2000, there were about 1,600 penguins on the island. This week, just five breeding pairs were counted.
The little penguins were thought to have been fighting back - with 22 birds recorded in last year's count.
Attacks by predators such as seals and dogs - as well as a higher number of tourists - had been cited as contributing to the long-term drop.
But now another possible cause has emerged - the parasite Plasmodium - which has recently been discovered in South Australia's little penguin colonies.
"[The] birds have a blood parasite - 80 per cent - including Plasmodium," Flinders University penguin ecologist Diane Collombeni-Negrel said.
"We thought 80 per cent was fairly high ... our task now is to figure out ... whether its peculiar to the SA population."
To do that, Dr Collombeni-Negrel said blood samples from birds in other colonies such as Phillip Island would be taken and compared.
She said the Phillip Island colony was growing, describing it as "nice and healthy" with "high numbers".
"If their [Phillip Island] numbers - in terms of parasites - are a lot lower and that's only the South Australian [colony] that have the high number of Plasmodium then we need to worry about it a bit more," Dr Collombeni-Negrel said.
Photo: The little penguins are a big tourist drawcard to Granite Island at Victor Harbor. (ABC News: Natalie Whiting)