Granite Island penguins are bolder and more aggressive than those in less disturbed places
In short:
Little penguins on Granite Island are bolder and more aggressive than those living in less disturbed colonies in South Australia.
A Flinders University researcher says there needs to be fewer penguin and human interactions.
What's next?
They are urging people to stay at least 5 metres away from penguin nests at the popular tourist spot as the summer holidays begin.
A Flinders University researcher says the 30 little penguins that nest on Granite Island are bolder than those in other South Australian colonies, and ongoing study of their lives shows the need to limit the impact of tourists.
Diane Colombelli-Negrel said initial research carried out in 2021 compared the behaviour of the penguins living on Granite Island to those at Penneshaw, Emu Bay on Kangaroo Island, and on Troubridge Island, off the coast of southern Yorke Peninsula.
The number of little penguins in the Granite Island colony has dropped from 1,300 to 30 in the past two decades. (Supplied: Flinders University)
"They are definitely bolder on Granite Island, compared to other colonies," Dr Colombelli-Negrel said, noting that the least bold birds on Troubridge Island had very little interaction with humans.
As part of the ongoing research, infra-red camera installed around the island have given researchers a "magnificent insight" to the penguins' lives, showing them as they waddle back to their nests, feed their chicks as well as mate and fight over territory.
Researchers from Flinders University are shocked at how often little penguins on Granite Island are disturbed in their burrows. (Supplied: Arisha Silverlake, Flinders University)
Granite Island is connected by bridge to the seaside holiday town of Victor Harbor, and was home to more than 1,600 adult penguins 20 years ago.
The population today is just 30.
Dr Colombelli-Negrel said the footage from the cameras and ongoing research showed that there was a need to try and reduce the impact of the 800,000 annual visitors to the island on the penguins.
"When humans are around a lot of the penguins can be bolder and more aggressive, in response to nest defence and intrusion," Dr Colombelli-Negrel said.
Chicken and egg situation
Dr Colombelli-Negrel said it was unknown whether the tendency towards bold behaviour was a learned response to the high level of disturbances experienced by the birds on Granite Island.
"It's really like the chicken and the egg," she said.
"Is it because they're bolder that they can handle the stress or is the stress making them bolder?"
Concerns have been raised that the increased boldness in the penguins would make them less invested parents, as had been show in other bird species, but ongoing observations had allayed these fears.
Diane Colombelli-Negrel said little penguins were territorial and monogamous and bred over spring and summer. (Supplied: Diane Colombelli-Negrel)
Measuring boldness
Researchers measure five personality traits in animals: boldness, aggressiveness, exploration, sociality and activity.
To measure the boldness of the little penguins, the team from Flinders University used a short stick to check the burrows.
"We have standard ways of how they respond to that and … some just look at it and then move away and others attack the stick," Dr Colombelli-Negrel said.
She urged visitors to the island over the summer holidays to consider the impact of their presence on the birds.
"Keep your distance so they can come back and return without feeling the stress of our presence," she said.
She said tourists should also avoid using torches around the birds as white light could blind them for several days.