Australia’s little penguins aren’t as well-known as the koala or the kangaroo, but they are cute enough to go head-to-head with these icons of the outback. In recent years, scientists have grown concerned about the world’s tiniest penguin as their populations have steadily declined. Now, a new report suggests that rapid changes in the ocean’s temperature may be partly to blame as the warmer waters make the little penguin’s preferred prey more scarce.
The little penguin, also known as the “fairy penguin,” is the world’s smallest penguin, weighing roughly two pounds and standing less than a foot tall. Found in southern Australia and New Zealand, the little penguins feed mainly off of small fish and ocean-going creatures, like sardines, anchovies, and krill. Normally, the little penguin’s prey thrives off of nutrients and plankton stirred up by the East Australian Current each spring, but in recent years these waters have grown warmer, driving away the temperature-sensitive little fish and leaving the little penguins struggling to find food, Devin Powell reports for National Geographic.
“We’re seeing that warm years are quite bad for the penguins, and it’s not hard to see that if the temperature keeps going up, things might get worse,” Carroll tells Powell.
While scientists aren’t sure why the East Australian Current is heating up, it’s happening fast. Overall, the current’s temperature has risen about 2 degrees Fahrenheit since the 1950s, which suggests that it could be a result of climate change, Emily DeMarco writes for SFGate. Yet, the powerful annual current is warming two- to three-times faster as the ocean’s surface, according to Carroll.
That might be enough to change the migration patterns of the penguins’ prey—influencing when the little fish show up in the area and how long they stick around.
“It’s really important that we understand what might happen to these ecosystems as these systems change,” Carroll tells DeMarco.
To figure out how the little penguins were coping with the changes in their environment, DeMarco and her colleagues monitored little penguins as they hunted over the course of three breeding seasons from 2012 to 2014. The researchers strapped GPS trackers to the tiny penguins backs along with accelerometers, devices that measured their body movements (and the reason your smartphone knows that you’ve turned it on its side), which let them know when their subjects were just swimming around or when they were on the hunt, Powell writes.
The movement data showed that the penguins often avoided warmer waters, where they might find more fish. And during years when the water was warmer overall, the penguins ended up catching less fish altogether.
While some predators adjust their own hunting patterns to match their prey’s, the little penguins are too small to travel very far. During breeding seasons, the penguins only travel up to 15 miles a day, making it difficult to find new hunting grounds, DeMarco writes.
Vanishing prey isn’t the little penguin’s only problem: the penguins are also a favorite food for animals like seals, foxes, cats and dogs. But with oceanic temperatures in eastern Australia projected to rise up to nine degrees Fahrenheit by the end of the century, the penguins may be left hungry with increasing frequency.
“I wouldn't say which factor [threatening penguins] is the most important,” conservation biologist Dee Boersma, who wasn't involved in the study, tells Powell. “But climate change is going to be a big problem for penguins.”