The sea ice around a massive Adelie penguin colony in Antarctica has melted early this year, according to a group of New Zealand scientists based there.
Cape Bird on the Antarctic peninsula is home to 30,000 breeding pairs of Adelie penguins, who rely on the sea ice to gather krill and ice fish for their chicks. Without it, some are being forced to travel much further for food, leaving their chicks hungry for days.
Landcare Research Ecologist Dean Anderson is one of three people stationed on site for the summer to watch the breeding season, in a study of a new fishing sanctuary that has been set up in the Ross Sea.
He says the sea ice broke out around two weeks ago, which is unusual.
“The adults are spending more time out at sea, and less frequent trips back to the chicks, which has reduced provisioning rates and we’re seeing a slight plateau in the growth rates of chicks,” he says.
“We’re following individual nests over the season and trying to get detailed information about movement and provisioning rates and how those chicks then fare.”
Mr Anderson’s study is focused on the Ross Sea Marine Protected (MPA) area, an international fishing sanctuary recently set up in the ocean off Antarctica. It is now the world’s biggest MPA, stretching across 1.55 million square kilometers.
Adelies make the perfect research subject they are highly reliant on the sea for survival and changes in their fishing grounds can have a big impact on their health.
To carry out the study, they’ve fenced 96 breeding pairs on the colony. They microchipped 25 pairs which are weighed as the empty and leave the fence through an electronic gate.
Research assistant Susanne Anderson says it tells them how successful the birds have been at foraging.
“The weight going in will show us how much they’ve been eating at sea, because they’ll be bringing in a big stomach full of krill, which they will then feed to their chicks,” she says.
The scientists say it’s too early to know why the sea has melted so early this year, but say it could be a natural event or a result of climate change.
Field technician Brian Karl has spent 26 years at Cape Bird over the years in different studies and says the sea ice usually doesn’t melt until the end of January, which the chicks are bigger.
“It’s unusual for it to be as extensive as this so early in the season and for it to be open like this for so long,” he says.
“They’ll be bringing back less food and less frequently for the chicks, and the chicks will be quite hungry, and that makes them more vulnerable to skua.”
The real impact will be known once they have collected the data, with the first stage of the study wrapping up in two weeks.