February 8, 2013
Antarctic Adelie Penguins Learn To Cope With Climate Change
[Watch Video: AdÃ©lie Penguins and Climate Change]
Lee Rannals for redOrbit.com — Your Universe Online
Researchers studying AdÃ©lie penguins say that the Antarctic birds are actually coping with climate change, for now.
A team set out with a five-year NSF grant to conduct research on how penguin populations cope with climate change, and on how individual birds cope. During the expedition, they wanted to know why some penguins succeed in coping with climate change, while others do not.
Researchers say that paying close attention to successfully breeding penguins can offer up clues to scientists about how penguins, as a whole, will eventually cope to the changing world.
During the study, the team used GPS and nest tags to note where the AdÃ©lie penguins are, and came back to the spot repeatedly during the season to keep track of their successes and failures.
At this time, the scientists are in their 17th season of research, dealing with 17-year-old penguins.
"So we are getting some idea of the mechanisms of their population regulation, like how breeding success and mortality affect their population growth rates, and how this changes with age and experience," said David Ainley, who has been in the field, working on this research project since 1996.
The AdÃ©lie penguins return from wintering at sea on ice floes, to large bird colonies every year to build nests and breed. The transition from ice floes to bird colonies can be considered risky due to both a harsh environment and predators.
The group of penguins must travel from the colonies into the adjacent ocean to scrummage for food. This type of penguin only exists where there is sea ice, making the ice vitally important to protect their species, and they are highly sensitive to minor changes in the amount of sea ice.
"When the cover on the ocean reaches around 70 percent ice and there's only 30 percent water, conditions become more difficult for AdÃ©lies," said Ainley in a statement. "Above that point penguins begin to have problems with access to the sea and spend too much time walking. Around 20 percent ice cover is ideal for them."
During 2001, an iceberg broke from the Ross Ice Shelf, and the penguin colony at Cape Royds suffered significant losses due to the event.
"Because of the 50 miles of sea ice, the penguins had to walk across to get to open water. The young adults, returning to look for territories, after a short way decided that the walk wasn't worth the effort and began to visit colonies, such as at Cape Bird, closer to seas only partially covered by ice," said Ainley.
He said adults which had nested at Royds started out on the trip, but eventually deserted their mission to get back. After failing to breed for a couple of seasons, he said the adults began to look for new nesting territories.
Every year, the researchers band 400 chicks at the Royds colony, and 1,000 at other, larger colonies. They are able to read the bands using binoculars from 20 feet away. Once the penguins get banded, they will never need to be caught again.
Before the 2001 iceberg had broken off, there were about 4,000 pairs of AdÃ©lies at Cape Royds. However, by 2005, the population had decreased to 2,000 pairs.
"These penguins ignored the rule of thumb that scientists believed for decades--that penguins are faithful to their colony of birth--and they began to emigrate to other colonies, not just as young recruits, but birds that bred previously in their respective colonies. This totally tore up the book on how penguins should relate to their chosen habitat," Ainley said.
Now, the team is trying to determine why some penguins are more successful than others. They found that only 20 percent of the individuals are successful breeders for consecutive years, which they refer to as "super breeders."
According to the researchers, super breeders could hold the key to how the species will adapt to climate change.
"We've been studying the foraging behavior of these super breeders, comparing it to other penguins, and we found that the super breeders are kind of the Michael Phelps of the penguin world. Their foraging trips are shorter, because they dive deeper, dive more rapidly with shorter rest periods at the surface, and ultimately bring back more food to their chicks," Ainley said.
Research equipment helps the team monitor the comings and goings of the birds, and they document how much they weigh when they go out to sea, and how much they weigh upon their return. They apply small instruments to the back of penguins to record their diving behavior, and use satellites to pinpoint where they go to find food.
If all the sea ice were to disappear, then the penguins would not survive. However, subtle changes lead to speculation about how, or if, they are able to adapt.
The research is ongoing, and while the future of sea ice remains uncertain, scientists like Ainley and his team, aim to try and ensure the certainty of these penguins' survival.