Climate change is hurting penguins unevenly in Antarctica

Adelie penguins have endured hard times in the western Antarctic Peninsula, where global warming has warmed faster than almost anywhere else on the planet. This and other factors have led to a sharp decline in Adele’s population in recent decades.

But on the east side, it’s a different story.

“It’s just a complete train wreck on the west side of the peninsula,” said Heather J. Lynch, a statistical ecologist at Stony Brook University who studies penguin populations and how they change. “But on the east side, the populations are stable and quite healthy.”

Dr. Lynch uses satellite imagery in much of his work, however also organized expeditions to explore penguins to the peninsula, the northernmost part of the Antarctic continent. At the last one, in January, three of her current and former doctoral students conducted a census of islands on the eastern side of the Wedel Peninsula.

Their work has shown that Adele’s population there has changed little from previous censuses in the last two decades. This suggests that as global warming continues and Adele’s populations decline in other parts of the continent, Wedel could remain an important refuge for birds.

“This is a good confirmation that where the climate has not changed so dramatically, populations have not changed dramatically,” said Dr Lynch.

The Weddell Sea is known as icy, a function of rotating currents or spinning motion that holds much of the packed ice in the sea for years. Ice makes it difficult to navigate most ships. (Weddell is where researcher Ernest Shackleton’s Endurance ship was crushed by ice a century ago. The wreckage was found last month.)

Over the years, Dr. Lynch’s students have conducted research on penguins from “ships of opportunity”, often sailing on cruise ships in exchange for lectures and other assistance. On the Antarctic Peninsula, these ships usually remain on the western side, and regulations limit visits to the coast to a certain set of colonies.

The January voyage was aboard a Greenpeace ship that circled the tip of the peninsula in northwestern Wedel. “This is somewhere we wanted to get to,” Dr. Lynch said. “Many of these colonies have not been visited for a very long time, if ever.”

The three researchers – Michael Wettington, Claire Flynn and Alex Borovich – used drones and manual counting to determine the number of chickens in the colonies of Joinville, Vortex, Devil and other islands.

Manual counting takes time, said Ms. Flynn, a first-year doctoral student at Stony Brook. The counters identify a specific area within a colony – perhaps a group of nests or an area delineated by bird walkways – and count all the chickens in it three times to ensure accuracy. At Penguin Point, a particularly large colony on Seymour Island, home to 21,500 chickens, the census took two days. (Adele usually produces two chickens per breeding pair each year.)

“It’s annoying to count them three times,” Ms. Flynn said. “But it’s just such an amazing place to be and such an amazing job to do.” And birds can be fun, she said, like when a hungry chick furiously chases a parent who wants food.

Adélies are among the most numerous penguin species found in Antarctica, with approximately 3.8 million nesting pairs in colonies across the continent. They use their beaks to collect small pebbles to make nests dry. The chickens hatch around November, late in the spring of the Southern Hemisphere, and the parents take turns guarding them and looking for food to vomit for their offspring. The Adelis of the Antarctic Peninsula are picky about their diet: they eat only krill, a little crustacean, although elsewhere they also eat fish.

Wings and ice, or lack thereof, are at the root of Adele’s problems on the western side of the peninsula, which is warming in part as a result of atmospheric circulation patterns originating in the warming tropics. The wing thrives in cold, icy conditions, so because warming has caused a reduction in sea ice, the wing has also become less abundant.

This leaves Adele without enough food for herself and her chicks. “The fact that they are so picky about the food on the peninsula is to their detriment because they are very concerned with the health of the krill population,” said Dr Lynch.

Populations have shrunk by up to 90 percent in some parts of the west, and Gentoo penguins, featuring bright orange beaks, have largely taken over. “They will eat everything, they will multiply everywhere,” Dr. Lynch told Gentoos. “I think of them as urban pests on the peninsula.

As the world continues to warm, models suggest Wedel and the Ross Sea in West Antarctica will be the last places to be unfavorable to Adele.

Weddell has also been proposed as a marine protected area under the Antarctic Treaty, which will further protect penguins and other life there from human activities such as krill fishing, especially as the ice sheet shrinks from warming and the area becomes more accessible. “As scientists, we want to chart where all the important biology is,” said Dr. Lynch.

Finding populations stable “does not mean that climate change is not happening in the Weddell Sea,” she said. “It just means that thanks to oceanography, it stays cold and icy, and that’s exactly where these Adeles have to live.”

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