[ad_1]
Adélie penguins have had a hard time on the western side of the Antarctic Peninsula. warming due to climate change happened faster than almost anywhere else on the planet. These and other factors have led to sharp declines in Adélie populations in recent years.
But on the east side, it’s a different story.
“It’s a complete train wreck on the western 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 population is stable and fairly healthy.”
Dr. Lynch uses satellite imagery in most of his work, but It also organizes penguin research expeditions to the peninsula, which is the northernmost part of the Antarctic continent. Most recently in January, three current and former doctoral students counted on the islands on the eastern side of the peninsula in the Weddell Sea.
Their work showed that Adélie populations there have changed little since previous censuses taken over the past two decades. This suggests that as global warming continues and Adélie populations decline in other parts of the continent, Weddell may continue to be an important refuge for birds.
Dr. “It’s a nice confirmation that where the climate hasn’t changed that dramatically, populations haven’t changed dramatically,” Lynch said.
The Weddell Sea is notoriously icy as a function of a swirling current or eddy that keeps most of the ice pack at sea for years. The ice makes it difficult for most ships to navigate. (Weddell is where explorer Ernest Shackleton’s ship, the Endurance, was crushed by ice a century ago. The wreckage was found last month.)
Over the years, Dr. Lynch’s students conducted penguin research from “boats of opportunity,” often boarding cruise ships in exchange for tutoring and other assistance. On the Antarctic Peninsula, these ships usually stay on the west side, and regulations limit coastal visits to a specific set of colonies.
The January cruise was on a Greenpeace ship that dared to enter northwest Weddell from the tip of the peninsula. Dr. “It’s a place we want to reach,” Lynch said. “Many of these colonies had not been visited in a long time, or had even been visited at all.”
Three researchers – Michael Wethington, Clare Flynn and Alex Borowicz – used drones and hand counting to determine the number of chicks in colonies on Joinville, Vortex, Devil and other islands.
Ms. Flynn, a first-year doctoral student at Stony Brook, said counting by hand takes time. The counters identify a specific area within a colony (perhaps a group of nests or an area designated by the birds’ walkways) and triple-count all the chicks in it to ensure accuracy. The count took two days at Penguin Point, a particularly sprawling colony on Seymour Island with 21,500 chicks. (Adélies normally produce two chicks per breeding pair each year.)
“It’s getting boring to recount three times,” said Ms. Flynn. “But it’s a great place to be and a great job to do.” And birds can be fun, she said, like a hungry chick chasing angrily after a parent who wants to eat.
Adélies are among the most numerous penguin species found in Antarctica, with an estimated 3.8 million breeding pairs in colonies all over the continent. They use their beaks to collect small stones for nesting in dry land. The chicks hatch around November in the late Southern Hemisphere spring, and the parents take turns protecting them and looking for vomited food for their offspring. The Antarctic Peninsula Adélies are picky about their diet: They feed only on krill, a small crustacean, but they also eat fish elsewhere.
At the root of Adélies’ problems on the western side of the peninsula is the absence of warming krill and ice, or both, as a result of atmospheric circulation patterns originating from the partially warming tropics. Krill thrive in cold, icy conditions, so as warming has caused sea ice to decline, krill has also become less abundant.
This deprives Adélies of enough food they need for themselves and their chicks. Dr. “The fact that they are such picky eaters on the peninsula is to their detriment because they are so dependent on the health of the krill population,” Lynch said.
Populations in parts of the west coast have declined by up to 90 percent, and Gentoo penguins, distinguished by their bright orange beaks, have largely taken over. Dr. “They eat anything, they can breed anywhere,” Lynch said of Gentoos. “I think of them as urban pests of the peninsula.”
As the world continues to warm, models suggest Weddell and the Ross Sea in West Antarctica will be the last places to become unfavorable for Adélies.
Weddell was also proposed as a marine sanctuary under the Antarctic Treaty that would further protect penguins and other life there from human activities such as krill fishing, particularly as the ice cover is decreasing due to warming and the area is becoming more accessible. Dr. “As scientists, we want to map out where all the important biology is for this effort,” Lynch said.
The finding that populations are stable “does not mean that there is no climate change in the Weddell Sea,” he said. “It just means it stays cold and icy thanks to the oceanography, and that’s exactly the kind of place these Adélies are meant to live in.”
[ad_2]
Source link