Turbo, an 18-inch-tall Patagonian penguin with a white belly and black-banded chest, has been a bachelor for all his adult life.
That is just one of the many findings Boersma has made about how the lives of the Magellanic penguins she has been studying for four decades are changing. In her most recent study about the largest breeding colony of these penguins, in Punta Tombo, Argentina, she and a co-author report in Ecology that chicks are spending less time in the nest.
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Female penguins are arriving later in the September-October period to lay eggs — possibly because there is less food or because they are having to swim farther to find fish to eat. So chicks are born later but still must leave the nest at the same time of year to catch fish before nutrient-rich tidal fronts dissipate.
Penguins “are the classic canary in the coal mine,” said Doug Morris, a biologist emeritus at Lakehead University who was not involved in the study. “They give us a window into seeing changes in marine environments that we might not otherwise be able to see.”
Those changes include climate change, which is causing rising ocean temperatures and acidification, and changing wind patterns — shifts that, along with increased commercial fishing, are probably contributing to the penguins’ struggle to find food.
This latest study found that younger chicks — those with smaller bills, flippers or feet — are more likely to perish at sea. With shortened time in the nest, chicks are having “to do all of their growing to reach a size and maturity where they can have some chance of surviving in the ocean faster than they did 30 to 35 years ago,” said research scientist Ginger Rebstock, who was not involved in the study.
Boersma started studying the penguins in 1983 and has watched their numbers fall from about 400,000 breeding pairs to 170,000. Food scarcity is just one of the emerging threats.
Increased rainfall and extreme heat also have taken their toll.
Heavier rain kills chicks when their down becomes soaked and their body temperature plummets. Hotter days bring increased danger, as well. In 2019, researchers recorded a temperature of 44 degrees Celsius (111 degrees Fahrenheit) in the shade at Punta Tombo — one of an increasing number of abnormally hot days. They watched 264 adult penguins and 90 chicks die in a single day.
Boersma recounted all this from the Indianapolis Zoo, where she had been honored as a 2021 Indianapolis Prize finalist for her conservation efforts. She paused during the conversation to listen to a male lion roaring at a female lion.
“We’ve banded probably 60,000 penguins over the last 37 years,” she said. “Climate change is an important factor in their survival and their success.” Boersma stopped again to listen to a walrus call.
The finding that chicks are leaving the nest earlier is from data collected between 1983 and 2017. Boersma and research students regularly checked the nests of banded Magellanic penguins for chicks. Like hospital midwives, they marked the newborns with temporary identifying bands, and then with stainless-steel tags on the outer webbing of the penguins’ feet. They measured the chicks’ wing and bill length with a ruler and calipers.
Boersma and her colleague Caroline Cappello found that over those decades, hatch dates shifted 10 days later. Yet the chicks still typically went into the ocean in late January to early February, despite being generally younger and smaller. They also found that over this period of 34 years, only 46 of 542 banded fledglings returned as juveniles the following year — that is, 8.5 percent.
A surprising finding was that in more recent years, younger chicks were heavier and in better condition when they first left the nest. The study offered two possible reasons for this. With the shortened period in the nest, it is possible that only the best quality chicks are surviving. Also, with the significantly reduced population, each individual penguin chick may now be slightly better fed. The study calls for further research into this phenomenon. The overall picture remains bleak.
“The main reason the colony is declining is that it’s no longer as ideally situated for foraging as it was when it first got established,” said Gordon Orians, a biologist emeritus at the University of Washington who was not involved in the study. “The fact that they have to go farther for food now and are having more trouble is almost certainly related to some degree to climate change.”
Previous research has linked climate change to some — but not all — shifts in key life-history events of animals and plants. By observing Magellanic penguins for so many decades, Boersma and her collaborators have been able to observe changes occurring in various life events in a single species.
“The overall study is an unbelievably long-term record of a colony,” Orians said. “It’s a treasure trove. There are very few long-term studies that can match that.”
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To many observers, the disappearing penguins presage worrying changes to marine ecosystems. Magellanic penguins face multiple threats, such as overfishing, which reduces food supply and traps penguins in nets, oil pollution and plastics.
“Penguins don’t eat anything on land — all of their prey comes from the ocean,” Rebstock said. “If they’re not doing well, we know that something’s wrong with the ocean.”
Some scientists argue that as climate change accelerates, people need to do more to help species such as penguins fight these multiple other threats to their survival.
“This study fits into a broadening understanding of both climate change and its effects,” Morris said. “But also the more serious problem . . . of global extinction of biodiversity.”
“The world’s attention seems to be related to can we keep global temperature rise to 1.5 degrees Celsius or less,” he said. “But meanwhile, every day we are learning about . . . thousands of species imperiled and going extinct.”
“If our emphasis was on preserving the Earth’s biodiversity, we wouldn’t have a climate problem,” he said. “But if we solve the climate problem, we’re still going to have problems with biodiversity.”
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