Penguins become marine detectives, thanks to pollutant-detecting anklets

20 04 2026 | 14:50Humberto Basilio / NATURE

Along the coast of Argentine Patagonia, Magellanic penguins (Spheniscus magellanicus) spend their days shuffling across pebble beaches, plunging into the Atlantic Ocean for anchovies and sardines, and returning to the noisy colonies they call home. But a few dozen of these seabirds have also become marine detectives, sporting a soft silicone band on their ankle that absorbs traces of “forever chemicals”—toxic industrial compounds that can hang around for decades, harming both humans and wildlife.

Already, these unwitting toxicologists are showing promise in tracking forever chemicals, known as per- and polyfluoroalkyl substances (PFAS). The compounds—used in products ranging from waterproof clothing to food packaging—are resistant to heat, water, and degradation. They persist in the environment for decades and travel long distances by air and sea, posing risks to Patagonia’s coastal species. In a pilot study published last month in Earth: Environmental Sustainability, 91% of the Magellanic penguins’ bands detected at least one industrial pollutant where the birds swam and nested.

The new study is a first step toward understanding this persistent but underexplored ecological problem, says biologist Esteban Frere at the National University of Austral Patagonia, who was not involved with the work. “There are very few studies on the presence of PFAS in Patagonia,” he says, “and we know even less about their negative effects on penguin health.”

“We have no better way of understanding the ocean [these animals] live in than letting them tell us the story themselves,” says study co-author Marcela Uhart, a veterinarian at the University of California, Davis. The penguins, she says, “are now our elite team of marine detectives.”

To detect environmental hazards early, scientists use “sentinel” animals whose health, behavior, and chemical exposure act as biological warning systems. Until now, only a handful of species, including dogs, eagles, and horses, have been used to monitor PFAS.

Uhart’s team turned to penguins because they regularly move through remote marine environments that are difficult for humans to sample. They’re also particularly vulnerable to PFAS exposure because the contaminants tend to accumulate in animal tissue. As top marine predators, the birds eat several species of fish that are themselves enriched in pollutants, causing the toxic compounds to rapidly build up in their tissues.

But monitoring PFAS in penguins has traditionally required drawing blood, pulling feathers, or collecting samples of guano from remote breeding colonies. Besides being stressful for the animals, “a blood sample only tells you what the penguin ate and metabolized, not what it comes into contact with in its environment,” Uhart says.

Seeking both better samples and a more humane detection method, Uhart’s team fitted penguins with soft silicone bands loosely placed around one of their ankles. Silicone acts as a passive sampler that absorbs chemicals present in the surrounding environment, allowing the bands to record the contaminants penguins encounter in their daily lives. Similar bands have already been used in experiments with firefighters to detect chemicals they are exposed to during fires. “It’s a useful, accessible, and inexpensive technology that was already within reach,” Uhart says.

The team placed the bands on 55 penguins in two colonies along the Patagonian coast of Argentina during three breeding seasons between 2022 and ’24. The devices remained on the birds for between 2 and 9 days before the team retrieved them and analyzed them in the laboratory. The researchers screened the bands for 40 different PFAS compounds.

The results showed that most of the penguins had been exposed to these contaminants. The scientists detected PFAS in about 91% of the bands and identified nine different compounds, including both highly toxic legacy PFAS used before 2000 and newer replacement chemicals, which are less likely to accumulate in tissues but are still highly persistent and in widespread use today. Exposure also varied between colonies, seasons, and the length of time the bands remained on the birds, suggesting marine PFAS levels change across space and time.

Penguins are particularly suited for this work because they forage across large areas of the ocean but reliably return to the same breeding colonies, making it possible to deploy and retrieve monitoring devices. But Uhart and her colleagues hope to expand their network by placing the samplers on other species. Next on the list: cormorants, birds capable of diving more than 50 meters below the surface, deeper than penguins can go.

But Uhart emphasizes that the penguin study was only a pilot, with a small sample size and study period. Even so, the technique’s low cost means it could be replicated in larger penguin populations and across more regions, Frere says. “Not all of the Argentine sea is the same.”

Despite the pilot’s small size, Dee Boersma of the University of Washington sees promise in the idea. She notes that penguins are more than mere monitors for their habitats. They’re also charismatic species that can quickly capture human attention and deliver an urgent message. “We don’t really know what these chemicals are doing—but penguins are in trouble,” she says. “We’re losing our sentinels.”

doi: 10.1126/science.z7009y4

Cover photo:  During the breeding season, Magellanic penguin colonies along the coast of southern Argentina’s Chubut province can reach up to 640,000 pairs

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