- When they make their first journey into the ocean, fledgling Atlantic puffins are prone to being stranded on land, imperiling them. For years, scientists have wondered what leads to these strandings.
- A new study provides experimental evidence to show that artificial light lures young puffins toward land, contributing to strandings.
- The study found pufflings don’t have a strong preference for any particular light source or color. However, once stranded, they move more under darkness and high-pressure sodium lights than under LED lights.
- Reducing artificial lights along the coast and offshore could save puffin lives, say conservationists, as Atlantic puffin populations are decreasing in parts of Europe. It can also save other threatened seabirds, such as Leach’s storm petrel found off Canada’s coast.
As the long summer days of August turn into nights, a few dozen volunteers gather in the small community of Witless Bay, a tiny town on the Atlantic coast about a half-hour’s drive south of St. John’s, capital of the Canadian province of Newfoundland and Labrador. After a briefing by a coordinator from conservation NGO the Canadian Parks and Wilderness Society (CPAWS), the volunteers don reflective vests, grab butterfly nets and flashlights, and place plastic crates in their cars. They then set off scouting the 15-kilometer (9-mile) coastline for tiny, black-backed pufflings, the name for baby Atlantic puffins (Fratercula arctica).
It’s a daily ritual for the Puffin Patrol, a grassroots movement that began in the 2000s and now comprises nearly 1,000 volunteers every August. That’s when fledging Atlantic puffins from North America’s largest colony of the species, Witless Bay Ecological Reserve, leave their burrows for the first time. Under the cover of darkness, hiding from their predators, the tiny birds venture into the ocean, where they spend the next four years of their lives before coming ashore to breed.
Atlantic puffins also breed in parts of the northeastern U.S., the U.K. and northern Europe. Lifelong monogamous pairs return to the same burrow each year and lay a single egg. Both parents raise the chick for about three months before the young leaves the colony.
On this journey, most pufflings find their way to the ocean. A few (less than 1%, according to a 2021 study) instead end up on land. These are the targets of the Puffin Patrol. Without help, the stranded puffins are likely to be run over by cars or fall prey to stray cats or wild foxes. But once in the safety nets of the patrol volunteers, the seabirds get a free boat ride to their colony, where they’re returned to the sea.
Puffin strandings during the fledgling season have puzzled scientists on both sides of the Atlantic for years. In Iceland, the Faroe Islands and other parts of Europe, where the Atlantic puffin is listed as endangered on the European Red List of Birds, strandings have increasingly become a concern for conservationists.
“It’s been fairly obvious that [puffins] are attracted to light,” says seabird biologist Ian Jones from the Memorial University of Newfoundland (MUN), Canada, who has studied seabirds on the Atlantic coast for more than four decades. “There were a lot of anecdotes but we didn’t really have any definitive, very carefully controlled experiments to test whether this was the case.”
Now, a new study published in the journal Animal Behaviour provides the first such evidence. Through three behavioral experiments, the researchers found that Atlantic puffins are indeed attracted to artificial light at night (ALAN), and more puffins become stranded when beaches are illuminated than when they’re dark. The birds didn’t show a preference for a particular light source or light color in the experiments, but seemed more active and mobile on land in the darkness than under LED lights.
“These experiments seem to indicate that [Atlantic puffins] are attracted to light, and that’s what’s bringing them into towns,” says study lead author Taylor Brown from Trent University, Canada. “Atlantic puffins in the eastern Atlantic are declining, so the light attraction may be an important thing to try and address there, which is what I hope my research can help with.”
Drawn to the light
Artificial light at night (ALAN), either on or off coast, is known to impact the behavior of baby sea turtles, insects, various forms of marine life, nocturnal pollinators, and birds, including seabirds. As energy-efficient LEDs become widespread and coasts become ever brighter, ALAN can disrupt circadian rhythms, change nighttime behaviors of animals and birds (not to mention humans) and disturb their hormonal balance. While scientists understand how ALAN affects other seabirds like petrels and shearwaters, little is known about its impact on smaller seabirds like puffins.
In the first experiment as part of their study, Brown and colleagues shone a bright LED light on two beaches facing the puffin colony in Witless Bay for a couple of hours on alternate days for 11 nights. On days when the beach was illuminated, they found tens of pufflings near the beach. However, when the beach was dark, they found nearly none. This showed that the seabirds are markedly attracted to light.
To examine their preference further, the researchers placed stranded puffins, retrieved by the Puffin Patrol volunteers, in what’s known as a Y maze.
“It’s an experiment that’s meant to test preference of movement of these birds,” Brown says, describing the experimental setup that consists of a Y-shaped tunnel. They placed each bird at the bottom of the Y. One of the arms at the top had a light source, and the other was dark, with the puffling free to choose which one to move toward.
“Puffins are generally pretty curious, gregarious, active animals, so it wasn’t too difficult to get them to move through the Y-maze,” Brown says about their experience. As it turned out, all the puffins put through the maze chose light over darkness, further confirming their preference for light.
The researchers then tested whether the birds preferred a particular light source, such as high-pressure sodium lights or LED lights, or color. They again used the Y-maze with various combinations of light sources and colors to test the pufflings’ preferences. The birds didn’t seem to care about the spectrum of light, with no marked preference between warm white, blue, orange and cool white light, nor did they prefer a light source.
Interestingly, the pufflings seemed to be more mobile — pacing around the experimental area — in darkness and under high-pressure sodium light than under LED lights. The researchers say this behavior would make it easy for the birds to be spotted under darkness and the dim sodium lights.
“This is really good science,” says Jones, who wasn’t involved in the study. “Science works through an objective process, facts and controlled experiments and very careful conclusions, drawing from that, and this is what they’ve done here.”
When asked why only a fraction of pufflings get stranded on the coast of Newfoundland, while most seem to be just fine, study co-author Sabina Wilhelm, a seabird biologist with the Canadian Wildlife Services, says that while the birds disperse at random when they make their way to the ocean, those that get lost and move closer to land are further attracted to the light.
“It’s not long-range attraction,” Wilhelm says.
Since the pufflings’ vision isn’t adapted to see well at night, Wilhelm posits they get attracted to light because it makes them feel safe.
“On a night where there’s a fog, or there’s no moon, and it’s just pitch dark … you see something [bright], naturally you’ll go in that direction because it’s something versus nothing,” she says.
Reduce artificial light to save seabirds
The IUCN Red List categorizes Atlantic puffins, the only puffins native to the Atlantic Ocean, as vulnerable. As the climate crisis warms the oceans, puffins are seeing their prey driven further north. In addition, marine pollution is impacting their habitat. This has led to decreasing numbers in the eastern Atlantic. In the western Atlantic, however, their numbers seem to be healthy, for now.
“We always feel like we are on the tipping edge,” says Wilhelm, who studies seabird populations in Atlantic Canada, as the threat of avian flu currently looms large and starvation killed many chicks in 2023.
The study’s findings also have implications for puffin conservation as they show that artificial light could increase strandings, and the only way to reduce them is to turn the lights off on the coasts during the fledgling season.
“The most affected and the most important areas to avoid increasing light pollution would be areas immediately adjacent to the colonies, where the birds are fledging and where they’re most likely to end up by chance,” Brown says.
On the “bright” side, stranded pufflings’ attraction to light could also help focus rescue efforts on brightly lit hotspots where they’re more likely to be found in large numbers.
“Instead of looking for birds across this huge coastline, you can actually try to get the majority in one area,” Wilhelm says, talking about how the study’s findings could inform efforts like the Puffin Patrol. “It really becomes more efficient to save them.”
Reducing artificial light along Newfoundland’s coast also benefits another vulnerable nocturnal seabird: Leach’s storm petrel (Hydrobates leucorhous), whose numbers have halved in the last four decades. Artificial light, on the coast and off the coast on oil rigs, has led to many birds being drawn into towns, run over by cars, or banging into structures and injuring themselves.
“Once a seabird is injured, there’s no emergency room that a seabird can check into,” Jones says, adding that Leach’s storm petrels are dying by the thousands and that this is a critical concern.
“A global awareness of the problem of artificial light … is urgent,” he says. “It’s time for drastic action to reduce light offshore and on our shorelines to save the storm petrel, and certainly that’s going to save a few puffin fledglings as well.”
Banner image: An Atlantic puffin (Fratercula arctica) on Skomer Island, Pembrokeshire, Wales. In the western Atlantic, puffins have drastically declined in recent years, partly due to climate change. Image by Charles J. Sharp.
For threatened seabirds of NE Atlantic, climate change piles on the pressure
Citations:
Wilhelm, S. I., Dooley, S. M., Corbett, E. P., Fitzsimmons, M. G., Ryan, P. C., & Robertson, G. J. (2021). Effects of land-based light pollution on two species of burrow-nesting seabirds in Newfoundland and Labrador, Canada. Avian Conservation and Ecology, 16(1). doi:10.5751/ace-01809-160112
Brown, T. M., Wilhelm, S. I., Slepkov, A. D., Baker, K., Mastromonaco, G. F., & Burness, G. (2024). Navigating the night: Effects of artificial light on the behaviour of Atlantic puffin fledglings. Animal Behaviour, 218, 135-148. doi:10.1016/j.anbehav.2024.09.008
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