Loons are being threatened—this is why and how you can help

Close-up of a common loon swimming in a lake Photo by Jeremy Hynes

As a documentary filmmaker, I’m often telling stories from far-flung places, but last summer I uncovered one in my own backyard—the lake. Our log cabin looks out on the far end of Smoke Lake in Ontario’s Algonquin Provincial Park. It has a massive deck, perfect for watching the seasons change from spring to summer to fall and for soaking in the quiet. Often, our nearest neighbours are the resident loon pair, who seem to appreciate the isolation as much as we do. At night, they call to each other, a haunting sound that somehow embodies the Canadian outdoor experience. By day, in early summer, they parade their chicks on their backs as if showing them off for us. And by late August, those chicks have grown enough to practise liftoff, flapping their wings in preparation for fall migration.

Over the past few summers, I started noticing things were amiss. The calls were less frequent, the chicks harder to spot from my trusty kayak. Had the loons moved elsewhere? Or were they in trouble? The search for answers ended up becoming an hour-long documentary.

One of the first things I learned is that these majestic but mysterious birds are tricky to study; there are big holes in our understanding of where they go and what they do. “They’re a cryptic species,” says Ken Wright, a wildlife biologist and loon researcher in B.C. “They’re beautiful, amazing birds, and yet there is not much known about them.”

Part of the challenge is their elusive nature—as anyone who’s tried to predict where a diving loon might surface can attest. Also their population is widely dispersed, often in remote areas. “Loons don’t nest where there are lots of people, they fly along the ocean where we’re not really looking, and they aren’t hunted so there are no government-led monitoring programs in place,” says Mark Mallory, an Acadian University professor and a Canada Research Chair. It would take countless hours for researchers to mount a population census. Thankfully, scientists have the help of cottagers, who have easy viewing access from their docks, shorelines, canoes, and kayaks.

How can cottagers help scientists?

For more than four decades, Birds Canada has recruited cottagers to collect data for its annual Canadian Lakes Loon Survey. “One of the big advantages is that you can engage so many volunteers, and you have all these folks all over the place,” says Doug Tozer, the director of waterbirds and wetlands at Birds Canada. “You can monitor so many more lakes than you ever could with paid staff.” Over the years, cottagers and other citizen scientists have kept tabs on more than 4,000 lakes. “People volunteer to make observations of loons and, particularly, how many chicks they produce, and they report it back to us,” says Tozer. “We use that to monitor how healthy loon populations are.”

In 2021, their analysis of all of that collected data started to raise alarm bells.

Across almost all of Canada, common loons—the loon species that breeds the farthest south into cottage country—are struggling to reproduce. Adult populations are stable at about 240,000 breeding pairs, but if they cannot raise enough young to replace themselves, the future of the species is at stake. As Wright puts it: “Just because you see loons on your lake doesn’t mean all is well.”

“We’re right on the doorstep of them producing so few chicks that their populations are going to start to decline,” says Tozer, who co-authored the analysis of decades of data with fellow biologist Kristin Bianchini. “We really identify with loons as being part of Canada, and we’re going to almost lose a part of us, I think, if that happens.”

Common loon productivity (measured by how many chicks a loon pair can raise to six weeks of age) has dropped by an average 1.4 per cent per year nationwide over the past three decades and is now hovering just above the rate at which overall population numbers will start to fall. Declines are steepest in Atlantic Canada, but the downward trend persists in every province except—for reasons unknown—Quebec.

“We are really stymied as to what the mechanisms are behind those declines, and that has me worried,” Tozer says. “There are only so many loon researchers in North America. It’s a small group, so we feel a lot of pressure to figure out what’s going on.”

What hardships are loons facing during breeding season?

To understand the hardships facing loon families, our cameras followed the progress of two pairs of loons over the course of a breeding season, one pair in Wisconsin where similar long-term population studies are underway, and one in Algonquin Park. As we rolled (from a safe distance with long lenses), I found myself both impressed and concerned.

Loon parents face so many challenges in raising their young. They are excellent swimmers but move awkwardly on land, so they nest at the water’s edge where they can slip into the lake at the first sign of danger. The location leaves their eggs vulnerable to raccoons, otters, and other shoreline predators. The adults must maintain a gruelling, constant vigilance throughout the four-week incubation period. Nests can be washed out by motor boat wakes or sudden heavy rainfalls that drown the eggs if left unattended. As shorelines are developed, the number of prime nest sites shrinks, and rival intruder loons will sometimes attack, even kill, resident loons to take over a territory.

Once the eggs hatch, the workload only increases. Chicks enter the water within hours and stay on the same lake until they learn to fly in the fall—if they survive that long. Life on the open water leaves them vulnerable to predation from above in the form of birds of prey, so they need around-the-clock parental protection. Unlike adult loons, which are strong enough and have sharp enough beaks to fight off an eagle swooping down for a quick meal, chicks need help to stay alive.

Chicks also require a steady supply of fish to eat, all of it coming from a single lake. The faster they grow, the more likely they are to avoid predation. In the first several weeks, parents must do all the hunting: diving, catching, surfacing, feeding the chicks and themselves, then starting over again. Loon families require lakes with lots of fish and clear enough water to find them; two parents with two chicks can consume up to a half-ton of fish in a single season.

“You watch a loon family out on a lake and it looks really easy right? But there’s a lot that can go wrong if you’re a chick,” Tozer says. “You can starve, you can have inclement weather, you can get separated from your parents by a motorboat and then something eats you.” Since loon parents hatch only one or two young per season, every chick loss is significant.

And yet, common loons have persevered for eons. They are one of the oldest living bird species on earth, dating back 70 million years. Why are they struggling now? The biologists I spoke to, both in Canada and parts of the northern United States where similar declines have been observed, agree that human-induced environmental changes are likely at the root. And that’s what worries them most.

“Common loons winter off our coasts. They summer in our backyards at cottages, so they are very vulnerable to human activity,” says Wright. “They are showing us what the health of our lakes is.”

What are the major inhibitors to common loon reproduction?

It will take years’ more study to know for sure, but researchers have three major concerns about the lake water that loons inhabit. Mercury—a pollutant released from the burning of fossil fuels—is found in many lakes across Canada, and is a neurotoxin that makes loon parents lethargic, less able to care for their young.

Second, acid rain that fell decades ago has killed off fish stocks that have yet to fully rebound in some areas. “Loons need lots of big, nutritious organisms, in the form of fish, to survive. But those are exactly the things that got knocked out of these lakes by acid rain,” says Mark Mallory, who has studied the effects of lake acidification on loons in the Sudbury, Ont. area. Recent research shows that, even after acidity has dropped in some lakes, the loons have not returned. “Nature is very resilient, and it may take a long time for things to decline,” says Mallory. “And correspondingly, it can take a long time for things to recover.”

The third main concern is climate change. To see a nesting loon panting in the heat, beak open and breathing heavily, is heartbreaking. But biologists who study loons believe that the effects are far more insidious: among other outcomes, warming waters cause an increase in methylmercury levels and cause bacteria to be more active. As Tozer says, “Climate change is going to be the big ugly thing in the background that’s causing a lot of this change.”

Loons are especially vulnerable to environmental change because they return to the same lake where they’ve laid eggs in the past, even if conditions are deteriorating. “This is hard-wired into their genetics,” Mallory explains. “They keep trying because they’ve defended the territory and they think everything else looks good about this site.”

The loon pair our cameras followed last summer in Algonquin were able to navigate the breeding season’s many challenges and raise two healthy chicks. Sitting in an edit suite watching the parents brave swarms of blackflies to stay on a nest or delicately manoeuvre their long beaks to carefully rotate an egg was awe-inspiring. To see them underwater, turning on a dime to catch a yellow perch, is to witness them at the peak of their powers. Both chicks grew at an astonishing rate—from tiny fluff balls to juveniles almost the size of their parents. It felt like a victory despite the larger question marks about the survival of the species.

In late fall, long after we close up our cabin each year, the young loons are left to fend for themselves. Their parents migrate first, leaving them alone on the frigid waters for several weeks. They feed and grow, building strength until just before the ice comes in. Then they too take flight, on their maiden journey south, as instinct guides them to do.

I only hope it continues for generations to come. For the loons’ sake and for ours.

Julia Nunes wrote and directed the one-hour feature documentary, Loons: A Cry From the Mist.

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