For more than 30 years, Vermont scientists have been setting up floating rafts where loons can build their nests.
When one of the first rafts was deployed on Kettle Pond in Groton State Forest in 1992, there were just seven nesting pairs in Vermont.
But now, scientists with the state’s loon conservation program are starting to pull those rafts out of lakes. They say loons are doing so well that it’s time to let them nest without human aid.
“This species is sort of our indicator species,” said Roz Renfrew, who leads Vermont’s Wildlife Diversity Program. “They're showing us what's going on, and that we've had so many people's interest and attention has really been what's really made the difference.”
In 2025, loons had a banner year in Vermont. Volunteers counted a record 402 adults, a record number of successful nests and a record number of chicks. More of those chicks survived their first year than in any year since scientists started counting.
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Most importantly, scientists say, Vermont’s loon population is averaging more than one chick per loon territory every other year — which indicates the population is more than sustaining itself at a healthy pace.
Removing the rafts does involve a bit of risk, researchers say. When loons build their nests on rafts, they have an 86% success rate, as compared with 75% in a nest built on a natural island or as little as 50% for a shoreline nest.
But those figures reflect healthy population dynamics, says Eloise Girard, a loon biologist with Vermont Center for Ecostudies who is removing rafts this summer.
Girard says biologists are seeing loon behavior change. There are so many more loons on the landscape that Girard says scientists are starting to see signs they are competing for territory.
Sometimes the birds resolve these disputes through peaceful negotiations mid-lake between chatting mated pairs. However, they can also escalate into violent duels, where birds fight underwater, diving like torpedoes to stab an opponent in the sternum.
“Even though the loon population is doing well, it's important to just keep monitoring them because there are still a lot of threats that they're facing, and some are new ones,” Girard said. Those threats include climate change and chemicals like PFAS that threaten water quality.
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And while Renfrew says Vermont has done the right things to support loons — like banning half-ounce lead sinkers, which poison the birds when they swallow them, and offering rafts as insurance to make nests more successful, as well as conserving shoreline — she says federal policy ultimately saved them.
Loons declined largely because they were being poisoned by mercury in freshwater fish that was deposited in lakes from air pollution. At the same time, acid rain was also hurting freshwater fish populations. The Clean Air Act may just be what saved the birds — a piece of federal regulatory policy that the Trump administration has tried to weaken in recent years.
Scientists at first had misgivings about making Vermont loons dependent upon the rafts, but Renfrew says they’ve proved a crucial tool.
“Oftentimes species will be struggling for multiple reasons and so you take the reasons that you have the most control over and try to ameliorate those,” she said.
Biologists plan to remove a few rafts every year over the next decade, but will keep them in place on reservoirs where water levels fluctuate and as a tool to deter the birds from building unsuccessful nests in places that are very developed.
