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When Doug Smith took over Yellowstone National Park’s bird programs, he quickly realized one rare species had been slipping through the management cracks.

The common loon, known for its haunting call and ability to dive more than 200 feet, is one of the least common nesting birds in Wyoming. It’s so rare, in fact, that only 22 pairs live in the entire greater Yellowstone ecosystem. And the next closest population is 200 miles northwest.

“The Yellowstone ecosystem is an island. It’s a huge island and a great wild island, but when you get out of the public land that is Yellowstone National Park and surrounding forest and wilderness, it’s grassland and ranchland and it’s completely inhospitable to loons,” said Smith, a senior wildlife biologist with Yellowstone.

Park officials knew loons existed within its boundaries, but exactly how many there were and if their populations were increasing, stable or decreasing were all unknowns. Until now.

Through a six-year partnership between the Wyoming Game and Fish Department, Park Service and the U.S. Forest Service, largely funded by the Ricketts Conservation Foundation, biologists have learned that Wyoming’s nesting loons are likely stable, but that stability is fragile.

“It’s more important for us even now to not ignore the smaller populations that seem not important or peripheral overall, who knows, they could provide some of the genetic diversity in the future for populations to survive and thrive,” said Susan Patla, Game and Fish’s recently retired nongame bird biologist.

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To describe loon history as ancient would be an understatement. The expert divers have been around since the end of the Pleistocene age – about 12,000 years ago, Smith said.

Back then, glaciers covered most of the northern half of North America and were slowly retreating into Canada.

Loons established themselves in the frigid waters left behind, then followed the glaciers, occupying nearly every cold, clear, fish-filled lake they could find. As a result, they became extremely common throughout Alaska, central Canada and the northern swath of the U.S. And then there was the Yellowstone population.

“They got stuck here, marooned really,” Smith said. “This is a relic of the Pleistocene for crying out loud. Literally. And no one really knew that. It took us until now to go, ‘Yikes, what have we got here?’”

Other loon populations in the U.S. such as Minnesota, Wisconsin and Maine are all connected in one way to the main population in Canada. But not the Yellowstone birds.

It’s possible they were connected at one point as recently as the 1800s, said Vince Spagnuolo, a wildlife biologist with Ricketts Conservation Foundation, and one of the country’s leading loon researchers who has worked on the Yellowstone population since 2013. But human encroachment, including loss of shoreline habitat, sport shooting and lead sinkers, likely fragmented their tenuous connection with the northern portion, leaving them isolated.

An irony of common loons is that they have been documented to fly from the Yellowstone area to as far as the bottom of Baja California to spend the winter in the ocean, but when they come back to nest, they won’t travel more than about 8 miles away from where they were fledged.

“They tend to just go to the next lake or two adjacent to where they were,” he said. “That’s one of the concerns; we don’t think at this time there is any chance for support from the Montana or Washington loon populations, they’re just too far away to have individuals move into this population.”

So if the Yellowstone loons weren’t likely to meet up with their neighbors hundreds of miles away, biologists and wildlife managers realized they needed to figure out what perils the birds faced here and how to prevent a possible population crash.

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But before biologists like Smith and Patla could begin a study, they needed money. The first year, the Park Service and Game and Fish scraped together just enough to pay for one year of monitoring. The following years were paid for by Jackson-area-billionaire Joe Ricketts as part of his national effort to survey and conserve loons.

Six years later, the group documented four main threats facing loons in the Yellowstone area.

The first is human disturbance. While loons in the Midwest and eastern portions of the country have lived near and among humans for centuries, the loons in Yellowstone have historically nested undisturbed. That means as humans explore more waterways and lakeshores at higher densities, they are more likely to unwittingly bump a nesting loon from its nest.

Loons can live more than 30 years, and will only nest once a year. If the adult flees its nest, exposing an egg to the sun and deadly heat, it will be another year before the pair tries again.

This year, Forest Service officials closed Moose Lake in the Caribou-Targhee National Forest for a couple months in the summer to see if it would help the resident loons. The result? A nesting pair raised a chick for the first time in 15 years, Spagnuolo said.

If closing a lake isn’t an option, wildlife officials are trying to rope off areas where loons are nesting until the chicks have fledged. They are also building floating nests that can be moved into more secluded places, minimizing disturbances from walkers, anglers, kayakers and canoers.

One of the more surprising threats came in the form of lake trout fishing nets, Smith said.

“They have hundreds of miles of fishing net out trying to control lake trout so they don’t wipe out cutthroat trout population, but the side effect is they occasionally catch and kill loons,” he said.

When a loon – either resident or a migrant — dives underwater, becomes stuck in a fishing net and drowns.

Smith is working with fisheries biologists to avoid areas where loons are nesting and place the nets at deeper depths. They are also thinking about putting reflectors on the nets as a way to warn a diving loon to stay away.

Studies remain ongoing for the final two threats: warming lakes due to climate change and mercury contaminants.

A graduate student is currently working on a project looking at toxic algae blooms in lakes where loons are nesting. The cyanobacteria, commonly called blue-green algae, is toxic to wildlife and likely fed by warming lakes.

Researchers are also looking for elevated levels of mercury. The element is naturally occurring, but increases with pollutants. It accumulates in fish and is then lethal to birds that consume them.

The Ricketts Conservation Foundation will continue to fund work on loons in the Yellowstone area. And for now, the population appears stable.

“The biggest thing in wildlife management is whenever you have a small population, you worry about some fluke or random event — disease, three years in a row of bad weather, lead sinkers — and you lose a bunch of birds and you’re done for,” Smith said. “But I am hopeful. I’m hopeful because they’ve eked back, and we’re on it.”

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