GLACIER NATIONAL PARK — With their signature plumage rivaled only by the beauty of their migratory mountain homes, it’s easy to see why harlequin ducks have captured the hearts of countless birdwatchers and casual observers, alike.

One area native has made these magnificent birds the focal point of his life for the past three years, studying harlequins in Glacier National Park for the thesis of his wildlife biology master’s program at the University of Montana. Warren Hansen, a graduate of Polson High School, has channeled his lifelong love of ducks and the outdoors into a long-term examination of harlequins in the park’s McDonald Creek watershed – a renowned hotspot for harlequin breeding activity.

The rare birds are sea ducks that typically spend their winters residing in roaring coastal surf zones before migrating inland to nest right alongside whitewater mountain streams that mimic their marine habitat.

“They’re the only bird to have an east-west migration,” notes Hansen.

In McDonald Creek and its pristine tributaries, the harlequins have found an ideal habitat.

“McDonald Creek has the highest breeding density of harlequins in the Lower 48,” Hansen says, with a ten-mile stretch of the stream hosting an estimated 20-40 breeding pairs – approximately a quarter of Montana’s population.

While their relative abundance may suggest that Glacier’s harlequins are thriving, Hansen has dedicated his master’s thesis to examining the species’ vulnerability to stream flow variation and human disturbances - two key factors that may potentially threaten their well-being and reproductive success.

Hansen has gone to great lengths to study harlequin nesting sites scattered throughout the McDonald Creek watershed, occasionally scaling cliffs or becoming inadvertently surrounded by grizzly bears in the process.

While it has been an adventure at times, Hansen has found the harlequins are up against some significant challenges.

Due to the species’ heavy reliance on synchronizing their migration with peak runoff for mountain streams, Hansen says that climate change – and, consequently, the greater unpredictably of stream flow – makes harlequins vulnerable.

Hansen’s research has found evidence to suggest that in some cases “nests may be getting flooded out by these fluctuating stream flow levels,” reinforcing speculation that changing patterns in temperature, snowpack and precipitation may “significantly impact the success rate of reproduction of harlequins.”

Another chief component of Hansen’s study addresses the impact that human disturbances have on the species. With millions of visitors crowding into Glacier National Park each summer, Hansen says that the ducks are often shunted away from what is otherwise marquee habitat.

“Maybe the ducks are able to find ideal habitat elsewhere, but maybe not. Maybe they’re displaced into poorer quality stream reaches,” Hansen says.

Despite the challenges facing the species, Hansen is “generally optimistic” that they demonstrate enough natural variation and resilience to persevere in the face of uncertainty, especially if conservation efforts are continued into the future.

Through the grind of all his research and analysis, the simple joy of seeing harlequins has not been lost on Hansen, who still marvels at the majesty of the species.

“You can’t take your eyes off them. They’re so beautifully painted, and they have such a unique personality that you can watch them all day,” Hansen says.

“Not many people do see the importance of preserving a single species,” Hansen says before expressing hope that the popularity of harlequins could help catalyze their own preservation, while also benefiting other species, too.

“Using megafauna or a sexy species to conserve habitat encompasses a lot more than just harlequins,” Hansen points out.

“They are very much in the public eye and I think that the public’s best interest is whatever will help these ducks continue to persist into the future.”