Sea ducks migrate to Glacier National Park

Harlequin ducks a treat to view in Glacier National Park 

By Gail Jokerst/for Montana Living

Come springtime every year, about 100 harlequin ducks migrate to McDonald Creek in Glacier National Park. People with binoculars follow their movements, trying to pinpoint these frisky sea ducks as they dash through swift-flowing whirlpools. 

Binoculars aren’t mandatory. But once you’ve glimpsed your first Harlequin, you’ll wish you’d brought along a pair for closer inspection.

With its slate blue, white, and chestnut markings, the drake qualifies as one of North America’s most striking birds. And despite its dashing plumage, it blends magically into the scenery.  Ditto for the muted gray-brown hen, which is even harder to spot.

Though Harlequins start arriving around mid-April, the best time to sight the drake and hen comes early to mid-May. That’s also when stretches of the park’s Going-to-the-Sun Road open to foot and bicycle traffic. Drakes remain in Glacier through June then migrate back to the Pacific coast. Hens linger through August to rear their brood and prepare for the long flight west.    

Unlike most ducks, Harlequins mate for life and return to the female’s natal stream to breed. They’re also the only North American duck to breed exclusively along rushing streams and rivers. The park’s crystalline waters supply a ready source of caddisfly and mayfly larvae on which to feed. Overhanging vegetation perfectly camouflages nests. And midstream boulders offer safe resting places.

Of all the areas in and around Glacier where Harlequins occur, the McDonald drainage offers the choicest spotting opportunities as nearly half of Glacier’s Harlequins nest in this west-side drainage.

You can also glimpse Harlequins at Fish Creek in Glacier Park and along several tributaries of the North Fork of the Flathead River. Wherever you find them, don’t be surprised to see the same ducks shoot through rapids, bob downstream, and wing back upstream to ride the whitewater over again.

Old harlequin duck identified in Glacier Park

A male harlequin duck, known to be at least 17 years-old, was identified in 2013 IN Glacier National Park by University of Montana researchers and Glacier National Park scientists.

The banded duck is believed to be the third oldest on record. The oldest known banded harlequin duck has a recorded age of 18 years and 10 months. 

"Prior to these findings, harlequin ducks were reported to live up to only 10 years of age, which makes this finding a positive indicator of the health and longevity of harlequin breeding populations in Glacier National Park," said Lisa Bate, Glacier National Park biological science technician. "Research indicates harlequin ducks mate for life unless something happens to one member of the pair. This old male has returned the last three years with the same female."

In 2011, a study of harlequin ducks on Upper McDonald Creek was initiated by Glacier National Park in cooperation with researchers from the University of Montana. Researchers use radio-telemetry and banding to learn more about the location of harlequin nests and factors affecting offspring survival. Upper McDonald Creek is considered an important breeding stream for harlequin ducks, comprising 25% of known broods produced in Montana. The area also has the highest density of breeding harlequins in the lower 48 states. Glacier National Park has approximately 40 pairs of harlequins in the park. 

Harlequins are small sea ducks that spend most of their lives along the coastal waters of North America. Male harlequins are slate blue with bold white, black, and chestnut highlights. They are often referred to as "clown ducks" for their unique coloring and markings. Female harlequins are brown and gray which allows them to blend into their surrounding while they sit on their nests for 28 days. 

Each spring, harlequins migrate inland to breed and raise their young along fast-moving, freshwater streams. They are considered to be more strictly confined to running water than any other waterfowl species breeding in the Northern Hemisphere. Harlequins are slow to mature, sensitive to human disturbance and vulnerable to climate change because they select nest sites close to the water's edge. Female harlequins only breed on the streams where they were born, making the integrity of breeding sites especially important to maintain populations. The state of Montana lists harlequin ducks as a species of special concern. 

While the harlequin duck study within Glacier National Park will conclude this fall, scientists throughout North America will continue to survey and collect information from banded harlequins. A University of Montana graduate student is expected to publish a thesis regarding the park study near the end of this year.