Study lends insight into secret world of harlequins

Go up Avalanche Creek, take a left way upstream on a trail-less and brush-choked tributary, then look up a 25-foot cliff perched above a raging whitewater.

Sitting on the ledge just might be a harlequin duck nest, concealed with moss, the eggs covered in a plush mat of three-inch thick down.

While the showy harlequin duck male is a common sight along McDonald Creek from late April to June, the females are far more secretive and their nests are almost impossible to find.

The above-mentioned nest was discovered last summer by researchers only after they were able to track the duck using a radio transmitter attached to its back.

"Otherwise we would have never found that nest," said Lisa Bate, a lead wildlife technician at Glacier National Park.

A study by University of Montana graduate student Warren Hanson has begun to unlock some of the harlequin duck's mysteries in the Park. Hanson worked with Bate and other researchers this summer capturing and tracking Park harlequins.

Harlequins are unique ducks. Unlike most ducks, which migrate from north to south in winter, harlequins travel from east to west. They breed in the mountains of the west and then winter on the Pacific coast.

They arrive in Glacier Park in late April. This spring, researchers caught 30 birds using mist nets - ultra-fine nets stretched across McDonald Creek - that capture the birds without doing harm. Males and females were banded, and 12 breeding females were fitted with radio transmitters attached to their backs just under the skin.

The transmitters were designed to operate for a few months and then fall off as the duck's skin sloughed off. They were fitted with the help of local veterinarian Dan Savage, who volunteered his time.

"We couldn't have done this study without him," Bate noted.

Savage's services have been instrumental in other Park wildlife research, including a recent wolverine study where he also volunteered his expertise.

Even with radio transmitters attached, finding nesting females proved difficult. For one, high water made it difficult to get around and washed away many nests.

Secondly, the ducks are simply secretive.

One nest site, for example, was thought to be in a log jam, but researchers were never able to find it. In 2011, successful nests were located well up tributaries of McDonald Creek, where the water wasn't as high.

A harlequin female takes great pains to care for her eggs. Not only is the nest well-concealed, she covers the eggs in thick down and nearby mosses to keep the eggs warm - a veritable comforter of warmth. With 12 females fitted with transmitters, only two nests were found.

Being able to radio-track birds lent insight into some fascinating aspects of the bird's behavior. Researchers found that birds would spend nights on Lake McDonald - presumably for safety - and then return to nesting and feeding areas in daylight.

After they nested, researchers caught and banded 14 more fledglings and two more females.

The birds left the Park in early fall. To date, a female with a radio transmitter has been found in Puget Sound off the coast of Washington. Biologists there hope to pick up the bird's signal and do some tracking this winter.

The Park's side of the study will continue next year. Last year's study was hampered by high water and deep snow that lasted into June.

The hope, Bate noted, is that next spring has more normal conditions and the study will have better results.

The study is funded by the Park Service, the University of Montana, the federal Highway Administration and the Cooperative Ecosystem Study Unit.