The Harlequin Duck: The Costumed Duck of Swift Mountain Streams

Guest Blog | habitat, water species, and wildlife | March 2019

What Do They Look Like?

If you find yourself near the Alberta Rockies exploring a mountain stream with fast, clear, turbulent water and see a duck feeding in the white water rapids, you may be wondering what waterfowl could possibly choose to live in these conditions. There are only four ducks in the world that are adapted to fit this highly specialized lifestyle and only one in North America¹ — the harlequin duck. This duck is found during breeding in and around Alberta’s Rocky Mountains. It’s breeding ranges extends from Waterton Lakes in the south up to the Kakwa River in the north.²

The male harlequin duck is quite a sight in its breeding plumage. It gets its name from a character from Italian comedy in the 1500s that wore a bright, checkered costume. This is fitting as the duck has quite the costume itself; the males being slate blue with bold white, black, and chestnut markings. The most distinctive markings are on the head in the form of a crescent-shaped white patch at the base of the bill; a round, white ear patch; and a white vertical stripe along side of the neck. The female doesn’t quite have the colouration of the male but still has the round, white ear patch. It is quite a small duck being about half the size of a mallard. Juvenile birds look very similar to the females except have yellow feet, as opposed to the gray of adult birds, and brown bellies instead of white with brown streaks.³

Migration and Breeding

The harlequin ducks found in Alberta spend the fall and winter on rocky coastlines along the Pacific Ocean where they reform pair bonds from previous years.⁴ Any harlequin ducks that have mated before do not seek a new mate as this species mates for life. According to a 2015 study, if the previous mate is alive, the evidence suggests that they always seek out this mate again, only finding a new mate if the previous mate has died.⁵ If the ducks haven’t mated before they typically wait until spring and then find a mate before they head to the breeding grounds.

In April or May, the ducks head for the high elevation, clear mountain streams inland; some of these streams falling in the Rocky Mountains and foothills of Alberta. Any pairs that bred previous years return to the exact same location they bred the year before according to study performed in British Columbia in 1999. The purpose for this site fidelity is probably to aid in the survival of the birds through local site knowledge. This allows birds to better understand the location of the best food sources, the location of predator populations, and the movements and patterns of predators.⁶

When selecting a nest site it is the female that finds a suitable location with the male sometimes accompanying. In the Kananaskis Country a 1997 report found that the males waited at the confluence of larger watersheds while females selected sites in smaller tributaries.⁷ The nests are on the ground, near water and usually protected from above. In Alberta, they have been found in crevices, under rocks, and within driftwood piles.⁸

Harlequin ducks typically have a clutch of 5 to 7 eggs after which the male leaves for the wintering ground; usually in June or early July in Alberta. It is believed that the male leaving improves the chances of survival by limiting the number of ducks feeding in one area.⁹ The males and females are then separated for 2 to 4 months before they meet again at the same wintering area as the year before where they reform pair bonds again.¹⁰ The female and young all leave together and make the trip back to the Pacific Ocean as a group.¹¹

Behaviour and Adaptations

Harlequin ducks have evolved to thrive in the harsh environments that they are found. They have adapted to be excellent divers to survive in the rough waters and many storms found at their wintering grounds. For foraging in their wintering areas, harlequin ducks have adapted a type of nail on their bill that they use to pry limpets and chitons off of rocks; this is extremely difficult to do and no other duck is known to be able to accomplish this. Another unique adaptation of harlequin ducks is their behaviour of perching on the top of rocks to rest instead of resting in the water like most sea ducks. This could be to help them conserve and replenish energy in the rough waters they live.¹²

Harlequin ducks forage by diving or dabbling to catch their aquatic insect prey.¹³ At times they will even walk along the bottom of the stream, searching under rocks for their next meal.¹⁴ The outstanding swimming abilities of harlequin ducks allow them to easily navigate the white waters that they find in their breeding range as they are in search of food.

Conservation

Competition With Other Species

A 2009 study in British Columbia looked at the competition between fish and harlequin ducks for the same food source and how that might affect success of harlequin ducks. Interestingly the study did find a correlation between a decreased numbers of birds in areas with more fish present. The conclusions drawn were that it was not because of a decrease in the food source but because of a change in the behaviour of the food source. For example, they pointed out that the presence of mottled sculpin caused stonefly nymphs — a food source of both the sculpins and the ducks — to spend less time on the sides and tops of rocks and moving on the stream bottom.¹⁵

One 2005 study in the Maligne watershed of Alberta showed that the harlequin ducks are distributed in the Maligne River where the largest quantity of stonefly nymphs are located. This means that the Harlequin ducks are concentrated in the Upper Maligne and Lower Maligne and not in the Middle Maligne where rainbow and brook trout — both introduced to the watershed by humans — keep stonefly populations lower.¹⁶

These studies highlight the unforeseen and unpredictable consequences of changing an ecosystem which we should try and learn from. For example, the North Ram River is a known breeding area for harlequin ducks and has historically not contained any salmonid species because of a natural barrier in the form of a waterfall. We changed this ecosystem by introducing cutthroat trout that have thrived in this ecosystem. In this case, there is not enough data to say whether the cutthroat trout have negatively impacted the harlequin duck populations but it just highlights how seemingly innocent changes we make to an ecosystem can have unanticipated negative effects.

Nesting Interference From Recreation

Various human recreational activities have been suspected to negatively affect harlequin duck breeding success including hiking, camping, canoeing, and fishing; however, the studies are not conclusive and the effects are poorly understood. White water rafting is a popular pastime in some of the breeding range and this activity has been shown to disturb nesting harlequin ducks in the Maligne River in Jasper National Park.¹⁷

Habitat Loss

Habitat loss is the most significant threat to harlequin ducks. These amazing birds have a very specific habitat that they have adapted to thrive in and changes or degradation of this habitat can have large effects on the species.

Harlequin ducks are susceptible to changes in wintering habitat through oil spills. The Exxon Valdez ran aground on 24 March, 1989, spilling nearly 42 million liters of crude oil into Prince William Sound. This event had drastic impacts on harlequin duck populations, killing 1298 to 2650 harlequin ducks from oiling and having much greater effects over time.¹⁸ A 2010 study found that it took 11 to 14 years for harlequin duck survival rates to come back to normal and that it would take and estimated 24 years for the populations to recover completely.¹⁹ This event has taught us the dramatic consequences that an oil spill can have.

Forestry in the breeding habitat of harlequin ducks can also impact the species through destruction of habitat. Logging can degrade the habitat and remove possible nesting sites as well as increase siltation in the river. This increased siltation has been shown to cause female harlequin ducks to abandon the area. Studies have shown that unharvested sections of streams and rivers have higher breeding densities of harlequin ducks than harvested sections.²⁰

Mining can also impact the habitat of harlequin ducks and the food supply through declines in invertebrate populations. As well, a 2007 study from Gregg River — a river in the Athabasca River watershed — found that the hatchability of harlequin duck eggs was likely decreased by selenium contamination from upstream coal mines.²¹

Sediments can enter the rivers and streams harlequin ducks breed in, impacting populations of the aquatic invertebrates that they rely on as their food source. A combination of industrial roads, stream crossings, logging, irresponsible OHV use, and agriculture deposit more and more sediment into this ecosystem, degrading the habitat for all species that rely on it.

What Is Being Done to Protect Them?

The harlequin duck is a species of special concern in Alberta listed as sensitive meaning that there is concern in the long term numbers of the species.²² The reason for this listing is because of population declines due to a multitude of factors. Some of the factors are human caused disturbances on the wintering grounds such as the Exxon Valdez oil spill, possible disturbances during nesting due to human recreation, and degradation of breeding habitat through forestry, resource extraction, and agriculture. Being long-lived with low productivity means that every death has an impact on the species.

The Provincial and Federal government has taken few steps in protecting these Alberta ducks. There have been no restrictions put on hunting the species, however, harlequin ducks are rarely taken by hunters due to their location and timing with hunting season. One move that has been made is restrictions were put in place on rafting in key areas. In 1999, Jasper closed parts of the Maligne River to all watercraft and Alberta restricted the use of watercraft in key areas and at key times in the Elbow, Sheep, and Highwood Rivers.

Beyond the watercraft restrictions, the mitigation measures are more studies and monitoring without any concrete action or timelines.

How Can You Help?

What can each of us do to help this amazing duck? We can limit our individual impact on these birds by being careful not to disturb them during breeding and being careful not to destroy nests. The main issue for this species, however, is habitat degradation on the wintering and breeding grounds. This can only be fixed by speaking up and telling your government representatives that keeping industrial development out of key wild areas is important and that limiting the transportation of oil through important river and ocean habitats is crucial.

This spring, if you find yourself in a swift mountain stream in Western Alberta, keep a close eye for a beautiful costumed duck and take some time to observe its fascinating behaviour.

Original post by Jays & Graylings

https://www.jaysandgrayling.ca/blog/the-harlequin-duck-the-costumed-duck-of-swift-mountain-streams

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