Harlequin ducks are small sea ducks that inhabit coastal waters in the northern regions of North America, Europe, and Asia. They get their name from their striking and colorful plumage, which features shades of blue, white, and chestnut. Harlequins are excellent divers and swim underwater to catch their prey. But what exactly do harlequins eat? The answer is that yes, harlequins do eat fish as their primary food source.
Natural History of Harlequin Ducks
Harlequin ducks belong to the genus Histrionicus in the seaduck tribe Mergini. There are two recognized subspecies, the eastern harlequin duck (Histrionicus histrionicus histrionicus) and the western harlequin duck (Histrionicus histrionicus pacificus). They breed along fast moving streams and rivers and then migrate to coastal waters to overwinter. Their breeding habitat is quite specific – they require cold, turbulent streams with plenty of rocks and rapids. This rocky habitat provides nesting sites and helps guard the ducklings against predators.
Range and Distribution
Harlequins are found along the northern coasts of Europe, Asia, Alaska, and Canada. In North America, their breeding range extends from central Alaska across Canada to Labrador and Newfoundland. They winter along the Pacific coast from Alaska to California and along the Atlantic coast from Newfoundland to North Carolina.
The eastern harlequin duck breeds in eastern Canada and winters primarily in Atlantic Canada and Maine. The western harlequin duck breeds in western North America, including Alaska, western Canada, and the northwest United States. They winter along the Pacific coast from southern Alaska to central California.
Habitat and Ecology
As discussed above, harlequins require fast moving streams and rivers for breeding. Their nests are built along mossy stream banks, rock crevices, or hollow logs. Harlequin ducklings hatch in late spring or early summer. Soon after the ducklings hatch, the female leads them from the nest to the stream, where they immediately begin swimming and diving. Harlequin ducklings are able to dive underwater to find food and avoid predators within just a day or two after hatching.
After breeding, harlequins undergo a dramatic habitat shift. They migrate to coastal marine habitats to spend the winter, including rocky shores, reefs, and jetties. Here they form large flocks and feed in the nutrient rich waters. This marine habitat provides them with ample food sources through the winter months.
Diet and Feeding Ecology
Now that we’ve covered some background on the natural history of harlequins, we can dive into their diet. As their habitat range indicates, harlequins are specialized for swimming and diving in fast moving streams as well as coastal marine environments. This gives them access to a wide range of food sources. But fish make up the majority of their diet during all life stages.
Ducklings
Harlequin ducklings begin diving and feeding on aquatic invertebrates almost immediately after hatching. This includes small crustaceans and insects. However, they switch to eating primarily fish once they reach 4-5 weeks of age. Their early ability to dive and catch fish gives the ducklings a survival advantage.
Juveniles and Adults
Both juvenile and adult harlequin ducks feed predominantly on fish. They are capable of diving up to 20 meters in depth to find food, but most of their dives are in the range of 2-8 meters. Their dives also tend to be brief, lasting just 15-30 seconds.
On their breeding grounds, they eat a wide array of fish species including minnows, suckers, sculpins, trout, and salmon eggs. Once on their coastal wintering grounds, they switch to feeding on small saltwater fish like herring, sand lance, capelin, and rockfish. They also supplement their diet with marine invertebrates like shrimp, crabs, mollusks, and sometimes aquatic plants.
But no matter the specific habitat, fish make up at least 50% and up to 90% of their food intake. The proportion of invertebrates vs fish varies based on seasonal and regional availability.
Feeding Behavior
Harlequins employ a fascinating feeding method called “bubbling.” They will submerge their head underwater and release air bubbles from their feathers. The bubbles then herd and trap fish and invertebrates, making them easier to catch. This takes advantage of the harlequin’s superb underwater vision and diving capabilities.
Here is a table summarizing some of the main fish and invertebrate prey of harlequin ducks:
| Breeding (freshwater) | Wintering (marine) |
|---|---|
| Minnows | Herring |
| Suckers | Sand lance |
| Sculpins | Capelin |
| Trout | Rockfish |
| Salmon eggs | Shrimp |
| Aquatic insects | Crabs |
| Mollusks |
Conclusion
In summary, harlequin ducks do extensively feed on fish as their primary food source. Their unusual breeding habitat on rapidly flowing streams and rivers provides access to a rich supply of freshwater fish. Ducklings learn to dive and feed on fish at just a few weeks old. Then as juveniles and adults, harlequins continue to rely on fish as 50-90% of their diet. When they migrate to coastal marine habitats in winter, they switch to feeding on small saltwater fish along with some invertebrates. So throughout their complex migratory cycle, harlequin ducks can definitively be classified as fish-eating ducks. Their specialized diving and underwater feeding abilities allow them to thrive in these fish-rich environments across North America and northern Europe/Asia.
Related Questions
How do harlequins catch fish underwater?
Harlequins primarily catch fish by swimming and diving underwater. They use their webbed feet for propulsion and their wings to maneuver. They can dive to depths of over 20 meters. Once underwater, their excellent vision allows them to spot fish. They can chase down fast swimming fish. Harlequins also use a unique “bubbling” technique to herd fish.
What adaptations help harlequins catch fish?
– Dense plumage that sheds water and insulates them from the cold water
– Compact hydrodynamic body shape to swim/dive easily
– Strong legs and feet with webbed toes provide propulsion
– Wings help provide lift and maneuverability when submerged
– Excellent underwater vision to see prey
– Serrated edges on bill that help grasp slippery fish
How much fish does a harlequin eat per day?
There are no definitive studies quantifying the exact amount of fish a harlequin duck eats per day. However, we can estimate based on their body size and feeding ecology:
– Average body mass of harlequin ducks is around 550-700g.
– Seaducks need to consume about 10-15% of their body mass in prey each day.
– Feeding rates may be higher during winter when more energy is needed.
– So an estimate is harlequins eat 60-100g of fish/invertebrates per day on average.
– Assuming a diet of 75% fish, they would eat about 45-75g of fish per day.
More research is needed to determine precise daily consumption rates. But they clearly consume large quantities of fish annually.
Threats and Conservation
Despite their impressive diving abilities, harlequin ducks face a number of conservation threats:
– Habitat degradation – Dam construction and resource extraction can alter or destroy river habitats. Coastal development impacts wintering areas.
– Oil spills – Oil spills pose a major risk, especially in marine wintering habitats. Even small amounts of oil can impede waterproofing of feathers.
– Overfishing – Overfishing may deplete food sources, especially herring and other small fish.
– Predation – Nest sites on land are vulnerable to foxes, mink, bears and other predators. Bald eagles may also opportunistically prey on adults.
– Disturbance – Harlequins are sensitive to human disturbance, which can impact nesting and wintering.
– Climate change – Changing water levels, streamflows, ocean conditions, and prey distributions may affect habitat.
Conservation should focus on protecting essential breeding rivers as well as coastal marine habitats. Monitoring and regulating water flows, development, and fishing is also important. Continued research on their ecology and populations will help inform conservation priorities.
Conclusion
Harlequin ducks are fascinating sea ducks that hold a strong reliance on fish as their staple prey. Their unique natural history and habitats allow them to thrive on fish from mountain rivers to northern coastal oceans. But they face an uncertain future due to habitat loss and other threats. Harlequins serve as an indicator species for healthy aquatic ecosystems. Learning more about how harlequins and other sea ducks persist will allow us to better protect our vital marine resources.
