The Harlequin Duck (Histrionicus histrionicus) is a small sea duck known for its striking and complex plumage patterns. The male and female Harlequin Duck have very different plumage that changes over the course of the year. Here we will explore the fascinating details of Harlequin Duck plumage and what gives this species its distinctive appearance.
Plumage of the Male Harlequin Duck
The breeding plumage of the male Harlequin Duck is exceptionally colorful and ornate. The most striking feature is the slate blue coloration on the sides of the head, neck, breast, and back. Interspersed throughout the blue plumage are round white spottings or streaks. Two black stripes run vertically down the back of the neck. The crown and nape area is black, while the sides of the head have large white patches. On the flanks are rectangular grey-blue patches called “hand mirrors” that are bordered with chestnut. The speculum feathers on the wings are iridescent sea-green bordered with black and white bars. The tail is grey-blue. The belly and undertail coverts are white. The bill is blue-grey with a black nail and the eyes are reddish-brown. The legs and feet are bluish-grey.
This bold breeding plumage likely helps male Harlequin Ducks attract mates and defend breeding territories. The striking colors and patterns make males highly visible during courtship displays on fast moving streams. The complex plumage may also communicate important information about fitness to prospective mates.
Plumage of the Female Harlequin Duck
Female Harlequin Ducks have a much more subdued plumage compared to males. Their overall coloration is various shades of brown, black, and grey. The head and neck area is chocolate brown. The sides of the head have a faint white patch that is less defined than in males. The breast, flanks, belly and tail coverts are grey-brown. There is fine vertical white barring on the flanks. The back and wings are dark grey-brown. Like males, females have iridescent sea-green speculum feathers edged with white and black bars. The eyes are brown, the bill is slate-grey, and the legs and feet are bluish-grey.
The drab female plumage provides camouflage while nesting and rearing ducklings. The cryptic shades of brown, black and grey help females avoid detection by predators. This allows them to protect the nest site and ducklings when the brightly colored males have departed to their molting grounds.
Male Non-Breeding (Basic) Plumage
After breeding, male Harlequins undergo a complete molt into a dull basic plumage. This non-breeding appearance resembles a female, but with some key differences. Males retain the faint white facial patches, the vertical neck stripes, and brighter legs. But overall, the slate blue breeding plumage is replaced by mottled greys, browns, and blacks. This cryptic non-breeding coloration provides better camouflage from predators during the flightless wing molt period.
By late winter, males will begin transitioning back into breeding plumage through a partial molt. They replace body feathers while retaining their flight feathers. By spring, males are once again sporting their showy breeding apparel.
Eclipse Plumage in Males
Some male sea ducks, including Harlequins, may temporarily take on an eclipse plumage that resembles female coloration. Eclipse plumage occurs after breeding while flight feathers are being replaced. Males in eclipse plumage have female-like grey-brown colors but retain the white facial patches. Not all males will eclipse, and those that do only remain in this transitional plumage for several weeks before returning to the typical non-breeding basic appearance.
Juvenile Plumage
Hatchling Harlequin Ducks have downy black, brown, and yellow plumage. After fledging, juveniles take on plumage similar to adult females but with some distinct differences. Juveniles have pale grey-brown overall coloration. The sides of the head and the belly are paler than adults. The flank feathers lack the fine white barring. The tertial wing feathers are edged with rusty brown. The bill of young birds is darker grey. Juveniles will hold this plumage through their first winter before transitioning to adult-like plumage.
Molts and Plumage Cycles
Harlequin Ducks have complex molting cycles that allow them to transition between striking breeding plumage and dull non-breeding plumage. Males have two molts per year while females only molt once. The following summarizes the molting patterns and plumage cycles:
Male Harlequin Duck
- Late Winter Partial Molt – Males transition back to breeding plumage by replacing body feathers while retaining old flight feathers.
- Spring/Summer – Males in bright breeding plumage
- Late Summer Complete Molt – Males lose all feathers and take on dull basic non-breeding plumage.
- Fall/Winter – Males in cryptic basic plumage.
- Late Winter Partial Molt – Cycle repeats back to breeding plumage.
Female Harlequin Duck
- Late Summer Complete Molt – Females molt all feathers and take on fresh plumage.
- Fall/Winter – Females retain same plumage year-round.
- Late Summer – Cycle repeats with another complete molt.
| Season | Male Plumage | Female Plumage |
|---|---|---|
| Spring/Summer | Breeding | Basic |
| Fall/Winter | Basic | Basic |
Conclusion
The striking breeding plumage of male Harlequin Ducks and the more subdued female plumage provide excellent examples of how feather patterns and colors can be adapted for specific functions. The dazzling colors of male breeding dress likely serve to attract mates and advertise vigor. Meanwhile, the cryptic shades of females help conceal the ducks and their nests during breeding duties. By undergoing an annual cycle of molts, Harlequins transition between plumages that are carefully attuned to the seasonal demands of courtship, nesting, and feather regeneration.
