Mallard x Muscovy Duck - Way-out Waterfowl
Mallard x Muscovy Duck hybrids, also known as Mule Ducks or Mulards are large crossbred ducks which have been introduced throughout much of the world. These hybrids usually descend from domestic stock and are released or ‘dumped’ into the wild.
On iNaturalist, many mistake Mule Ducks for different species or vise versa. Most commonly, Mule Ducks are incorrectly labeled as one of its parent species, the Mallard and the Muscovy Duck. In this journal entry, field marks of the Mulard will be discussed. Once you understand how to identify a Mulard, you can help correct IDs.
It’s important to note that hybrid and domestic animals have a lot of variety, so be sure to find multiple field marks before making a positive ID. Not every individual will display every trait. With that said, let’s begin.
Field Marks - What to look for
Caruncles and the Bill
One of the parent species, the Muscovy Duck, is known for its fleshy face. The structures covering the bird’s head are called wattles or masks and are composed of caruncles. This trait is passed down to the Mule Duck but is less pronounced. The caruncles are relegated to the bill base and appear as either lumpy growths or as flat bare skin. They are red and/or black in colour.
Generally, the wattles will appear like they do in the graphic. Juvenile and low wattle Muscovies have less carnacle coverage and can be mistaken for Mule Ducks. Some Mule Duck appear to lack any caruncles. Mallards don’t have caruncles.
The bill of the hybrid can range in colour, from pale, to pink, to grey, to black. The bill can be a single color or have darker markings. Yellow bills aren’t characteristic of the hybrid.
Mulard with visible caruncles at the bill base. Bill is a grey tone with darker accents.
Plumage and Feathers
The plumage of Mulards is very variable with many colors and patterns being possible. Much of the time, their plumage is made up of blacks, whites, greys, and/or browns. Commercial Mulards have all-white plumage.
Interestingly, the green sheen from the Muscovy Duck’s feathers consistently makes an appearance, most commonly in the speculum and head, though it's not always present. It should also be noted that Mallard breeds such as the Cayuga also have a green sheen to their feathers, so avoid using this trait alone as a sure-fire way to ID a Mule Duck.
As for the structures of the feathers themselves, they seem to take after Muscovy once again. The feathers on the wings are large and ovalular while the tail feathers are long, flat, and erect (this can be especially noticeable in the water). Some Mule Ducks have even shown themselves to have a Muscovy-like crest on their head, though less prominent.
Mallard signatures, such as chestnut breasts, thick white neck rings, and heads of a separate colour from the body often occur. More female-like traits such as facial stripes too.
Body Structure
The body of the hybrid is more like a Muscovy’s, having a long rear, short thick legs, wide feet, and more pronounced claws. Most Mulards are also extremely large and bulky and males are mentioned to be larger than females.
While unconfirmed, curled tail feathers appear to be greatly reduced or even absent in Mule Ducks. In any case, this trait is much more visible in male Mallards.
Additional Information
Conception and Reproduction
A Mallard-Muscovy pairing actually has a low chance of producing a hybrid naturally, so farmers often use artificial insemination. Because of this, most Mule Ducks encountered are likely to be of domestic origin.
The hybrid of a Mallard-Muscovy pairing will be built differently depending on which parent was which species. A male Muscovy paired with a female Mallard will produce a Mule Duck while a male Mallard and female Muscovy pairing will result in a Hinny. Of the two, Mule Ducks are larger and are used in the commercial meat industry. Hinnies are smaller and the less common form of the hybrid.
Generally, Mule Ducks and Hinnies are sterile and can’t produce offspring of their own. Because of this, most, if not all Mallard x Muscovy Ducks are first-generation hybrids (F1).
Use in the Meat Industry
Mulards are bred for meat and Foie Gras production with males and females serving different purposes. Because they’re hardier, males are used to produce Foie Gras, a French delicacy which involves force-feeding the duck to expand its liver. This process is known as gavage.
Female Mulards are raised for their large breasts as their livers can’t withstand gavage.
Mule Ducks in the meat industry are pure white so once the body is plucked of feathers, no black marks are left on the meat.
Gallery
A very dark Mule Duck. Note the green sheen on the wing feathers, long tail feathers, and its overall shape. No visible caruncles however.
Size comparison between Mulard and wild Mallard.
Two Mulards, possibly a male and female pair. The observer mentioned that they flew. They have orange legs.
A male Muscovy Duck and (possible) female Mule Duck are seen courting together. Both appear to be wild-types.
A female Mulard, nicknamed Maynard, was able to construct a nest by a pond. She is noted to be very friendly and regularly interacts with the pond’s other inhabitants.
View all of iNaturalist’s RG Mule Duck observations. Again, please don’t spam IDs.
https://inaturalist.ca/observations/identify?reviewed=any&quality_grade=research&taxon_id=326092&place_id=any
ID Sum-up
Mule Ducks are defined by caruncles at the bill base, a pink bill, and long tail feathers. Other features such as green wing feathers and a Muscovy-like body shape can also be used but with more caution.
Note that certain domestic Mallards and Muscovies can resemble Mule Ducks.
Credits
Thank you to @liliumtbn and @rlhardin for reviewing this journal post and suggesting edits. My gratitude also goes out to the identifiers of this hybrid as well.
Photo Credits
A big thanks goes out to those who contributed photos to this journal. Photos are credited in the order they appear. (Please don’t spam IDs)
@chalon9. “Mallard × Muscovy Duck”, April 5, 2021.
https://inaturalist.ca/observations/73082973
@westernpawildlife. “Mallard × Muscovy Duck”, February 27, 2022.
https://inaturalist.ca/observations/107701735
@merlu. “Mallard × Muscovy Duck”, August 11, 2020.
https://inaturalist.ca/observations/56170476
@jessica_peruzzo. “Mallard × Muscovy Duck”, April 1, 2018.
https://inaturalist.ca/observations/18453134
@americanmamushi. “Mallard × Muscovy Duck”, March 2022.
https://inaturalist.ca/observations/108023140
@mariourrutia. “Mallard × Muscovy Duck”, April 8, 2003.
https://inaturalist.ca/observations/67549416
@annalanigan. “Mallard × Muscovy Duck”, October 20, 2020.
https://inaturalist.ca/observations/63380263
@oliverkomar. “Mallard × Muscovy Duck”, October 4, 2020.
https://inaturalist.ca/observations/61750949
@pinemartyn. “ “Mallard × Muscovy Duck”, December 10, 2017.
https://inaturalist.ca/observations/9179413
@terranova. “Mallard × Muscovy Duck”, Feb 5, 2022,
https://inaturalist.ca/observations/106338578
@lizholland. “Mallard × Muscovy Duck”, June 20, 2022.
https://inaturalist.ca/observations/126496548
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https://animalequality.org/blog/2022/02/08/what-is-foie-gras/
Zero G Ducks. “Mulius - A Duck / Muscovy Hybrid”, Youtube, February 3, 2022, accessed August 10, 2022.
https://www.youtube.com/watch?v=M1ysK7BoL9s
Poultry Industry. “Ducks World”, Engormix, December 14, 2017, accessed July 19, 2022.
https://en.engormix.com/poultry-industry/articles/ducks-world-t41031.htm
Cornell University. “Domestic Ducks”, Cornell University, 2016, accessed October 14, 2022
https://www.vet.cornell.edu/animal-health-diagnostic-center/programs/duck-research-lab/domestic-ducks
Dave Appleton. “Muscovy Duck x Mallard”, Bird Hybrids, March 7, 2014, accessed May 22, 2022.
http://birdhybrids.blogspot.com/2014/03/muscovy-duck-x-mallard.html
Ducks and Clucks. “All About Caruncles” Duck and Clucks, January 4, 2013, accessed June 29, 2022.
https://ducksandclucks.com/blog/2013/01/04/all-about-caruncles/
Dr. Ed Hoffmann. “Mule Duck | aka Mullard, Barbary Duck”, Feathersite, December 1993, accessed January 2022.
http://www.feathersite.com/Poultry/Ducks/Musc/Mule.html
R. H. Rigdon and Charles Mott. “Testis in the Sterile Hybrid Duck" | A Histologic and Histochemical Study”, Department of Pathology, University of Texas Medical Branch, 1965, accessed Jul 14, 2022.
https://journals.sagepub.com/doi/pdf/10.1177/030098586500200603
