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Mule vs. Donkey: Similarities And Differences Explained

The mules and donkeys sometimes closely resemble each other. So much so that people often assume they are the same animal. 

We may use their names interchangeably; the famous saying “as stubborn as a mule/donkey” is a good example. However, a donkey differs from a mule, although they share many behavioral and physical characteristics. 

In this article, we make an interesting comparison of the mule and donkey.

What is a donkey?

donkey on grass
Donkey, Photo by TS Sergey on Unsplash.

A donkey is a hoofed mammal. They belong to the same family as the Equidae horse but are a separate species. Donkeys were first domesticated in Africa over 4000 years ago. They are descendants of the African wild ass.

A male donkey is called Jack, while a female donkey is called Jenny or, less commonly, Jennet. A male donkey is also called a jackass; that's a combination of two words, Jack and ass. Burro is another popular Spanish word for donkey. 

What is a mule?

brown mule
Mule, Photo by Don Graham on Wikimedia Commons licensed under CC BY-SA 2.0 (Cropped from original).

A mule is the hybrid offspring of a male donkey and a female horse. It has existed for at least 3,000 years and is still common in many parts of the world. Mules are not considered a species on their own, but they do have a scientific name: Equus mulus.

We refer to a male mule as a John mule, also called a horse mule or Jack mule. We call the female mule a Molly mule or mare mule. A young female mule is a filly, while a young male mule is called a colt. 

What are the differences in characteristics between mules and donkeys?

Members of two different species, the male donkey and the female horse, come together to produce a mule. Therefore, we can expect mules to share some characteristics with both the horse mother and donkey father. Mules have so much in common with their donkey parent, as well as many distinguishing traits. We look at some below.  

1. Coat

brown mule
Mule, Photo by Leon Woods on Pexels.

A donkey's coat can be gray, brown, or black. There are also rare colors like white and roan. Their coat has short hair and a coarse texture. Donkeys typically have a short mane and a distinctive dark stripe running from their head all along their spine. They have another dark stripe across the shoulders.

Mules usually inherit their coat color from their horse parents, so their coats vary greatly. You'll find mules with palomino, buckskin, tan, roan coats, and black coats. A mule’s coat has a finer and thicker texture compared to a donkey's, but it is not as thick as that of horses. A mule also has a short mane like a donkey but lacks the dark dorsal stripe. 

2. Size or height

Compared to horses, donkeys are much smaller. The average donkey measures about 40 inches from the shoulder. Even the largest donkey, the American Mammoth Jackstock, stands at 56 inches from the shoulder to the front hooves.

Mules are significantly larger than donkeys but smaller than horses. They get their large size from their horse mothers. Most mules stand an average of 50 to 70 inches tall from their shoulders to hooves. 

3. Shape

A donkey has a short, thick head, a compact body with a flat back, and thin limbs. Its narrow, oval hooves make it easier for it to travel across rocky terrains.

A mule also has a short, thick head, thin legs, and narrow hooves. The hooves are wider and rounder than those of a donkey. The mule’s back is slightly curved like a horse's but not quite as pronounced. 

4. Ears

donkey ears
Donkey, Photo by Laura Nyhuis on Unsplash.

Donkeys have very long, thick, and wide ears. These ears can pick up sounds from great distances, which is useful as it allows them to forage as a group, covering a large area in their arid habitat. Beyond that, donkey ears help to regulate their body temperature. 

A donkey has longer ears compared to a mule. Although the mule’s ears are shaped like horse ears, they have longer ears than those of horses. Like donkeys, mules have exceptional hearing. Their sense of touch is also strong, they can feel vibrations of movement from far away. 

5. Tails

Donkeys and horses have very different tails. The donkey's tail is long and thin, with a tuft of short hair on the end, resembling a cow's tail. A horse's tail has long strands of hair flowing from the tailbone to the tip. 

A mule has a horse-like tail, with long, coarse hair growing from the tailbone. Mules can easily flick their tails around their rump and sides to get rid of pesky flies.

6. Sounds

two mules
Mule, Photo by Kevin Degirmenci on Wikimedia Commons licensed under CC BY 3.0 (Cropped from original).

Donkeys make braying, "hee-haw” sounds to communicate. Each donkey’s style of braying is unique but the braying sound is usually quite the loudest sound donkeys can produce. You can listen to a donkey's bray here.

Most mules produce a sound similar to a horse’s whinny that ends with braying. You can listen to the mule's call here. Mules may also whimper when worried or excited.

7. Reproduction

Female and male donkeys can reproduce, just like horses. However, mules are generally sterile and cannot produce offspring. That's because they are hybrid animals with 63 chromosomes, midway between the 62 of the donkey and 64 of the horse. Chromosomes need to pair up evenly for the fertilization to occur.

Female mules may or may not go through estrus, while uncastrated males can mate. In rare cases, a female mule can be fertile and mate with a male horse or donkey to reproduce. Sometimes, an embryo is implanted directly in the womb of female mules. However, in all cases, male mules are entirely sterile.

8. Temperament

donkey on farm
Donkey, Photo by Kevinsphotos on Pixabay.

Donkeys get a bad rap for being stubborn. However, they only have the common sense to hesitate when they sense potential danger. They are, however, stoic and won't startle or show signs of tiredness easily. Sometimes, donkeys drop dead from exhaustion without showing signs.

Mules are mild-tempered animals, and male mules are usually castrated to make them even calmer. However, they have a strong sense of self-preservation, which may come across as stubbornness. A mule will show signs of pain less often than a horse and more often than a donkey.

9. Intelligence

Studies have proven both donkeys and mules to be smart1. Donkeys, often misrepresented cognitively, exhibit a substantial heritable element of intelligence, with genes interacting similarly to humans. Upon testing, researchers found that intelligence can explain roughly 62% of their cognitive variance. 

On the other hand, mules outperformed both donkeys and ponies in a visual discrimination learning task2. More studies are still needed to explore the intelligence of these equines.

10. Strength

mule on field
Photo by Georgia Reading on Flickr licensed under CC BY 2.0 (Cropped from original).

Donkeys have been used as beasts of burden for thousands of years. They can carry heavy loads across rough terrains over long distances. The strength of horses lies in their ability to run faster and jump over obstacles easier than donkeys ever could. 

Mules are much stronger than donkeys and are more hardy than horses. They can carry more weight and move faster than donkeys. Mules can also jump over or across obstacles from a standing position. They are as sure-footed as donkeys.

11. Diet

donkeys eating grass
Donkey, Photo by Mark Stebnicki on Pexels.

Donkeys evolved in arid regions where food was scarce so they are conditioned to survive on rough shrubs, low-nutrition grass, and tree matter. Horses on the other hand require a highly nutritious diet from lush grass, fruits, and so on.

The dietary needs of donkeys and mules are quite similar. They require hay with low nutritional value. Their digestive system is adapted to work slowly and thoroughly to extract every nutrient from their food. That's why they can easily exceed a healthy body weight if they eat what a horse would. The wrong kind of food can also cause mules to become ill.

What is a hinny? 

hinny
Photo by Ragesoss on Wikimedia Commons licensed under CC BY-SA 4.0 (Cropped from original).

When a male horse mates with a female donkey, their offspring is called a hinny. The name is likely pulled from the word horse and the name of a female donkey, Jenny. Hinnies are not as common as mules.

The main difference between a hinny and a mule is size. Mules tend to be much larger than Hinnys. The suggested reason is that the womb of the donkey's mother is much smaller than that of a female horse.

Hinnies have a more donkey-like temperament because the donkey mother typically raises them. 

Why do people breed mules?

When cross-breeding occurs between two species, something called hybrid vigor occurs. This allows the hybrid to get the best traits from its parents and eliminates the continuation of unfavorable genetics.

The mule gets the best physical characteristics of both a donkey and a horse. That means it provides the most value for people who rely on equids for labor in places such as Afghanistan, Africa, and Egypt.

A mule is a better pack animal than a donkey because it's faster and stronger. Mule hooves are also well adapted to rocky, hot, dry terrains; they don't require as much care as horse hooves. They are bigger than donkeys and can quickly jump over obstacles on the travel path.

Additionally, mules are not picky eaters, and food takes longer to work its way through their digestive system. They are more adaptable to colder climates than donkeys because their coats grow thicker in the winter. 

Mules are also great for leisure riding, thanks to their calm nature. They are also easier to train than horses. 

Donkeys live for an average of 47 to 50 years, and mules live almost as long, with an average of 30 to 40 years. They have a longer lifespan than horses. Note that hard labor and lack of access to veterinary care can significantly shorten a mule's lifespan.

Conclusion: Mule vs. Donkey

Donkeys and mules share many similar physical traits but are not the same animal. A donkey is a defined species, but a mule is a product of interspecies reproduction between a male donkey (Jack) and a female horse (Mare). 

Even though they can't reproduce, mules are so popular. They have greater stamina than either of their parents, and they are also quite easy to look after.

1

González, F. J. N., Palomino, J. V., Jurado, J. M. L., McLean, A., & Bermejo, J. V. D. (2019). Dumb or smart asses? Donkey’s (Equus asinus) cognitive capabilities share the heritability and variation patterns of human’s (Homo sapiens) cognitive capabilities. Journal of Veterinary Behavior, 33, 63–74.

2

Proops, L., Burden, F., & Osthaus, B. (2008). Mule cognition: a case of hybrid vigour? Animal Cognition, 12(1), 75–84.

Jen’s a passionate environmentalist and sustainability expert. With a science degree from Babcock University Jen loves applying her research skills to craft editorial that connects with our global changemaker and readership audiences centered around topics including zero waste, sustainability, climate change, and biodiversity.

Elsewhere Jen’s interests include the role that future technology and data have in helping us solve some of the planet’s biggest challenges.

Fact Checked By:
Isabela Sedano, BEng.

Donkey, Photo by David Selbert on Pexels and Mule, Photo by John on Flickr licensed under CC BY-SA 2.0 (Cropped from original).
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