Stubborn, obstinate, headstrong — all words that have been used to describe mules. And calling someone “mulish” or “muleheaded” has never been intended as a compliment. Mules have a reputation for being difficult to work with. Stories abound about mules simply refusing to work for their owners. It’s easy to regard such stories as evidence of mules’ unwillingness and laziness, but the truth is much more complicated.
What exactly is a mule? A mule is a cross between a donkey and a horse — more specifically, a male donkey and a female horse. (A hinny is a cross between a male horse and a female donkey.) Horses have 64 chromosomes and donkeys have 62. The mule and the hinny both have 63, an odd number that renders them sterile — in the majority of cases. There are never any absolutes in nature, and there’s a handful of documented cases of mules giving birth to healthy offspring.
Mules and their donkey and horse parents share a lot of similarities, but also several key differences. Mules tend to have smaller feet than comparatively sized horses. This gives them a distinct advantage when walking between rows of crops or down steep mountain trails. The donkey has a steeper pelvic angle than the horse, and this is passed down to mule offspring. Mules also have shallower withers, which makes a well-fitted riding saddle or pack rig a must.
Why the Long Ears?
Donkeys evolved in hot, arid climates, where their long ears help with heat radiation. Mules have those same long ears, which are very sensitive and contain many blood vessels.
As a result of their desert evolution, donkeys came to be able to use minimal forage very efficiently; the mule retains this feed efficiency too. It doesn’t take much overfeeding for a donkey to become fat. Mules have a much smaller appetite than horses, and seem to have the ability to better self-regulate their feed intake. A horse leaving food, on the other hand, would be a cause for alarm. That’s not to say mules’ feed intake shouldn’t be carefully monitored, but do keep an eye out for other symptoms of “off” behavior in your mule. Mules are also much less prone to colic than horses, and are able to adapt to whatever forage might be available, even if it’s something they wouldn’t normally eat. Mule feet are much harder than those of the horse, which, combined with their uncanny surefootedness, makes them desirable for working in rocky terrain.
Mules have a smoother musculature than a horse, but pound for pound they’re considered to be the stronger animal. Mules also have more stamina than horses, and can maintain a steady walking pace for an entire workday. Depending on how well the load is packed and how much it moves, a trained and fit pack mule can carry between 20 and 35 percent of its body weight. A load that moves around too much will require the mule to work harder to stay balanced and keep the load stabilized.
While there are only a handful of recognized donkey breeds, such as the Mammoth Jackstock and the Poitou, donkeys tend to be defined more by type or size. The mule is often referred to by the mare parent’s breed: The offspring of a Mammoth Jack and a Belgian mare would be called a Belgian mule, for example.
Mules are intelligent, and that intelligence combined with their healthy sense of self-preservation leads to their reputation for stubbornness. A horse can be bullied and intimidated into doing what you want; a mule cannot. You might get them to go along with you in the moment, but they won’t forgive and forget like a horse.
Mules want a fair, confident leader, and once a mule respects and trusts you, it’ll be a willing partner. They thrive on routine, which is why mules can be such trustworthy pack animals. They willingly follow the leader, often without being tied or led. A mule that’s accustomed to his job, such as plowing a familiar field, could theoretically be left to his own devices to complete the job.
Mules have been deliberately bred for centuries. Evidence of their utility dates back to ancient times, and they were, in many cases, considered more valuable than their horse and donkey counterparts.
George Washington is considered the “father of the American mule,” and is credited with popularizing mules in the United States. Convinced of the mule’s superiority as a draft animal, and impressed by the quality of European donkeys and mules, Washington wrote to King Charles III of Spain, hoping to purchase some of the famous Andalusian donkeys. At the time, Spain was so fiercely proud and protective of these donkeys that it was prohibited to sell any outside the country without the king’s permission.
King Charles instead sent a jack (donkey) to Washington as a gift. The jack, appropriately named “Royal Gift,” was the basis for the mules that would revolutionize draft power in the United States. With the addition of a Maltese jack gifted to Washington by the Marquis de Lafayette, the offspring of these two breeds became very valuable and highly sought-after breeding stock. Washington’s donkey stock eventually became the basis for the creation of the American Mammoth Jackstock, a breed of donkey well-known in the day for producing fine draft mules.
Mules quickly became the draft animal of choice in the South, where their heat tolerance, small appetite, capacity for work, and small feet gave them an edge in planting and harvesting crops.
Mules led the way west in the early 19th century. Trains of pack mules crossed rocky, dangerous trails on a regular basis, bringing goods from one side of a mountain range to the other. The mules that pulled settlers’ wagons also helped build their houses and plow their fields. Choosing a mule companion was a serious and important decision. A good mule could mean the difference between success and failure, and in some cases, between life and death.
One of the best-known mule teams in U.S. history was the 20-mule hitch that hauled borax out of the mines in Death Valley in the 1880s. Two teams, totaling 18 mules and two horses, were hitched to a wagon, forming a massive 100-foot-long train. There was no water along the path, so mule teams had to carry their own water on the trip. The combined weight of the heavy wagon, water, and borax was 36 tons. The 165-mile trip took 10 days one way, and traversed some pretty grueling terrain in temperatures reaching upward of 130 degrees Fahrenheit at times.
Turning and maneuvering such a long train required serious coordination. As the train of mules turned, the mules in the middle of the line would have to jump over the tow chain to avoid getting tangled or bumped as the wagon moved. Each pair of mules had a specific role in the complex turning process, and a specific moment at which to make its move; if the timing was off, it could cause serious injury.
In the six years the 20-mule teams were used — before they were replaced by a railroad — it’s estimated that they pulled some 20 million pounds of borax out of the desert. Not a single mule was lost during that time, a true testament to their hardiness. The 20 Mule Team trademark was first used in 1891, and remains on every box of 20 Mule Team borax today.
Mules in the Military
No discussion of the mule’s service to mankind is complete without the history of its military service. Mules were used extensively during the Civil War and World War I to move supplies and equipment, but at the onset of World War II, the military began to replace the sturdy pack mule with vehicles. However, they quickly learned that the mule’s ability to thrive on lesser quantity and quality forage, as well as the animal’s talent for crossing rugged terrain, made it indispensable. Mules were even able to survive on unusual food, such as bamboo leaves and other locally available forage.
In 1956, the last Army units of mules were officially deactivated. But they were brought back to serve in Afghanistan in the 1980s, as mules could go places motorized vehicles couldn’t access. In 2001, mules were used to support the efforts of the famous Special Forces “horse soldiers” by carrying supplies and munitions.
The Army still maintains mules, and, in 2004, published a manual detailing the care and selection of pack animals, extolling the virtues of the mule for its steadiness, intelligence, and ability to navigate difficult terrain. While modern technology means there have been efforts to create robotic transport devices that can mimic the careful steps of the mule, those devices are very expensive and come nowhere near replacing the mule’s natural abilities and instinct. And they’re probably less enjoyable for the soldiers to work with.
Mules still play a significant role in other niches today. Even though tractors and mechanization are widely available, some people prefer using draft animals for reasons such as having a lesser environmental impact, less dependence on fossil fuels, and the simple enjoyment of working closely alongside another living being.
Mules are also used to assist firefighting efforts in remote and inaccessible areas. In some locations, environmental regulations and rugged terrain make vehicle transport unrealistic. Pack mules can carry loads of supplies to firefighters working in otherwise unreachable locations.
Pack mules are also indispensable to hunters packing people, supplies, and equipment into remote hunting areas. A well-trained mule won’t balk or protest at an elk carcass, or whatever the quarry of the day is. Many hunters prefer mules exclusively, claiming they won’t tangle lines or bump loads (or knees!) against trees, and their steady pace keeps things from getting jostled around too much.
Mules have also been described as straightforward, patient, and surefooted. One thing’s for sure: much of our history would’ve been written very differently without the steadfast mule. So, if anyone ever calls you mulish, give them a hearty thanks.
By day, Callene Rapp is a senior zookeeper, where she’s learned to manage all sorts of animals at the Sedgwick County Zoo in Wichita, Kansas. By night, she manages The Rare Hare Barn with her husband, Eric.