What is a "Jerusalem donkey?"

Most donkeys (except for some breeds, such as the Mammoth Jack, which have had it bred out) have a cross on their backs.

It's a pretty legend that the cross was given to the donkey because he carried Christ to Jerusalem - hence the term "Jerusalem donkey."

The "arm" of the cross is clearly visible on the grey donkey in the foreground. Although the black one likely still has the marking, it is not visible against its much darker coat.

Can you put a horse saddle on a mule?

No. Mule and donkey saddles have to be designed a little bit differently because of the shape of their shoulders and withers.

Your characters should not take a saddle off a horse and put it on a mule or vice versa. (Note that the rider won't notice a difference - I've ridden a mule and the saddle felt the same to the rider).

Why are there donkeys here?

When hiking in Switzerland we noticed some very funny looking cows in the pasture:

Yup. Those are standard sized donkeys right in amongst the cows. Are they work animals? Possibly, but a more likely explanation is that they're stock guardians.

Three species are generally used as stock guardians - a more aggressive animal put in with the livestock to deal with predators and other threats (there aren't officially wolves in that part of Switzerland. Officially). Traditionally, dogs were most often used - the Great Pyrenees and Bernese Mountain breeds were both created for this purpose. Dogs have the downside of needing to be fed, however. Modern farmers are more likely to use either donkeys or alpacas, which enjoy the same grass as the animals they're protecting.

What is a burro?

A burro is an ordinary, standard sized donkey in most of the western United States. It's the Spanish for donkey, but expanded beyond Spanish (as did some of the American terms for horse colors). There are some "wild" (feral) burros in the desert southwest. Technically a female burro is a burra, but the word burro is commonly used for both sexes.

Image source Adrian Pingstone via Wikimedia Commons.

What is a zebrass?

A zebrass, zedonk or zedonkey is the cross between a zebra and a donkey.

Unlike with horses, it is possible to breed a zebra hinny (the chromosome numbers are closer together). Additionally, interbreeding between zebras and wild asses, despite the fact that the offspring are not fertile, has been witnessed in parts of Africa where their ranges overlap. It's possible that this may have given people the initial idea to create mules. (Horses and donkeys do not have naturally overlapping ranges).

Like zorses, zedonks resemble the non-zebra parent in body type, but have zebra stripes. Zebrasses have been intentionally bred as work animals, partly in the hope that they would inherit the zebra's resistance to sleeping sickness.

A "zedonk" at Colchester Zoo. Source: sannse via Wikimedia Commons.

What is a hinny?

A mule is the offspring of a male donkey and a female horse.

A hinny is the opposite - bred from a stallion (male horse) on a jennet/jenny (female donkey).

Hinnies are not always possible to distinguish from mules - if in doubt, the animal is referred to as a mule. They're also considerably rarer because it is, for reasons that are presumably to do with the chromosome numbers, much harder to breed the cross successfully. Mule breeders will generally only make a hinny if they really want a particular cross.

Hinnies tend to look a little bit more like horses than mules do. Anecdotally, some muleskinners claim that you can tell whether an animal is a mule or a hinny by turning them out in a field which has a couple of horses and a couple of donkeys in it - a mule will go hang out with the horses and a hinny will seek out the donkeys.

Mule ears. Just because.

What Is A Mule?

I've mentioned mules before, but I just checked and I haven't fully discussed what a mule actually is.

A mule is the offspring of a mare (female horse) and a jack (male donkey).

Mules have long ears like donkeys and full tails like horses, with a build that falls somewhere between the two. They have scraggly manes (which are generally shaved off).

Many people consider mules superior to horses. They live longer (in England, the phrase "donkey's years" for a long time refers to the long lifespan of burros), are more surefooted, eat about one-third less per day and need a lot less water. (I have personally ridden a mule for several hours in a desert environment without watering it, something I would never dream of doing with a horse). They're also less likely to panic and bolt.

However, mules are slower than horses and have a reputation for being stubborn. My personal, limited experience is that mules are less subtle than horses and will really let you know what they think. They don't have a work ethic that will...okay, let's put it bluntly. Horses will tolerate almost anything you do to them. Mules just won't take your crap.

A horse has 64 chromosomes and a donkey 62. Because of this, mules end up with 63 chromosomes. This renders mules sterile. However, john (male) mules are always castrated early as they can be extremely hard to handle otherwise.

Or more accurately, mules are mostly sterile. There have been a few documented instances of molly mules giving birth, with the most famous being Old Beck who produced several foals including Pat Murphy, Jr., who appeared to be pure horse and had normal fertility. Most recently, in 2007, a molly gave birth unexpectedly on a Denver ranch to an animal that resembled a mule.

(To note, some of the reported cases of fertile mollies have turned out to be something else - molly mules are infertile but have normal maternal instincts and equines of all species are notorious for trying to steal other people's foals).

Four saddle mules picketed at Indian Garden in the Grand Canyon. This image doesn't give a good view of their size - the three larger mules are "Missouri mules" which are bred from Belgian mares and American Mammoth Jack stallions (the American Mammoth Jack is an extremely large donkey breed that is related to large donkey breeds found in Spain and France, all of which are perpetuated entirely to breed big mules). The smaller mule on the end is probably from a Quarter Horse mare. The brown and sorrel mules in the center each stand over 16 hands.

Mules are colored similarly to horses, but normally have extreme mealy/pangare, as seen on the sorrel mule. When they lack this, per the brown mule, it's so unusual there's a specific term for it - such mules are called "blue mules."

Why Didn't We Domesticate Zebras?

National Geographic was talking about this today here.

The zebra group (there are several different species) are the only true wild equines remaining with the exception of the endangered Przewalski's horse.

A (quite pregnant) Grevy's Zebra mare. Source: Joachim Huber via Wikimedia Commons.

Zebras can be trained and ridden. Some circuses use them. There's a small market, especially in the US, for "zorses" - zebra/horse crosses, with the idea being that the resulting animal gets pretty zebra stripes and a horse temperament. However, because they are not a domestic species, they are harder to train and more aggressive than horses.

This has led to the myth that zebras were never domesticated because they are "too aggressive." The National Geographic article addresses this quite nicely.

Zebras were simply not the equine species that lived where people in Africa domesticated equines - their range was further south. Instead, they domesticated the ass - the ancestor of the modern domesticated donkey - as northern Africa dried out and cattle herders had to travel longer distances. However, zebras may have given us one thing - it's probable that natural interbreeding that occurs between zebras and wild asses where their ranges overlap gave humans the initial idea behind creating the mule.

An African wild ass. Source pats via Wikimedia Commons.

Asses were domesticated independently of horses but zebras, thanks to geography, escaped that fate.