Mules are hybrids of two equine species; the mule's father is a donkey and it's mother is a horse. Mules themselves can be male or female, but they are almost always sterile -- it has something to do with the different number of chromosomes their parents have: horses have 64, donkeys have 62. Mules end up with 63. Pennsylvania farmers breed a large female draft horse like a Belgian or a Percheron with a big male donkey to produce the huge lovely and powerful mules pictured.
We need a special vocabulary to talk about mules. A less commonly successful cross between a male horse and a female donkey produces an animal called a hinny. A male donkey is called a jack. A female donkey is called a jenny or a jennet. Male mules are called horse-mules or jack-mules, but if castrated, john-mules, although that term is sometimes also applied more generally to all male mules. Female mules are called mare-mules. Some female mules have estrus cycles and are called mollies, but that term is sometimes applied to all female mules. On very rare occasions a stallion can impregnate a mollie to produce a hule!
Mules may be sterile but they are not sexless or celibate. They can and do copulate, they just can't make little mules. Aside from not being able to breed, they inherit good traits from both parents. They are strong, smart, patient, surefooted, and beautiful.
|Click to enlarge.
Mules have a reputation for being stubborn. But that may just be a well-developed sense of self-preservation. They will not willingly put themselves in danger and will stop to evaluate new situations before jumping in. And they famously stop dead if an attempt is made to overwork them or get them into trouble. Harry S. Truman said this: "My favorite animal is the mule. He has more horse sense than a horse. He knows when to stop eating -- and he knows when to stop working."
|A donkey. Check out the tail.
It almost never comes up in Brooklyn, but you can tell a mule from a donkey by looking at its tail. A mule tail looks like a horse tail. The donkey's looks like a cow's -- most of it is covered with short hair and it has a tuft at the end, like that thing you used to play pin-the-tail-on-the-donkey with.