Stubborn as a Donkey?

—Alex, via e-mail

A.That is great topic. In fact, one of my most well-used and favorite teaching slide sets is entitled Donkeys are Not Horses. I first assembled it to outline and explain the biological basis of the many differences in donkeys’ social and reproductive behavior. I and my colleagues learned early on that if you try to breed donkeys as you would horses, things often don’t progress very well. That led to studying free-roaming donkeys in Brazil. I still remember the embarrassing moment when I realized how silly it was of me not to have figured it out sooner. These species’ behavior is in fact very different for very good evolutionary reasons. Over the years my interest and the slide set have grown to include other differences than reproductive that can be equally confusing and frustrating.

Many of the behavior differences stem from differences in how the various equid species evolved. Donkeys and asses and Grevy’s zebras that evolved mostly in arid regions where forage and water were sparse naturally have a primarily territorial social organization and system of breeding. In contrast, horses (e.g., Przewalski’s horse and the common zebra) evolved in environments favoring a social herd organization. Horse herds are composed of multiple harem bands of one mature stallion, multiple mares, and their juvenile offspring, as well as bachelor bands of mostly or all males of various ages. Harem stallions herd and guard their families, staying with them at all times, but they also maintain relationships with other bands in the herd, such that they share defense of the herd as a whole in times of major threats.  

In the territorial system each breeding male lives alone, guarding a territory of land rather than a group of females. A breeding male (jack) gains access to females (jennies) by having a resource-rich territory that attracts females, increasing the odds that when a female is in estrus she will be in his territory. That typical jack braying vocalization every hour or so is the jack’s way of calling out over the distance of his territory to draw closer any jennies that may be in estrus. The females wander in and out of various males’ territories more or less as solitary adults along with any dependent young. The donkeys within an area likely “know” each other, but because resources are typically scarce, they do not assemble in groups and the jennies don’t have the ongoing protection of males. 

Many of the differences we appreciate in the behavior of our domestic donkeys and horses are attributable to this solitary versus group social organization. When threatened, horses that evolved in herds, where there is safety in numbers, tend to come together and to move off together following the lead of one or more sentinel animals, much like a flock of birds or a school of fish. Stallions, mares, and bachelors have specific roles in protecting the herd and the young. This tendency is the basis for separation stress or the “herd-bound” horse. Our domestic donkeys generally don’t come together in times of threat and so appear to be more independent within a pasture group than horses. A donkey that is pastured with horses is more likely to be off on its own most of the time (but not always) and is likely to be the first animal to approach a threat—again, on its own. This is why property owners often use donkeys as guard animals.  

For horse herds, the bachelor band is an “army” of sorts—the herd’s first line of defense. Mares rarely have to fight. In contrast, both male and female donkeys must protect themselves alone, and jennies must also protect their dependent juveniles. So all donkeys, both male and female, tend to be fiercer fighters and quicker to fight when cornered than horses. Solitary animals also tend to be quicker to freeze and to “survey the situation” when fearful, which is why donkeys seem to have a greater fear of being trapped than horses. This is why donkeys struggle more than horses with loading for transport or learning to lead in and out of confined spaces.  

Another tendency of solitary species is to hide, and donkeys’ coats can effectively serve as camouflage. Whenever threatened, burros tend to linger near or under foliage and are difficult to spot. Without a large group’s help to detect danger, solitary animals also have to be especially perceptive, and they notice everything. They are also very quick to adapt their behavior due to experience. In other words, they are quick at associative learning, and learning is accelerated in the face of fear. As prey species, all equids have evolved to show little change in behavior with fear, pain, or debilitation. The solitary species are the extreme of this stoicism. This is a huge welfare issue for donkeys, as they can be near death or in extreme pain without easily recognized behavior changes.

These characteristics of donkeys can be so confusing to horse people. For example, when the donkey is afraid and puts on the brakes, yet doesn’t appear to its handlers as fearful, his behavior is easily misinterpreted as “stubborn.” People then often resort to physical means of pushing or goading to try to get the donkey where they want it to be. It is easy to go to extremes, into the range of abusive physical means, since the animal shows only subtle signs of discomfort. And it doesn’t help that when the poor thing finally can’t take any more, it explodes aggressively without warning.

Similarly, fearful donkeys seem to learn much faster than typical horses that they are strong and wiry enough to barge over us to escape negative pressure. We easily make the mistake of thinking they are “stupid.” This is especially the case when we don’t recognize a donkey’s fear. The truth is that the donkey is likely learning much faster than a horse, but our usual teaching methods are not good enough, and we are inadvertently applying repeated pressure and release, teaching that escape behavior. This is why donkeys are great for demonstrating the use of positive methods to shape the behavior we want. If you stay away from all negative interactions that can provoke fear, you can see immediately how much faster donkeys make associations than the typical horse, and it doesn’t take long before you can train your eye to recognize the subtle signs of fear and pain versus positive motivational states in donkeys.