I did a lot of research for my frontier novel, Detour Trail, including the history of the Oregon Trail; and I learned a lot about mules too because one of my main characters is a mule named Jake, who helps my heroine, Lorrie, along the way. One of my first sources said that mules were mostly black so I made Jake black 'cause I wanted to be accurate. Later I learned--and I have the pictures to prove it on my Western Style board on Pinterest--that they could be the same colors as horses. After all that's in their genes! On the other hand, making him too splashy might detract from the story. Hmm. I wonder what readers would think?
I also learned that mules are smart, good jumpers, and can do just about anything a horse can do. And they have their own magazines and celebrations. (See my Pinterest board for a few examples.) However, I suspect that Jake is a bit mythical, but I like that in a character. Lorrie can count on him, and her friends, when trouble looms on the trail. From ambushes and blizzards to building and working and starting a settlement, Lorrie, Jake, and her companions move steadily forward to forge a new future in the west.
Note: I read The Oregon Trail: An American Journey by Rinker Buck since I'm interested in the history of the trails--The Oregon Trail is not just one trail, by the way. I was truly surprised by the fact that one of Buck's three mules was named Jake, and he was the most trustworthy and even tempered of the three. I recommend Buck's book both for the history included in it and as a modern day adventure.
The Oregon Trail an American Journey
My Western Style board