Jumper serves as the families pack-mule, helping with various work around the farm. When Travis bids farewell to his father, when he leaves to sell their steers on a cattle drive, he is seen riding on Old Jumper. Later on while Travis is using Jumper to help plow in the corn patch, they see Old Yeller chasing a jackrabbit, once Yeller chases the rabbit into the field it spooks Jumper causing him to run. Yeller then begins to chase after Jumper, causing him to wreck the fence (still being hooked up to the plow) as Travis is yelling at the dog to leave his mule alone.
The next day, Travis heads out into the woods with Old Jumper to go deer hunting and Jumper gets spooked by a flock of bobwhites who were nesting in a nearby tree, causing him to throw Travis off his back. Sometime later after getting hog-cut, Kate has Travis pull a hair out of Jumper's tail that she uses to stitch up Old Yeller's injuries and he helps carry them both home to recover. Several days later, Kate, Arliss and Lisbeth are using Jumper to help haul in the corn crop and then sticks to burn the carcass of one their cows who had caught rabies and Jumper is shortly scene running away when Old Yeller is fighting a rabid wolf. Jumper's final scene in the movie is near the very end along side Travis' new horse his father brought home.
Jumper is first scene in the cornfield eating corn, until Arliss shoes him out. Then later while using Jumper to help farm chores, Alriss and Travis see Sam fighting with a bobcat and Alriss quickly mounts Old Jumper as Sam begins to pursue the wild cat. Shortly after Travis and Lisbeth find the three of them, a gang of Apache Indians sho have stollen a whole herd of horses finds and kidnaps them. During the stampede, Jumper tries to get away, but is quickly corralled back into the herd by one of the Indians.
That night, after one of the Indians feeds the kids horse meat Arliss wonders where Jumper is? Travis thinks he's with the horses, but Arliss doesn't see him and thinks that the Indians butchered him. Travis thinks that Jumper might have gotten away, but Arliss didn't see him get away (nor did he see him get butchered) and refuses to eat any part of his families mule. After Travis and Lisabeth convince him to eat, Alriss begins to talk about how much Jumper helped them and now he's keeping them from starving to death. Later on near the end of the film, after returning home they see that Jumpr is alive, Arliss is joyous to see this but at the same time angry with Jumper for being in the corn field once more. As the movie ends Jumper along with Sam and Arliss pursue after the same bobcat from before.