Among the summer mammals, the elk is one of the largest yet least viewed. A herd of about 150 bases itself near Union Peak and grazes in the meadows on the south side of the park. Elk are most common in open areas near timber stands, where they graze on grasses and shrubs. They stand up to five feet high at the shoulder and can weigh up to six hundred pounds. Despite their size, elk have an uncanny ability to move quietly and avoid detection.

One of the year round residents, the pine marten, becomes especially active in the winter. The hunt for food keeps them on the move and their lack of natural predators allows them to be especially brave. The pine marten is a close relative of the short-tailed weasel, and is distinguishable from its cousin as the marten keeps its brown coat throughout the year. This is due in part to the lack of predators the pine marten has during the cold, snowy months. Pine martens have adapted themselves especially well to survive this time. Their small bodies and large feet allow them to bound over the snow very effectively in their hunt for food, most notably mice and other small rodents.

All animals in the park are wild and management policies discourage animals' dependence on human food. Taming wildlife is undesirable as it creates an environment where wildlife becomes a sideshow. Even worse, when animals depend on humans for food, they lose their independence. Once the seasonal visitors depart, the animals suffer because they are no longer accustomed to finding food for themselves. All animals in the park are wild, and as such, they may indeed bite the hand that feeds them. Wild animals also carry diseases which can be transmitted through simple contact. So, feeding animals is not only to protect an animal's independence, but to protect people as well.