Most of the vertebrate species found in fell ecosystems are the same as the ones encountered in coniferous forests. As the elevation of the fell increases, coniferous forests give way to mountain birch forests and finally to bare fell summits. These environments accommodate their own species.

The low vegetation found on fell summits is beneficial for rodents, such as voles. The rodent species best adapted to the harsh conditions of the fells is the Norway lemming.

Norway lemmings can be found on fell slopes.

The Arctic fox is a predator that is specialized in hunting fell-dwelling rodents. However, the population of Arctic foxes has decreased rapidly during the course of the last few centuries, and the species is now considered critically endangered. Aside from reindeer, other large mammal species are hard to find in fell ecosystems.

The most common bird species of fell ecosystems include the willow grouse and the rock ptarmigan. Rock ptarmigans inhabit areas well over the tree line, whereas willow grouse thrive in lower elevations. Many bird species common to tundra regions also like to use fell summits as their nesting areas. The snow bunting, the Eurasian dotterel and the long-tailed skua are examples of such species. 

Like its name suggests, the rock ptarmigan blends in well on rocky fell slopes.