Hidden in the thick of the forests, fauna is always present in San Carlos de Bariloche, offering the substantiation of footprints and tracks to the attentive tourist.

One of the emblematic birds of Argentine Patagonia is the stately condor. Their majesty can be seen when they soar above the high mountain tops and glide in circles. From the ground, they are easily recognized by their completely black color, except for a white "collar".

Huemul (deer), pumas, pudu, foxes and woodpeckers can be also found. These are unobtrusive inhabitants of the area.

To the east, lack of rainfall makes for a landscape of ravines and practically dry plateaus, with a total predominance of the Patagonian steppe type weather. This is the kingdom of yellow and orange grasses, typical of the westernmost humid part of the steppe. There, foxes, pumas and guanacos wander, together with birds of prey, such as the cinereous harrier and the American kestrel, typical birds of the area.

On the cliffs of some of the Nahuel Huapi islands, there is a population of blue-eyed cormorants, a really curious fact, as this is for the most part a seagoing species. It is also common to see kelp gulls following the boats.

One of the typical fauna species of the region is the huilln, a predator mammal that has its main population in this park of Argentina. This is a native otter that lives on the borders of lakes, lagoons, rivers and brooks. It has a long body covered in brown fur, highlighted with reddish or orange hues, short legs and a long tail.

Another interesting species is the colonial tuco-tuco. This is a rodent that lives in underground warrens and its natural habitats are limited to Nahuel Huapi National Park.