The two main habitats present on this route are:
The highest peaks in this region rise over 2,000 m, Peña Ubiña being the highest, soaring up 2,414 m above sea level. The high mountains boasts stony and rocky terrain as well as almost sheer slopes at the highest altitudes, providing shelter for exemplary mountain species par excellence such as the rare wallcreeper and the snowfinch. More commonplace, and therefore easier to find, are the rock thrush, the alpine accentor and the alpine chough. This is the breeding habitat of the extremely swift peregrine and the golden eagle, as well as being where the Griffon vulture and the Egyptian vulture regularly make an appearance. Extensive alpine meadows spread out just below these peaks and are exploited to graze semi-free range cattle and horses. Water pipits, blue-headed wagtails and bluethroats can be sighted here, where the meadows are uninterrupted by shrub or holly. Descending from the high mountains, you come to a semi-open area with small trees, mainly birch and beech, and shrub such as hawthorn, rowan, wild rose and briar which are a haven for numerous species of interest, especially the red-backed shrike, the wryneck, rock and ortolan buntings, the whitethroat, the dunnock, the bullfinch, and the elusive grey partridge.
The lower slopes are generally covered with a thick blanket of deciduous forest in which beech, white oak, ash and maple predominate, where forest raptors such as the goshawk, sparrowhawk, European bee-eater and booted eagle abound, coexisting alongside typical passerines of the Cantabrian Mountains such as the marsh tit and common treecreeper. The oldest forests provide shelter to populations of rare species such as the black and middle-spotted woodpeckers.