The common capercaillie (Tetrao urogallus) is a galliform bird, nicknamed the “grouse of the woods” because it is a species of mountain and boreal forests. There are some differences between males and females. Male capercaillie, larger and larger than females, weigh between 3 and 4 kilograms and are between 75 and 90 centimeters tall. They have dark plumage with a blue-green collar and a long tail that they fan out during the mating season. Females weigh between 1.2 and 2 kilograms and are between 52 and 68 centimeters tall. Unlike males, females are covered with orange-brown and reddish plumage.
 
In the Iberian Peninsula there are two subspecies of capercaillie, one in the Cantabrian mountain range and the other in the Pyrenees. The Cantabrian capercaillie occupy the upper part of the forests (between 1,000 and 1,700 metres above sea level) and the supraforest border.
 
The mating period of these birds runs from the end of March to the beginning of June. Male capercaillie practice a ritual in areas called “cantaderos” where they strut and sing songs to show off in front of the females. After mating, females deposit between 6 and 8 eggs, which they incubate for 26 days.
 
The capercaillie feeds on the plants it has at its disposal depending on the time of year and the place where it lives, as they eat a different menu in each season. During the winter, holly leaves and green blueberry stems are part of their diet. In spring they feed on food rich in protein and fiber that they find in the shoots of different plants. During the summer, they consume mainly blueberries and other berries (blackberries, raspberries or strawberries) and in the autumn months they eat acorns and fruits of rowan, hawthorn and rose hips. However, chicks are insectivorous until they are four weeks old, basing their diet on ants, grasshoppers or beetles.  
 
The presence of capercaillie can serve as an indicator of the state of conservation of an ecosystem and its biodiversity. The Cantabrian subspecies is considered endangered, as it has been declining in number in recent years. At present it is estimated that there are about 200 -300 specimens that inhabit the Cantabrian mountain range, focusing its population in areas of the Principality of Asturias and Castilla y León, with a few specimens also in Cantabria.
 
Among its main threats are population fragmentation, loss of favorable habitat, isolation of specimens, predation, competition with other herbivores, collision with unmarked power lines and dangerous livestock fences, as well as other causes derived from human activity, such as hunting on the species for decades. currently prohibited. Climate change is also presented as a likely cause of its population decline.  
 
Due to the situation of this species, the The Biodiversity Foundation of the Ministry of Agriculture, Food and the Environment coordinates the Life+ Cantabrian Capercaillie project,  50% co-financed by the European Union, through the LIFE+ funds, and which has as partners the autonomous communities of Cantabria, the Principality of Asturias and Castilla y León, the latter through the Natural Heritage Foundation of Castilla y León; the Inter-regional Consortium for the coordinated management of the Picos de Europa National Park; SEO/BirdLife and Tragsa and Tragsatec and with the co-financing of the Autonomous National Parks Agency and the Iberdrola Spain Foundation.