CANTABRIAN CAPERCAILLIE

The Capercaillie in Somiedo

The Cantabrian capercaillie (Tetrao urogallus cantabricus) is the most endangered forest bird subspecies of the Cantabrian Mountains and one of the most fragile wildlife jewels in Somiedo Natural Park. This large grouse — the biggest in Europe — has inhabited the park's mature beech forests and mixed woodlands for thousands of years, but its population has suffered a catastrophic decline in recent decades, bringing it to the brink of extinction. Spotting a capercaillie in Somiedo is an extraordinarily rare and privileged experience.

Characteristics of the Cantabrian Capercaillie

The capercaillie displays marked sexual dimorphism in both size and plumage. The male is an imposing bird with black plumage and blue-green iridescence on the breast, mottled brown wings, a black tail with some white spots that it fans out during the rut, an ivory-coloured bill and a characteristic red fleshy wattle above each eye. The female is considerably smaller and more discreet, with mottled brown, black and white plumage that provides perfect camouflage among the leaf litter of the forest floor. Both sexes have feathered legs — an adaptation to cold — and protected nostrils to withstand extreme temperatures.

• Length of male: up to 1 metre; female around 58 cm
• Weight of male: 3.5–5 kg; female 1.5–2.5 kg
• Longevity: up to 20 years in the wild

Habitat in Somiedo

The Cantabrian capercaillie depends on mature beech forests (Fagus sylvatica), although it also uses oak, birch and mixed woodlands. It requires old-growth forests with multiple vegetation layers, abundant bilberry understorey — its main summer food — and large trees with good structure for roosting. In Somiedo Natural Park, the shaded beech forests of the Pigüeña and Somiedo river valleys, above 900 metres altitude, provide the most suitable habitat for the species. Lekking sites — the forest clearings where males gather to sing — are typically located in open, grassy areas inside or at the edge of these mature beech forests.

The Rut: Lekking Sites

The capercaillie's most distinctive spectacle takes place in April, coinciding with bud burst in the beech forest. Males arrive at dawn at the lekking sites — traditional areas they return to year after year — to display before females. The male fans his tail to 180°, ruffles his neck feathers and performs his characteristic song — a sequence of clicks, knocks and a long final whistle — which gives the genus its name (Tetrao derives from the Greek tetrix, meaning grouse). During the final phase of the song, the capercaillie becomes momentarily deaf, unable to perceive sounds from its surroundings — hence its name in other languages such as German Auerhuhn ("deaf grouse"). Once mated, the female nests alone and takes sole responsibility for incubation and chick care.

Reproduction

The female builds her nest by excavating a hollow in the ground at the base of a large tree or among dense shrubby vegetation, where she lays between 5 and 8 eggs, cream-coloured and finely spotted with brown. Incubation lasts 26 to 29 days and the male plays no part whatsoever in raising the chicks. Hatchlings are nidifugous — they leave the nest within hours of hatching — and hide among vegetation, where they are easy prey for foxes, martens and raptors. Normally only one chick survives per clutch, making its first flights at 15–20 days of age. The survival of chicks during the first weeks of life is the principal bottleneck for the species' recovery.

Diet

The capercaillie's diet varies markedly with the seasons. In spring and autumn it feeds mainly on tender beech shoots, holly leaves, rose hips and rowan berries. In summer, bilberry (Vaccinium myrtillus) forms the basis of its diet, and the presence of this shrub in the understorey is a key factor determining the species' distribution. In winter it relies on holly leaves, heather and conifers. Chicks are insectivorous during their first weeks of life, when they need protein to grow, and gradually incorporate plant matter into their diet.

Conservation Status: A Critical Emergency

The Cantabrian capercaillie is in a critical survival crisis. At the beginning of the 20th century there were more than 10,000 individuals in the Cantabrian Mountains; today between 200 and 300 individuals are estimated to remain, making it the most endangered forest bird subspecies in Spain. It is listed as "Endangered" in the Spanish National Catalogue of Threatened Species. The main causes of decline are fragmentation and degradation of forest habitat, predation — especially by wild boar, which destroys nests — climate change (drier summers reduce bilberry production), disturbance at lekking sites during the breeding season and predation of chicks. Somiedo harbours one of the last viable strongholds of the species and its conservation is an absolute priority.

Signs of Capercaillie Presence

• Lekking sites: grassy clearings inside mature beech forests, with dead trunks and standing dead trees. They can be identified by the accumulation of feathers and droppings around favoured perches.
• Tracks: three robust forward-pointing toes and one very short hind toe. The female's footprint measures 9–10 cm and the male's 11–12 cm in length, visible in mud and snow.
• Nests: a hollow excavated by the female in the ground at the base of a large tree, often among dense shrubby vegetation or sheltered by a fallen trunk. Visiting known nesting areas is strongly discouraged due to the risk of nest abandonment.

Responsible Birdwatching in Somiedo

Given the critical conservation status of the species, any encounter with a capercaillie in Somiedo must be approached with maximum responsibility. Approaching lekking sites during the breeding season (March–June) is strictly prohibited, as even minor disturbance can cause the birds to abandon a lekking ground for several years. Any sighting or sign of presence should be reported to the park's environmental wardens. Observing a Cantabrian capercaillie in the wild is today one of the rarest and most privileged wildlife encounters in Spain.