On September 25, three female Cantabrian capercaillie were transferred from the breeding center and genetic reserve of Sobrescobio (Principality of Asturias) to a large pre-release park in the Picos de Europa Regional Park, where they remain before being released. In line with other reinforcement experiences carried out in Europe, it has been considered appropriate to carry out a release with acclimatization, which consists of accustoming the birds to the future release site thanks to their permanence in a pre-release park that has the same characteristics as the natural environment in which they will be released and will carry out their normal activity.

Initially, the release of four female capercaillie was planned but, unfortunately, on the day of the transfer, the death of one of the specimens was detected due to natural causes. The death could be related to the presence of winged predators that often fly over the breeding center. The first indications of the necropsy seem to point to a heart disease, pending results from the samples sent to the laboratory that confirm this diagnosis. Despite this setback, the release of 3 female Cantabrian capercaillie is already a historic event in our country and entails a very high complexity and risk.

Personnel from the Principality of Asturias, in order to minimize the stress and problems derived from the capture of birds in the breeding-flying parks of the center of Sobrescobio, have used traps installed in it to which the 3 female capercaillie were already accustomed. The specimens were ringed and equipped with a collared radio transmitter, which will allow a control to be carried out once released and to evaluate their adaptation to the new environment.

Once captured, the 3 birds were transported in individual boxes specific for this purpose. The journey to the release park was made in the shortest possible time in a ventilated vehicle, avoiding at all times strange noises that could alter the specimens. Once there, the staff in charge introduced the cages into the pre-release park, where the veterinarians and environmental agents, hidden in a hide and behind a plant screen, were able to verify that 20 minutes after depositing and opening the boxes, the birds left calmly on their own feet.

The pre-release park is large enough (500 m2) for capercaillie to exercise, sleep on high perches or tree branches, fly and take advantage of the natural food that is available inside. The opening of the release doors and the control and surveillance tasks will be carried out avoiding human contact. The park is associated with an outer security perimeter, with barriers installed to prevent access by other animals. The surveillance is carried out by nursery staff of the Junta de Castilla y León, specifically in charge throughout the period of stay of the capercaillie in the pre-release park and their subsequent monitoring once released. In all the work, we have had the support and collaboration of the local population, owner of the mountain where the actions have been carried out.

When selecting the optimal place to install the pre-release farm, the guidelines established in the technical document on population reinforcement, prepared within the framework of the LIFE+ Cantabrian Capercaillie, have been followed, following the following criteria: habitat quality, possibilities of dispersal, presence of the species in the area and levels of protection of the territory. Specifically, the release area presents a habitat of excellent conditions, the forest and supraforest areas have a good coverage of blueberry trees that will provide abundant food and adequate protection for the young caperca-hens, which can hide from predators and defend themselves from inclement weather throughout the life cycle. There are also good chances of dispersal in case the birds do not adapt properly to the release area. In the first days of staying in the park, the capercaults have adapted perfectly to the release area. They sleep on the night perches, mainly raised beech branches, and are quite gregarious among them. Warning clucks are often heard to try to locate each other. During the day they alternate periods of rest with periods of displacement that they use to feed.
The ingestion of leaves and stems of blueberries, beech, heather, salguero and rowan, elderberry and rowan fruits, water from the drops of morning dew or from the artificial pond created within the park and, sometimes, pebbles from the sandboxes placed for bathing have been observed.