- The population estimate carried out using genetic individualisation techniques for non-invasive samples has represented an increase of 8% compared to the data obtained in 2019
- 56% of the specimens registered were males and 44% females, distributed in the provinces of León, with two thirds of the population, and the Principality of Asturias with one third of the individuals
- The detailed monitoring of the conservation status of the capercaillie population is one of the priority lines in execution within the recovery program underway since 2018
The Working Group created after the declaration “in critical situation” of the Cantabrian population of capercaillie Tetrao urogallus has completed the work to estimate the total number of individuals present in the Cantabrian Mountains in 2024. The result is 209 different capercaillie, which represents an increase of 8% compared to the 191 estimated during the previous full sampling in 2019. Of those 209, 117 (56%) are males and 92 (44%) females. In the previous census, the deviation of the sex ratio towards males was more pronounced (31.5% females: 68.5% males) while in this population estimate for 2024 the detection of females has been higher.
Based on the number of genetically individualized specimens, 67% of the population inhabits the León regions of Alto Sil, Laciana and Omaña mainly, with scattered specimens present in Ancares and El Bierzo. 33% is distributed throughout the Principality of Asturias in the councils of Degaña, Cangas de Narcea and Ibias.
The population estimate of the Cantabrian capercaillie has been promoted by the Working Group, which reports to the Flora and Fauna Committee. This Working Group is made up of representatives of the autonomous communities with a current or recent presence of capercaillie (Castilla y León, Principality of Asturias and Cantabria) and is coordinated by the Directorate General of Biodiversity, Forests and Desertification of the Ministry for Ecological Transition and the Demographic Challenge (MITECO).
It has the support of external advisors specialized in the conservation of the species, the scientific field, conservation societies and expert consultants.
To carry out the work, we have had the advice and collaboration of two public scientific institutions of reference worldwide. CIBIO – Centro de Investigação em Biodiversidade e Recursos Genéticos, based in Porto, Portugal – has developed techniques for the genetic identification of non-invasive samples (droppings) leading to the identification of capercaillie. For its part, the Institute for Research in Game Resources of the CSIC has designed the sampling methodology, trained the field technicians and carried out the statistical analyses for the estimation of the population size of the Cantabrian capercaillie based on the information of identified genotypes.
The fieldwork was carried out between the months of April and June 2024 by personnel from the autonomous communities and MITECO. 320 units (plots, 177 in Asturias and 143 in León) were sampled with an approximate area of 17.5 ha each. The total length of the transects traveled in critical areas for the location of capercaillie droppings was 1,185 km. A total of 959 samples were collected and subsequently stored and identified for genetic analysis, 719 in Castilla y León and 240 in Asturias. Of the total samples analyzed, 393 were genotyped and assigned to 106 different capercaillie. The estimate, based on capture-recapture models, resulted in 209 capercaillies, with a 95% confidence interval of 171-251 birds, of which 117 (56%) are males and 92 (44%) females.
A GREAT LONG-TERM
EFFORTThe results of the 2024 population estimate show that there is still a long and complex way to go to move the capercaillie away from the risk of extinction. There are barely two hundred individuals that survive in the Cantabrian mountains. This is the second complete population estimate to be carried out for the Cantabrian population after its declaration “in critical condition” in 2018, so it is premature to draw conclusions on the population trend based on two population estimate data with the same methodology, as well as on the impact of the conservation measures implemented to date. However, the 2024 results are the first in the entire historical series of population data to show a halt in the decline of the species. It can even be concluded that there is a slight increase in the population based on the statistical analyses carried out that indicate, with a 75% probability, that the population of 2024 is greater than that of 2019.
The higher relative proportion of females obtained in this census is also positive. Female capercaillie are the key population group to be favoured through the in situ conservation measures underway, due to the ecological and demographic role they play, in a polygynous species such as the capercaillie. Females assume most of the investment in reproduction and rearing of chicks and suffer higher rates of natural mortality, so their protection and promotion is essential to increase the values of reproductive success.
The results of 2024 encourage the continuation of the important conservation efforts that have been underway since 2018. A new estimate is expected to be undertaken in a shorter period of time, probably in 2027, in order to have updated information more frequently. The ongoing population monitoring tasks carried out annually, such as the parameters of censuses and productivity, coincide with the trend of population estimation, and also include knowledge of other demographic aspects essential for the adoption of adaptive management measures. Reproductive success is being evaluated annually through summer census drives – which for the period 2018-2024 has resulted in an average of 1.14 chicks/female for a total sample of 129 controlled capercaillie females. There is also a growing knowledge of the mortality factors of capercaillie, showing that of the 17 specimens found dead since 2018, 13 were killed by predation, one died by collision and for three the causes are unknown. The evaluation of individual capercaillie survival rates, the use of space, the selection of trophic resources and the recognition of the behavioural patterns of females between different periods of the year are also being known, thanks to the radio-tagging with radiofrequency emitters of more than 50 capercaillies in the last 10 years in the Cantabrian Mountains.
Among the lines of conservation underway, it has been possible to increase the values of reproductive success in recent years thanks to the reduction of predation pressure by generalist and common mesomammals in the area, especially the marten (Tuesday). Comparative evaluations have shown an average increase of 0.5 chicks/female in summer samplings of reproductive success, between areas with and without reduction in predation pressure. This would mean, for example, an additional addition to the population of about 50 chickens annually in the event that 100 capercaillie were to reproduce. This urgent measure is considered a “last resort” and, in any case, of short-medium term duration until the critical situation of the Cantabrian population can be improved.
Habitat improvement work in areas with the current presence and potential expansion of capercaillie is also being carried out within the framework of the Cantabrian capercaillie conservation programme. Their objective is to replicate, through forest management tasks, the structures, composition and provision of resources of the forests that most favor the capercaillie, based on scientific knowledge of the ecological requirements of the species. That is why actions are being carried out in key forest masses for the expansion of areas favourable to the capercaillie in terms of scrub structure and tree cover, which favour two fundamental aspects: increasing the availability of trophic resources and improving the protection, resting and mobility capacity of the capercaillie. All this work is being scientifically evaluated to verify its effects on the ecosystem and on the capercaillie itself.
Captive breeding of the capercaillie is another of the lines of action with which it is intended to improve the conservation status of wild populations by reinforcing nuclei of current presence of capercaillie and reintroduction in areas where the species inhabited until a few decades ago and that currently have positive characteristics to welcome it again. Although no individuals have yet been released into the wild after the capercaillie was declared critical, the two captive breeding centres of the ex situ conservation programme (Valsemana and Sobrescobio, managed by the Junta de Castilla y León and the Government of the Principality of Asturias, respectively), are finalising the most effective breeding techniques and forming the breeding stock. The objective is to have 40 females and 20 breeding males in the facilities of the breeding center of Valsemana (Castilla y León) and to release at least 80-100 specimens annually once the centers are fully operational. In 2024 there are already 38 Iberian capercaillies, of Cantabrian and Pyrenean origin, with which breeding tasks are carried out. It is expected that the first releases can be carried out in 2026, following the programming and numerical objectives set within the Working Group.
AN ESSENTIAL COLLABORATION, WITH THE SUPPORT OF THE SCIENTIFIC SECTOR
The Cantabrian capercaillie is one of the nine species in a “critical situation” in Spain and, for this reason, the environmental authorities of our country, with the coordination of the General Directorate of Biodiversity, Forests and Desertification of MITECO, are developing important economic and logistical investment efforts to prevent its extinction. The declaration “in critical situation” is a pioneering administrative figure at the international level, which aims to comply with legal commitments to prevent the loss of global biodiversity. In the case of the capercaillie, the actions underway are part of the technical scope of the Development Strategy for the conservation of the capercaillie in Spain, which are implemented at the regional level through the official recovery plans underway, such as that of Castilla y León.
In order to optimise the effectiveness of capercaillie conservation actions, it is very important to have the collaboration of civil society as a whole, starting with the important role played by sectoral organisations interested in the conservation of the species, specialised experts and consultants and, above all, scientific institutions that support and advise public administrations in carrying out management tasks. For the capercaillie, the contribution of research centres such as the CSIC, through its centres Institute for Research in Game Resources (IREC), the Institute of Evolutionary Biology (IBE), the Pyrenean Institute of Ecology (IPE) or the National Institute for Agricultural Research (INIA), the Universities of Cordoba and the Polytechnic University of Madrid, or the Forest Technology Centre of Catalonia, It is being essential to be able to know and inform in the most appropriate way the work in progress.
Likewise, the international collaborations of the capercaillie conservation program are enriching and improving the scope of actions, especially in the field of captive breeding. This is the case of the collaborations with the French Republic, with whose government there is a technical cooperation protocol for the development of the ex situ conservation programme – mainly through the transfer of Pyrenean capercaillie clutches – and the public administrations of Poland for the exchange of best practices in captive breeding.
