Wild ungulates have experienced an extraordinary increase in number and expansion in occupancy in Europe (Apollonio et al., 2010) and in the Pyrenees (Gortázar et al., 2000; González et al., 2013) in the last decades. Southern chamois Rupicapra pyrenaica is one of these species. This mountain ungulate is widespread, abundant, and increasing. It is adapted to high elevations and cold climates (Corlatti et al., 2022), occupying altitudes between 1,000 and 2,800 m asl. It is endemic to Southern Europe and has three subspecies: Rupicapra pyrenaica parva, living in the Cantabrian Mountains, Rupicapra pyrenaica ornata, in the Appenines and Rupicapra p. pyrenaica in the Pyrenees (Herrero et al., 2020). In 2002 the population of Pyrenean chamois was estimated at around 53,000 animals, comprising one single metapopulation (Herrero et al., 2004). Even if there are no complete figures of its historical distribution in the whole Pyrenees, in the mid-19th century it was marginal. Since the mid-20th century, the population experienced an extraordinary expansion and today occupies the whole mountain chain (Gortázar et al., 2000).

This endemic Pyrenean subspecies is found in alpine meadows, rocky areas, forested valleys, and lower slopes in mountainous regions. Pyrenean chamois is a mixed grazer or intermediate feeder (García-González & Cuartas, 1996) adapted to high mountain environments with pastures, scrubs, and forests. The subspecies has occupied its potential habitat in the mountain range and has been subjected to sporadic outbreaks which produced important mortality (Arnal et al., 2013; Corlatti et al., 2022). It generally stays above 1,800 m in alpine meadows during the warmer months of the year (Corlatti et al., 2022). Some populations have started to inhabit forests permanently (Herrero et al., 1996), even if their ecology is poorly known. Expansion continues nowadays on the border of the distribution of the subspecies, creating new subpopulations (Antón et al., 2019) and showing sporadic presence in marginal areas (Sampere et al., 2023).

It is considered of Least Concern under IUCN criteria, listed in Appendix III of the Bern Convention and Annex V of the EU Habitat Directive (Herrero et al., 2020) and suitable to be hunted in the whole Pyrenees except for the Navarre region, Spain. Nowadays it is a relevant primary consumer, important huntable trophy and a touristic attraction. Reintroductions have been frequent in the French part of the Pyrenees (Corlatti et al., 2022).

In February 2022 we received the testimony of two local hunters on the presence of Pyrenean chamois living for a long period (since 2007, 15 years) in a forest area of Southcentral Pyrenees (Fig. 1). They were asking the Regional Government for a chamois quota for their hunting ground. As there was no previous information on this issue, we decided to undertake a one-year monitoring system to increase the knowledge of this particular situation. In this short communication, we would like to describe the demographic characteristics of the subpopulation and comment on the possibilities that this new situation creates.

We performed block counts (Berducou et al., 1986, Herrero et al., 2011) of the area where Pyrenean chamois was supposed to dwell once in April (before parturition), June (after parturition), September and November (rut) during 2022. Four operators walked in the area after sunrise following a planned route using binoculars, spotting scopes, mobile phones and cameras, for a period of around 4 h. When Pyrenean chamois individuals were sighted, animals were registered in a sheet. Double counts were avoided gathering together information at the end of each survey, considering sex, age, localization, and timing. Occasional sightings were also recorded.

Table 1 shows the results of the survey (Fig. 2). There were sighted at least 18 chamois during the whole study period. Movements from the neighboring Sierra Ferrera could not be discarded. The subpopulational stock is very low compared to other Pyrenean subpopulation (Herrero et al., 2004), but the population structure is comparable to other forest populations (Garin & Herrero, 1997). Even habitat use and grouping are comparable to other forest dwelling populations of the species (Herrero et al., 1996, 2002). The occupied area is around 2 km2 and the density is 9 chamois km-2, moving in an altitudinal range of 600-650 m asl.

Even if this altitudinal and habitat pattern can be considered as an exception, Pyrenean chamois could inhabit forests with strong slopes below 700 m permanently. This would mean a significant increase in its distribution range surpassing the current consideration of the species as an exclusively high mountain dweller. In any case, steep slopes are a fundamental requirement for the reproduction of chamois since females need vertical areas to give birth and have their young protected from terrestrial predators when they cannot flee (Pérez-Barbería & Nores, 1994).

It has to be considered that global warming (Lovari et al., 2020), encroachment (García-Ruíz et al., 2021) and forest increase (Lasanta & Vicente-Serrano, 2007) are reducing chamois habitat and quality. The occupation of these low elevation areas can represent an alternative to their traditional habitat. This preliminary work is the first document that shows a Pyrenean chamois population living all year long for a long period under 1000 m of altitude. Additional work is needed for corroborating this potential trend and studying the variables involved in this process.