How many Iberian ibex should they live in the Sierra Guadarrama?

Through an experimental design suitable to the characteristics of the area, the vegetation and the studied species, a researcher team from School of Forestry and the School of Agricultural Engineering at UPM has assessed the damage caused by browsing (use of branches and leaves of woody plants) on each plant species and they compared them with their availability. This way, they were able to quantify the food preferences for the Iberian ibexes and to identify the most valuable vegetal species as indicators of the number of animal acceptable to guarantee the ecological sustainability in the mountains of Madrid.

The extinction of large animals by human beings or defaunation is considered a significant threat to global biodiversity in Spain, for example, the bucardo or the Iberian ibex of Pyrenees (Capra pyrenaica pyrenaica) were very recently extinguished, in 2000. Therefore, reintroduction is more frequent now, that means, the introduction of species in zones where they had recently disappeared. The idea is to restore the natural biodiversity, ensure the persistence of endangered species and restore its original range.

Today, an example is the mohor antelope, which became extinct in Mauritania but it is still preserved in Spain and whose reintroduction in that country is scheduled for this year. Another example is the Iberian ibex (Capra pyrenaica victoriae) in the Sierra de Guadarrama that, after its extinction in the late nineteenth century, was reintroduced in 1989. The case of the Iberian ibex was successful and this species has returned to play an important ecological role and is an attraction for the Sierra, which is declared a national park.

However, given the almost total absence of predators, the Iberian ibex population grows in geometric progression, and from the 67 specimens introduced until 1992 they are more than 3,300 now only in the area of La Pedriza, where there are over 47 specimens per km².

Thus, the problem now is to identify how many Iberian ibex should live in the Sierra: they should be a sufficient number in order to carry out their ecological function, but not so many that they can entail health problems or degradation of flora and vegetation. In fact, the vegetation of the Sierra is also protected by the European Habitats Directive, the Law on Natural Heritage and Biodiversity, and the Regional List of Endangered Species of the Community of Madrid. This problem also occurs with other species in many Protected Natural Areas and it is necessary to address the problem with a scientific approach which is solid and extrapolated to other cases.

The study conducted by researchers at Universidad Politécnica de Madrid has addressed the problem by using woody plants as indicators of viability of the population of ungulates. They have found that some protected species such as holly, birch, yew or rowan, already exceed the admissible levels of damage due to browse. The method, which was also used with the deer in the Montes de Toledo and the Barbary sheep in Sierra Espuña (Murcia), can be used for other species of ungulates and other ecosystems, particularly in protected natural areas.

Once an acceptable angulated population is reached (the Iberian ibex in this case), the issue is to maintain that population stable, taking into account that sport hunting is forbidden in National Parks. Thus, as the famous writer Michael Ende said: 'but that is another story and shall be told another time.'

Link of interest: https://vimeo.com/125398829