The population of brown bear of the Cantabrian mountain range (Asturias, León and Palencia) is one of the most vegetarian in Europe. In spring, it is based on grasses and other herbs; in the summer he chooses fleshy fruits, especially for blueberries, and in the beginning of autumn and in winter the acorns become his main allies. A source of food and shelter that will be altered by climate change. Researchers of the Higher Research Council Scientists (CSIC), of the Mixed Unit of Research in Biodiversity and of the University of Oviedo, have published a study in the prestigious magazine Global Change Biology, which concludes that there will be a significant decrease in the current distribution of seven critical plant species for feeding and shelter of the bears. The study focuses on blueberries, beeches, chestnuts, three kinds of oaks and wild pines. As a result, adds the document, it is expected that the population of bears in the Cantabrian mountain range "will drop drastically in the next 50 years".
If nothing changes, the simulations carried out by the scientists present a bear that will move towards the north of the mountain range and, before the decrease of the food in the mountains, it will look for it in lower lands, which can cause conflicts when reaching more humanized areas than current ones. In addition, the plantigrade could alleviate the lower availability of fruits and acorns with a more carnivorous diet. The study makes these predictions taking into account two scenarios of greenhouse gas emissions: moderate (temperature increase between 1 and 2.6 degrees in 2100) and pessimistic (between 2.6 and 4.8 degrees in 2100), and for two periods of time, 2050 and 2070.
At present, there are two subpopulations of brown bear in the Cantabrian mountain range: the western one, with around 250 specimens (35 breeding females and 64 young in 2017) and the eastern one, with greater problems to get ahead, where the figure drops to about 40 (six breeding females and nine offspring). As a result of these habitat modifications, "The population of brown bears seems to drastically lose its current distribution in the future," says the article. In the moderate scenario, both for 30 years and 50 years, it drops by approximately half. In the pessimistic option the decrease would be "dramatic": in 2050 it would maintain 24% of the current population and in 2070 it would sink to 12%.
Three negative effects on this population can be expected. In the first place, a drastic reduction of oak forests - which give acorns - that can affect the storage of fat before entry into the osse, essential for hibernation and the breeding of cubs. Second, competition for the precious fruit with other animals, such as wild boar, would increase. And finally, the distance that would separate the oaks from the blueberries, as they are not concentrated in one place, may cause greater risks for the plantigrade, which should be displaced at greater distances to obtain both foods with the consequent expenditure of energy.
The beech forests of the Cantabrian mountain range seem to be the most affected, according to the scientists' estimates. In the more moderate scenario, the distribution (latitude and average altitude) of the beech groves is reduced by half and, in the most pessimistic, they almost disappear. The location of the blueberries is similarly lucky, contracting in half, as happens with the oaks, both the pedunculados (Quercus robur) like the sessiles (Quercus petrea) On the other hand, the chestnut trees and pines endure, and their distribution changes "slightly".
"Predictions play a crucial role in alerting scientists and the people involved in making decisions about possible future risks," explains Vicenzo Penteriani, one of the authors of the research. "The fundamental thing is that it shows that strategies must be developed that extend beyond the current moment and be more effective," he adds.
Scientists warn that these projections can not take into account the "adaptive responses" of the bears, which are "potentially complex" and that would allow them to adapt to other foods.In any case, "the magnitude of forest changes projected by our models to conserve the population of the Cantabrian brown bear, it would be necessary to go beyond maintaining the historical and current distribution and dedicate ourselves to the areas where they could expand, "explains Penteriani." We can not force the plant species to remain in a place where they can not survive or the animal species to resist where the main resources have disappeared ".
The Modifications described in terms of species distribution and habitat loss they are a consequence of the expected response of vegetation to climate change. The current wilderness areas of the Cantabrian mountain range are mainly found in mountainous regions, where scientists have foreseen the biggest changes, with mountain species subject to increasing temperatures and changing rainfall. For example, scientists specify, among the known effects of global warming "we know that the drought reduces the growth of blueberries and the size and maturation of the fruit, an effect that is expected to be stronger in the southern limit of its European range, as in the north of Spain ".
To find out where the specimens move, researchers have used data from organizations that have been monitoring the bear for decades: the Brown Bear Foundation (FOP) and the Wildlife Protection Fund (Fapas), in addition to the Principality of Asturias and the Junta de Castilla y León.