Are the bears of the Pyrenees stopping hibernating due to climate change?

Snow has covered practically the entire Pyrenees this week but, on average, this winter is being one of the least cold and with the least snowfall in recent decades in this mountain range. The wild inhabitants of the mountains are accustomed to seasonal variability, but climate change can cause alterations that are difficult to assimilate. One of the possible effects of increasing temperatures in areas such as the Pyrenees is the modification of the hibernation phenomenon in species such as the bear (Ursus arctos).

The images captured last Sunday, March 3, on a local road in the Torán valley, Val d’Aran, in which a bear was seen attacking and devouring a wild boar, in addition to having gained thousands of viewers on social networks and media, have raised the question of whether it is normal for a bear to be so active at this time of year, when one might think that it would normally be hibernating.

In various areas of the French Pyrenees some bears have been seen this winter more than usual at this time and newspapers such as Le Point (February 17) and Le Monde (March 8) have published articles by their correspondents emphatically titling that ” For the bears of the Pyrenees, this is not a winter like others” and that this winter “the bears of the Pyrenees have not hibernated due to the mild temperatures.”

Mild winters, like the current one, so far, motivate changes in the hibernation of some bears, there is no doubt. This phenomenon has been specifically documented in various specimens and years, as demonstrated, for example, in a study by the PirosLife project in 2016.

But, “to say that the bears of the Pyrenees have stopped hibernating due to the mild temperatures is a generalization without a scientific basis,” says Marc Alonso, a Depana technician and expert in the study of bears in the Pyrenees with more than three decades of experience. . In France, they have presented images of the female Sorita, with her young, feeding normally in the middle of winter in the Ossau Valley as an example of the effect of climate change on hibernation, “but a specific case is not enough to make generalizations,” he recalls. Marc Alonso.

Santi Palazón, biologist and technician from the Fauna and Flora service of the Generalitat, specialized in monitoring the bear population in the Pyrenees, agrees in stating that there are not enough studies to draw conclusions about the effects of climate change on the hibernation of bears. the bears in the Pyrenees. “This year we have observed a specific case of a bear on the move at the end of January but we cannot forget that it is relatively normal for some males to be active in February.” “This year there has been little snow and the bears have been able to find vegetation to feed on, so it can be considered normal that some of them have left their caves, making their hibernation shorter,” explains Palazón.

The head of the Natural Environment department of the Conselh Generau d’Aran, Ivan Afonso, details that this winter, despite the mild temperatures during part of the winter, “no significant changes have been detected in the behavior of the bears in the Val d’Aran”. “Bears are not very active in winter and if they do not hibernate it is not so much because of the temperature or lack of snow but because they can find food more easily.” “We have not detected more bears this winter, for example, in the photo-trapping cameras,” says Ivan Afonso.

Marc Alonso details that it is totally normal for, for example, females with one-year-old offspring to leave hibernation if they can find food outside the cave. “These females find it more profitable to go out and feed their young outside than to stay in the cave nursing them.” On the other hand, Ivan Afonso indicates, in the case of the females that have given birth this winter, they are forced to stay in the cave because the babies are too small to go out, even if it is not snowing and it is not cold.

Roberto Hartasánchez, founding partner and honorary director of the Fund for the Protection of Wild Animals (Fapas, an entity based in Asturias that has led several projects to study and protect bears in the Pyrenees), indicates that in the case of the Cantabrian mountain range , “we are not at all clear that climate change has any influence on bear hibernation.” Contradicting the headline published in Le Monde, Roberto Hartasánchez explained to La Vanguardia: “I honestly have to say that this story of bears modifying their behavior due to climate change is something that is not at all proven from a scientific point of view.”