The population of Pyrenean bears is increasing but the question of inbreeding is not settled

It’s a mixed feeling for the pro-bears. First, the satisfaction of seeing a litter record for the second year in a row, with elements that tend to show that 2022 will also be a year for babies. But scientific data on the genetic heritage of the Pyrenean group show that the average inbreeding coefficient has doubled in 15 years. Without the contribution of external females, the group would be in danger of dying out by the next century.

Fifteen cubs born in 2021

The OFB is based on what it calls a minimum number detected, taking into account the possibility that certain individuals pass under the radar despite the various tracking techniques: traces, hairs, droppings and evidence of predation. Counting the births of the year and the dead animals (two bear cubs, and Caramelles the female killed in Ariège by a hunter in November 2021), this number covers the entire Pyrenean, French and Spanish chain in 2021, at 70 bears. Thus, considering that the sex is not determined for four of them, 34 females and 32 males populate the Pyrenees mainly in Ariège and Haute-Garonne. In 2020, this number was initially increased to 64 individuals, before being reduced to 68 after new identifications.

With the eight litters arriving in 2021, 15 babies were born, one less than in 2020. Of the 16 cubs born in 2020, the OFB estimates that nine survived. This is a fairly high survival rate which, however, tends to drop over the years, possibly due to the number of breeding males known to sometimes kill the young to force the mother to breed with them. Since 2016, a majority of males are born in Pyrenean litters. “It does not pose a problem for the health of the population, it is statistical, it had to be balanced. Even if, ideally, we would prefer to have more females for the future of the population”, assures Alain Reynes the director of the Pays de l’Ours-Adet association.

Range of bears in the Pyrenees in 2021, massively in the Ariège Couserans.
OFB

Pro-bear associations are especially pleased to see that many cubs born in 2021 come from adults who are reproducing for the first time. This is the case of the Slovenian bear Goiat, released in 2016 in Catalonia, and whose union with Caramellita gave birth to a small female in Ariège. Ditto in Béarn for Sorita, another Slovenian plantigrade introduced. After losing her first litter in 2019, she just had three little males. “Added to this are the young that Néré had with several females, one of the rare adults not to have the same ancestor as the others. Genetic variability progresses even if it is not perfect“, rejoices Gérard Cosimon, president of the FIEP, the Eco-Pastoral Intervention Fund, an association for the protection of nature based in Pau.

An inbreeding difficult to curb

This is the challenge for the next few years, to diversify the group’s genetic profile. For this, scientists rely on the few rare bears that do not have Pyros in their family tree. And they are not many. Pyros, a Slovenian bear released in Melles (Haute-Garonne) in 1997, is the father, grandfather or great-grandfather of nearly 90% of individuals. He even mated with his own descendants. The worst example of this inbreeding: the male Moonboots born in 2006 has Pyros as his father who mated with his daughter Caramellita from his union with his other daughter Caramelles.

Of all the genes in the bear population, 50% come from Pyros. And with the female Hvala which is the other genetic pillar of the group, we arrive at 70% of the heritage ensured by two individuals. —Alain Reynes

As a result, not only only a handful of animals like the male Néré or the Spanish female Bambou have no genetic link with Pyros, but the Pyrenean strain has almost disappeared. Its only representative Canellito, the son of Cannelle, has not yet had any descendants. For Alain Reynes from Pays d’Ours-Adet, the observation is less optimistic than his colleague from the FIEP. According to him, the average inbreeding coefficient in Pyrenean bears has fallen from 0.063 in 2006 to 0.132 in 2020.”Scientifically it is estimated that a genetically healthy population has an effective size of 50 individuals. In the Pyrenees, this size is 8.2. We are still far from it, the lights are orange or even red“, laments the pro-bear activist.

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Without new releases, extinction in the 22nd century?

Does inbreeding already cause problems? No answer the specialists, there is for the moment no apparent signs of genetic degradation Population. But she could, eventually. Two major risks: the decline in fertility and the group’s vulnerability to epidemics. Everyone also agrees that, without the arrival of new individuals, the population could die out within a century.

An ultra-political subject, it brings up the question of new bear releases in the Pyrenees. In January 2020, Emmanuel Macron announced the end of the reintroduction. In January 2021, the European Commission asks France to replace bears that have died because of humans. For two years, four bears have been killed: two on the Spanish side (Cachou in April 2020 and Sarousse in November 2020), two on the French side (Gribouille in June 2020 and Caramelles in November 2021). “Without a new female, the species is threatened. In Béarn there are not enough individuals. And overall you need more animals with more genetic variation“, plus Gérard Cosimon.”We expect a lot from Claverina, Sorita’s comrade, the last two Slovenian bears introduced. Claverina hasn’t had a cub yet“, concludes the president of the FIEP.

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A study by the Natural History Museum in 2013 recommends reintroducing 17 bears eventually in the Pyrenees, ideally 13 in the western core (Béarn) and 4 in the central core (Ariège/Haute-Garonne). Since 1997, eleven bears including 8 females have been released in the French Pyrenees, the last in 2018. Only three of these eleven Slovenian plantigrades are still alive.

A drop in attacks

The French Office for Biodiversity, an independent public body, also gives its latest figures on predation. In 2021, in the French Pyrenees, the number of bear attacks on domestic livestock decreased to 331 attacks compared to 369 in 2020 and 349 in 219, causing the death of 570 animals. 83% of attacks took place in Ariège12% in the territory of Haute-Garonne.

The OFB assumes that these figures are probably underestimated compared to the actual predation. Damages compensated for the benefit of the doubt are not counted.


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