The eagle owl is a bird of prey that had a population of 42 pairs in Osona in the 1990s. However, according to ecologists, the use of rodenticides on farms was one of the factors that led to a large drop in the population of these specimens, reaching zero in 2014. For this reason, the Grup de Naturalistes d'Osona has been working on their recovery for some time and this year has already detected six pairs that live between La Plana and the Sau area.
This species of owl is a natural predator of rodents and for this reason it has become a hope in the fight against the rabbit plague that affects Catalonia. Precisely, this type of predators have a fundamental role in the recovery of this balance of the ecosystem. Jordi Faus, a member of the Grup de Naturalistes d'Osona, points out that the Eagle Owl, as a natural predator of rabbits and rats, is a great ally in the natural control of these populations.
Carles Martorell, also in the Grup de Naturalistes, explains that during the breeding season, a pair of these owls with two or three young can eat up to 240 rabbits, which translates into around 1,500 rabbits throughout the year. "Imagine the great control that could be done of the rabbit plague if we had the population of dukes that there was in the 90s," laments Martorell.
To try to promote the recovery of the eagle owl in Osona, almost twenty specimens from the Generalitat Torreferrussa wildlife center have been released. However, of these, many have died. The six stable couples that exist right now are those that have survived from Torreferrussa, but also others that have settled naturally.
Faus explains that they are young specimens from neighboring regions, such as Vallès or Bages, "who come here, see that there is food and try to settle in." The availability of the rabbit in the territory is so evident that in some nests they have come to find remains of up to eight specimens, says Carles Martorell.
One of the factors that is pointed out as the cause of the death of owls is the intense use of rodenticides by farms to kill rats and mice. In this sense, from the Grup de Naturalistes a lot of pedagogy is done so that farmers start using equally effective methods, but much less aggressive. They know that many times the farms do not use it because of price, but because of ignorance.
Ecologists argue that only if the use of current rodenticides, which have a high concentration of anticoagulants, ends, will a real recovery of species such as the eagle owl be noticed. In fact, the European directives already go in this direction and in the not too distant future it will be forced to change rodenticide products with anticoagulants for other alternatives that do not affect carnivorous species that feed on rats or mice.
Along these lines, the group has studied how pairs that feed exclusively on rabbits survive, while these specimens that also go to farms sooner or later fail to reproduce. "There is a clear differentiation by diet," highlights Martorell.
"It's the same joy as if it were to rain one day," says farmer Marc Crosas wryly. The rabbit infestation coupled with persistent drought is a headache for many farmers who only see obstacles in their work. “I hope, for everyone's sake, that the rabbit plague doesn't continue. They are precious animals, but when they eat our food we have to do something”, claims Crosas. "Now we see the eagle owl as a grain of sand that can help," says the farmer.
