"Saving two adult birds or four young eagles per year would be enough to stabilize the Bonelli's eagle population.”
Ninety-two Bonelli’s eagles in the Catalonia region of northeastern Spain died from electrocution on power lines between 1990 and 2014, according to a study published in Biological Conservation. With only around 1,000 breeding pairs found on the Iberian Peninsula — which is where the better part of the worldwide Bonelli’s Eagle population resides — electrocution poses a major threat to these endangered birds.
The power line problem extends beyond this one species. American bald eagles in the US, for instance, are also commonly killed by electrocution.
Meanwhile, at their current rate of decline, the Bonelli eagle population inhabiting the Iberian Peninsula is in danger of completely disappearing.
A team of researchers from the University of Barcelona in Spain and Université de Montpellier in France gathered data on the various causes of Bonelli’s eagle mortality. Burns on the claws of deceased birds pointed to electrocution as the cause of death, while shotgun pellets were signs that birds had been hunted.
By modelling their population fluctuations and mortality, the researchers determined that reducing the number of birds electrocuted each year was the key factor that could potentially guarantee the population’s viability — an idea that had previously been met with controversy due to lack of quantitative analysis.
They also suggest that a relatively small effort could yield massive conservation returns for this species. "Saving two adult birds or four young eagles per year would be enough to stabilize the Bonelli's eagle population,” says study co-author Joan Real in a press release
The researchers then set out to design a protocol that would keep the birds safer from electrocution. They identified the most deadly power towers for Bonelli’s eagles, which tended to be those made of conductive materials like metal or reinforced concrete, and recommended these be insulated or substituted for safer ones.
A pilot test of the protocol in Parc Natural de Sant Llorenç del Munt in Barcelona showed promising results, with eagle mortality decreasing from 23 percent to zero after the protocol was implemented.
However, as Real notes, no power lines in Spain have been corrected yet (outside of the pilot study), and thousands of birds continue to die from electrocution each day.
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