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Peque, a small black howler monkey, scratches her head as she sits on a thick wooden branch in a wired enclosure with seven other orphaned baby howler monkeys at a rescue centre in Nosara, on Costa Rica’s Pacific coast.
Last year, Peque was one of more than 100 animals to arrive at International Animal Rescue Costa Rica (IARCR) as a result of electrocution on power lines, which primates such as monkeys frequently mistake for trees and vines.
“She was found electrocuted with her mom, who was dead when we found her,” says Francisco Sánchez, a veterinarian at IARCR. “Her tail and hands were burned.”
The centre reported 108 electrocuted animals in 2025, with howler monkeys accounting for up to 90% of incidents. Sánchez says there has been a rise in cases since he joined almost a decade ago and puts it down to increased development in the area, which has become a popular tourist destination and a haven for US and European immigrants.
“Now, we have new areas [of electrocutions] appearing that we didn’t have in the past,” he says. “This is because of the development of houses, restaurants and hotels. We are rescuing from further inside the forest.”
There are hopes, however, that numbers could fall significantly in the future. In January, the country’s constitutional court ruled that the state-owned electricity company, Costa Rican Electricity Institute (ICE), and the Ministry of Environment and Energy (MINAE) had failed to put in place effective measures to reduce and prevent the electrocution of wildlife, mainly involving howler monkeys, on uninsulated power lines in Nosara district.
The court gave them six months to implement “the necessary measures to correct the problem present in the power lines that ICE has constructed in the district of Nosara using bare wiring”.
The ruling comes after 20 conservation organisations and rescue centres, including IARCR, launched a campaign, This Is NOT Pura Vida (a play on a Costa Rican expression of wellbeing and positivity), calling for urgent government action. IARCR went on to launch the court action.
The ruling could have major ramifications for wildlife protection nationwide, says Gavin Bruce, chief executive of International Animal Rescue.
“Although this case was built on data from the Nosara area, the problem is nationwide,” he says. “We will now monitor the implementation of the ruling and consider how best to scale these protections across the entire country. We hope it will force Costa Rica’s electricity providers to finally do what needs to be done to keep wildlife safe.”
In Costa Rica, the only country thought to regularly log wildlife electrocution numbers, electric shock is one of the biggest causes of death among wildlife, with 6,262 cases between June 2022 and June 2023.
MINAE says it has already implemented “a broad range of measures aimed at preventing wildlife electrocution incidents” and that it has “promoted a sustained collaborative process aimed at developing technical and institutional solutions … with the objective of advancing the prevention of wildlife electrocution and the protection of biodiversity”.
A global problem
Although there is plenty of research on the often lethal effect of power lines on birds, there is a lack of global studies on the impact on mammals, making it difficult to quantify, says Justo Martín Martín, an environmental consultant who specialises in the issue, including for the International Union for Conservation of Nature (IUCN).
“There are few systematic studies but there is abundant evidence, from scientific articles to social media reports, that the problem is global,” says Martín. “There are records of primates killed on power lines in all regions where they occur, especially in the tropical forests of America, Africa and Asia, ecosystems where this group is most abundant and diverse.
“Logically, incidents are more frequent where high primate density coincides with a high density of power lines, particularly when forest ecosystems are fragmented,” he says.
The few pieces of research that do exist show the problem is global. For example, in South Africa, between 1997 and 2019, about 432 mammals were reportedly killed on power-line towers and poles, according to an IUCN report. Species included small genets, mongooses, monkeys and lions. A study of Diani, a tourist coastal town in southern Kenya, found 370 primate electrocution incidents between 1998 and 2016.
When it comes to primates, fragmented habitation is the biggest threat. “Primate habitats – mainly forests – are becoming fragmented into isolated patches,” says Martín. “Monkeys perceive power lines as pathways connecting these patches.
“To them,” he says, “a power line is essentially a line of connected trees. As a result, they are electrocuted when attempting to cross roads or move through deforested areas using electrical cables.”
While the initial electrocution kills many animals or can cause serious injuries such as heart issues and kidney failure, there are secondary factors that can affect them after the initial shock.
“They could be dealing with trauma from falling metres from pole to ground or may catch fire because of the heat around the transformers, which can lead to burns,” says Sánchez. “And when they fall on the ground, they could be hit by a car or attacked by a dog.”
The only effective way to eliminate the risk, apart from putting power lines underground, is to use insulated cables, says Martín.
“Additional devices can be placed at the top of poles to prevent animals from reaching the conductors even if they climb up,” says Martín. “These measures can be complemented by installing artificial canopy bridges made of ropes, plastics, or other materials, facilitating safe movement between forest patches.”
Standing in the treatment room at the rescue centre, Sánchez says he is “really happy that at least we have now a ruling that says that, OK, it needs to be addressed. But it needs to be implemented across the rest of the country because it’s not only here where the problem is.” A plan of action for the next three years is expected from MINAI and ICE by the end of June, he adds.
“I’m being realistic because I understand it’s really huge work,” he says. “Even in a small place like Nosara, there’s a lot of work that needs to be done and a lot of stakeholders that need to get together.”
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