The first time Chris Martin heard a howler monkey’s cries, he thought it was a jet plane taking off. Martin was an epidemiology student visiting Costa Rica’s La Selva Biological Station as part of a tropical rainforest ecology program and had set out on a walk through the nearby jungle with his group. He says that at first, he hadn’t noticed the handful of primates wandering the tree branches above him. “Then all of a sudden came this really jarring roar,” says Martin. “It was so loud it was like standing next to a speaker at a concert.”
With calls that can reach up to 128 decibels, howler monkeys are considered some of the loudest animals on Earth. They get their name from the cacophonous cries they emit—booming, guttural roars that can be heard for up to three miles through a dense forest. Costa Rica is home to the mantled howler monkey, which typically lives in groups of 10 to 20 members and is mainly tree-dwelling, traveling throughout the forest canopy in search of food. However, in areas of increased deforestation, such as rural and coastal stretches where clear-cutting is an issue, these primates are often forced onto the ground to search for food, where they can be run over by cars. Even worse, they mistake power lines for natural vines in areas where there’s not ample forest cover, a costly mistake that often ends in electrocution.
According to International Animal Rescue (IAR), a non-profit dedicated to the animal protection and conservation of wildlife worldwide, electrocution is the number one killer of howler monkeys within the country. However, with a new government decree aimed at reducing the harmful effects of power lines on Costa Rica’s wildlife, there may be hope for sparing the treetop primate from this unnecessary and gruesome plight.
How Power Lines are Harmful to Wildlife
Hundreds of howler monkeys—as well as other and other wild animals—are electrocuted on uninsulated power lines and transformers across Costa Rica annually. “It’s a problem that’s happening in rural areas throughout the country, ” says Gaby Campos, program director for IAR Costa Rica. The lines are dangerous, but it’s the high-voltage electrical transformers—the ones used to lower the voltage from high-voltage distribution lines to the reduced amount needed by homes and businesses—that are the real killers.
Unfortunately, the exact number of fatalities remains unknown since a howler monkey’s death isn’t always reported. For instance, when a monkey gets electrocuted, it will often blow a fuse that the electric company will have to come out and fix. But if a monkey is killed and the electricity supply hasn’t been disrupted, nothing is done, and the casualty goes unrecorded.
Then there are the howler monkeys that succumb to complications suffered from electrocution while on the road to recovery. Although most animals are killed on the scene, others bear injuries that range from broken bones and concussions to muscle spasms and heart issues. Then, you have primates carrying their babies at the time the shock hits. While the mother takes the brunt of the current, electricity still runs through their offspring. “Sometimes their injuries are obvious,” says Gavin Bruce, IAR’s executive director. “For instance, you can see the burns on their hands where they were clinging to their mothers.” However, many of them suffer severe organ damage that’s difficult to diagnose. “They seem to recover, and then about three months later, they crash. It’s really quite traumatic.”
The Work of IAR
International Animal Rescue (IAR) Costa Rica began as a partnership with Refuge for Wildlife, an organization founded over 20 years ago to protect Costa Rica’s wildlife. Several years ago, they merged into one and continued the work that Refuge for Wildlife’s founder, Brenda Bombard, began: rescuing and rehabilitating monkeys electrocuted by uninsulated power lines. Over the years, IAR has rescued thousands of primates. They’ve also worked directly with local communities to fund the purchase of materials to insulate transformers and try to solve the problem together. However, the installation is up to the electric companies.
“Obviously, we don’t expect companies to rip out entire systems and start again,” says Bruce. “That’s unrealistic. But where there are hotspots that are especially harmful to wildlife, we ask that these get dealt with and fixed.”
For a power line to be safe, its wire must be insulated in a thick, black or gray coating. Uninsulated wires are thin and gray, with no coating whatsoever. By default, most of Costa Rica’s power lines and transformers have been uninsulated, with no official mandate to do otherwise.
Through the collaborative efforts of IRA’s Stop the Shocks program, which creates a safer habitat for the country’s wildlife by implementing solutions to end electrocutions, and the Costa Rican Institute of Electricity (ICE), the country’s state-run electrical service provider, most of the wires within Costa Rica’s Playa Nosara area were replaced with insulated cables many years ago. But for the rest of the country, there’s still a pretty long way to go.
A Landmark Decree
Titled the “Officialization of Instruments for the Prevention and Mitigation of Electrocution of Wildlife by Power Lines in Costa Rica,” Decree No. 44329-MINAE is considered a landmark initiative. Its passage in January 2024 means that companies are now required to undertake comprehensive assessments for new installations of power lines and transformers, preventing ecosystem fragmentation and loss of biodiversity in the process. The decrease stresses the need for constructing wildlife crossings to make passage safer for wildlife and also highlights the need to reduce, prevent, and mitigate instances of wildlife electrocution.
“This is a positive step,” says Bruce, “but it’s all about implementation and enforcement.”
“Costa Rica’s public services have historically been a state monopoly,” says Francisco Sánchez Murillo, IAR’s veterinary director, “so it’s about figuring out exactly who is responsible for enforcing this initiative and then connecting directly with those who can make a difference.”
Bruce agrees, “Unless it gets down to the guys installing the power lines and transformers, and the steps of the initiative become just a default part of their work order,” he says, “nothing—I think—will change.”
IAC will continue to work on equipping communities with the knowledge and information to report incidents when they occur and guide companies in implementing preventive measures. The overall idea is to execute individual safeguards at the rural level and to move forward in a sustainable and productive way.
The Next Right Steps
In late 2023, IAC opened its brand-new purpose-built Sir Michael Uren Wildlife Rescue & Education Center in Nosara, a state-of-the-art facility with two essential halves: a rescue center on one side, where injured wildlife is provided round-the-clock treatment such as wound cleaning, antibiotics, and burn cream, and a sort of sanctuary for the center’ long-time residents on the other to educate people about wildlife. The goal for every animal that arrives at IAR Costa Rica is to return it to the jungle as quickly as possible—although, in some cases, it’s just not possible.
“The pain and suffering of these animals, it’s preventable,” says Bruce. “It may be hard to eliminate, but we can massively reduce it.”
What’s required is taking the next right steps to do so.
Nat Hab’s 11-day Natural Jewels of Costa Rica takes travelers into the heart of this storied Central American country, where—like Martin—you can experience the calls of the howler monkeys firsthand. Learn more about the plight of these primates here.
