Power line electrocutions are no longer biggest threat to Idaho birds, Boise State study shows

Many birds found dead were protected by state and federal laws such as bald eagles, golden eagles and several species of hawks

By: - August 2, 2023 4:15 am

A Swainson’s hawk taking flight from a power pole in the Morley Nelson Snake River Birds of Prey National Conservation Area in southern Idaho. (Courtesy of the U.S. Geological Survey)

Illegal shooting along power lines is the leading cause of death for many protected bird species in Idaho and its neighboring states, according to new research from Boise State University. 

Eve Thomason, the lead author of the study and a recent graduate of BSU’s raptor biology master’s program, partnered with private, state and federal agencies to examine the leading cause of death for birds near power lines in the Western U.S. 

Between 2019 and 2022, Thomason’s research team collected a total of 410 dead birds along 120 miles of power lines in Idaho, Wyoming, Utah and Oregon.

In a phone interview, Thomason told the Idaho Capital Sun that her graduate research looks into the assumption that electrocution is the greatest threat to birds along power lines. 

The research team sent all 410 carcasses to the Idaho Department of Fish and Game Wildlife’s forensic lab for X-rays where examiners were able to determine the cause of death for 175 of them — in which 66% of those birds died from gunshot. 

Of the birds that were shot, only one of them   a pigeon   was not listed as a protected species. The remaining birds shot included bald eagles, golden eagles and several species of hawks. 

Lab results showed that most of the birds died from gunshots, while death by electrocution and collisions were split evenly: 

  • 66% died from gunshots
  • 17% died from electrocution
  • 17% died from collisions

Power lines and Idaho birds

Thomason said her interest in the topic began when she worked at a power utility company conducting risk assessment surveys on power lines. 

During that time, she noticed that there were many dead birds in areas where power lines would normally be considered safe. Upon a closer look, she noticed those birds were being shot. 

“Birds are drawn to power poles and power lines,” she said. “In our region, they’re often the tallest feature across the landscape, so this provides birds with a vantage point across the landscape. It gives birds a place to perch, hunt or nest, but this also presents some risk.”

Power lines are energized, so when a bird makes contact with two parts of a power line at the same time during take off or landing on a power pole they are electrocuted, she said.

According to the study, many bird carcasses had visible signs of electrocution such as burns and singed feathers. However, Thomason said that through X-raying each carcass, examiners found that some bird carcasses with electrocution signs also had gun pellets throughout their bodies. 

Thomason said it took a lot of collaboration to finalize the research, and she thanked local and federal partners. 

“We’ve been really lucky to have really great relationships with local, the state, federal agencies, the utilities,” she said. “We’ve learned that illegal shooting of birds on power lines is prevalent and occurs over a really big area. It’ll be vital that all these partners are part of crafting solutions.”

Illegal shootings more common than what previous research suggested, scientist says

Todd Katzner, U.S. Geological Survey conservation biologist and Thomason’s graduate adviser, told the Sun that electrocution is no longer the biggest threat to bird populations.

“The primary threat to larger birds that are perched on power lines is going to be illegal shooting,” Katzner said.

Previous research suggested that birds were getting electrocuted with regular frequency along power lines, he said. And since then, utility companies such as Idaho Power have taken steps to mitigate bird electrocution. 

“We collected an awful lot of dead birds, and a huge proportion of them had been shot illegally,” Katzner said. “As scientists and as humans, we tend to think of this type of behavior as occasional and rare, and what we’re finding is that it’s much more common than we previously experienced.”

Katzner said that while there are efforts to mitigate electrocution and collision, this research highlights how there are not as many ways to mitigate illegal shootings. 

Funding for this research was provided by the Idaho Army National Guard, Avian Power Line Interaction Committee, U.S. Fish and Wildlife Service, Bureau of Land Management, the Raptor Research Center at Boise State University, and the U.S. Geological Survey. 

The study, “Illegal shooting is now a leading cause of death of birds along power lines in the western USA,”  was published in the journal iScience. To read, click here

Correction: This story was updated to reflect that examiners were able to determine the cause of death for 175 birds. 


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Mia Maldonado
Mia Maldonado

Mia Maldonado joined the Idaho Capital Sun after working as a breaking news reporter at the Idaho Statesman covering stories related to crime, education, growth and politics. She previously interned at the Idaho Capital Sun through the Voces Internship of Idaho, an equity-driven program for young Latinos to work in Idaho news. Born and raised in Coeur d'Alene, Mia moved to the Treasure Valley for college where she graduated from the College of Idaho with a bachelor's degree in Spanish and international political economy.