To prevent sandhill cranes from colliding with power lines as they fly to roosting sites, scientists at EDM International mounted UV lights on power lines’ supporting structures and shined the lights on the lines at night. The Avian Collision Avoidance System (ACAS) shines UV lights on power lines to prevent collisions by sandhill cranes. Courtesy of James Dwyer, EDM International. EDM tested the effectiveness of its system, called ACAS for Avian Collision Avoidance System, in 2018 at Nebraska’s Iain Nicolson Audubon Center, a key habitat for migrating sandhill cranes. The team used a randomized design to test collision mitigation effects of a pole-mounted near-UV light (UV-A; 380 to 395 nm) ACAS used to illuminate a 258-mile power line crossing the Central Platte River. The scientists observed 48 sandhill crane collisions and 217 dangerous flights of sandhill crane flocks during 19 nights when the ACAS was off, but just one collision and 39 dangerous flights during 19 nights when the ACAS was on. Based on these observations, the team documented a 98% decrease in collisions and an 82% decrease in dangerous flights when the ACAS was on. Conventional line markers were already in place on the power lines, and the researchers speculate that the ACAS illuminated these markers, making them easier for the birds to see. The team is testing how effective the ACAS will be on wires that do not have line markers. Sandhill cranes are at risk of colliding with power lines as they approach their roosting sites at dusk. Courtesy of James Dwyer, EDM International. “I hope to see the ACAS applied to and studied on other power lines and on communication towers to identify whether it is as effective with other species, habitats, and wire configurations,” said James Dwyer of EDM International. “From there, if the ACAS proves broadly effective, I hope to see it made easily available to the global electric industry.” Midflight collisions with power lines affect 12 of the world’s 15 crane species, including one critically endangered species, three endangered species, and five vulnerable species. The research was published in The Condor: Ornithological Applications (https://academic.oup.com/condor/article-lookup/doi/10.1093/condor/duz008).