What is the issue?
It is currently estimated that around 6.5 million migratory birds collide with communication towers in the United States annually.
Communication towers transmit signals such as radio, TV, cellular, microwave, paging, messaging, public safety, wireless data, and emergency broadcasting. They are built to meet the needs of the industry, ensuring that “line of sight” communication signals are not blocked by trees, topography, or buildings, while minimizing development costs. Therefore, towers can be some of the tallest human-made structures on the landscape.
Currently, there are an estimated 160,000 registered communication towers (this estimate only includes towers taller than 200 feet above ground level) in the U.S., with numbers expected to increase to meet societal needs.
The Service’s Migratory Bird Program first focused in detail on the growing problem of bird collisions with communication towers after a large, single-night kill of between 5,000-10,000 Lapland Longspurs and other songbird species at 3 towers in western Kansas in 1998.
Since then, we have taken several steps in partnership with experts and key federal agencies, including the Federal Communication Commission (FCC) and the Federal Aviation Administration (FAA), to develop and implement actions that help avoid and minimize impacts to migratory birds from towers and other tall tower-like structures.
Why does this happen?
We do not definitively understand why bird mortality occurs from communication towers. However, available literature suggests the risk increases when towers:
- Use steady burning lights;
- Have guy wires for support;
- Are taller than 350 feet;
- Are located in areas with frequent inclement weather patterns;
- Are placed in areas with higher density of migrants using the airspace; and
- Are located along ridgelines, effectively reducing the free airspace above the tower.
Night-migrating songbirds are either attracted to or disoriented by obstruction warning lighting systems, especially during overcast, foggy, or other low visibility conditions. Birds congregate in larger numbers at towers with steady burning lights compared to those with flashing lights; although birds congregate at flashing lights during the “on” phase and disperse during the “off phase”. In addition, lighting on associated infrastructure (e.g., buildings (1.8MB), parking lots, etc.) can also attract birds to the tower area.
What are some solutions?
To reduce the risk of bird collisions with towers, the Service developed Recommended Best Practices for Communication Tower Design, Siting, Construction, Operation, Maintenance, and Decommissioning (235.7KB). This document targets measures to help avoid and minimize impacts from some of the primary identified structural and location causes of tower impacts, while also addressing the potential habitat impacts to birds associated with tower construction.
The Service works closely with the Federal Communications Commission (FCC) and the Federal Aviation Administration (FAA) to ensure that lighting and communication tower development and maintenance practices continue to work toward avoiding and minimizing impacts to migratory birds.
In a recent important development for reducing bird impacts from communication tower lighting, the FAA released its latest Advisory Circular requiring more bird-friendly lighting systems on new towers and encouraging bird-friendly lighting systems on existing towers. The FCC's Opportunities to Reduce Bird Collisions with Communications Towers While Reducing Tower Lighting Costs (50.2KB) offers guidance for tower owners on applying the new standards, which also have the benefit of reducing construction and maintenance costs. To learn more about the new lighting standards see the Communication Tower Lighting Fact Sheet(204.1KB).
Material on this webpage was sourced from: Avery et al. 1976 (253.6KB), Ball et al. 1995 (309.5KB), Cochran and Graber 1958 (198.4KB), Erickson et al. 2005 (256.2KB), Evans et al. 2007 (2.8MB), FCC 2012, Gauthreaux and Belser 1999 (27.2KB), Gauthreaux and Belser 2006 (891.6KB), Gehring et al. 2011 (135KB), Larkin and Frase 1988, Longcore et al. 2012 (2.8MB), Longcore et al. 2012a, Manville 2014, Pascual 2006, Patterson 2012 (1.1MB), Poot et al. 2008.