Broad-tailed Hummingbird perches on a branch.
Broad-tailed Hummingbird. Photo: Evan Barrientos/Audubon

Frequently Asked Questions

Q: What is the Lights Out program?

A: Lights Out, a national effort to reduce bird collisions due to reflective surfaces and disorientation due to bright artificial lights, is a partnership between the National Audubon Society and the International Dark-sky Association (IDA). To learn more about Lights Out programs happening across the country, explore Audubon’s existing Lights Out Programs.

Q: What is Lights Out Colorado?

A: Lights Out Colorado targets skyglow in Colorado.  Coordinated by the Colorado chapter of the International Dark-sky Association, Audubon Rockies, and Denver Audubon, this effort endeavors to raise awareness and motivate actions that make night skies safer for passage of migrating songbirds.  See our videos for more about bird migration and light pollution in Colorado. 

Q: What is Lights Out Denver?

A: Lights Out Denver is an initiative of the City and County of Denver in partnership with Denver Audubon. As part of Denver’s commitment as an Urban Bird Treaty City, this volunteer program aims to help local businesses save energy, money, and migratory birds by promoting bird-safe buildings and reducing nighttime lighting.

Q: What is light pollution and how does it harm birds?

A: Light pollution is the excessive use of artificial light. Components of light pollution include:

  • Glare – excessive brightness that causes visual discomfort

  • Skyglow – brightening of the night sky over inhabited areas

  • Light trespass – light falling where it is not intended or needed

  • Clutter – bright, confusing and excessive groupings of light sources

For nocturnal migrants, skyglow can attract and disorient birds during their nighttime travels. This disorientation can cause bird fatalities or lower survivorship and reproductive ability as these birds expend already limited energy resources circling and calling out in confusion. The exhaustion can leave them vulnerable to other urban threats, including predators. 

Q: When do most birds migrate through Colorado?

A: The majority of nocturnal migrants pass through Colorado spaces and skies from April through May and August through September.

Q: How can I reduce my light pollution impact?

A: There are a variety of ways that individuals can help birds during their night migrations, and all year-long. This includes turning off outdoor lighting during key migration periods (April-May; September-October) and adjusting necessary outdoor lighting to minimize their harm.

Specific actions you can take for exterior lighting:

  • Turn off exterior decorative lighting

  • Ensure your outdoor lights aim down and are well shielded

  • Use reflective paints or self-illuminous markers for sign/curbs/steps instead of lights

  • Reduce atrium lighting wherever possible

  • Install automatic motion sensors/controls and dimmers

  • Choose warm bulbs (3,000 degrees Kelvin or less) when converting outdoor lights to LED

  • Determine the necessity for new lighting (quality/quantity)

Specific actions you can take for interior lighting:

  • Turn off interior lighting especially on higher stories

  • Use direct lighting (i.e. lamps) for workers staying late or pull window coverings

  • Install automatic motion sensors/controls and dimmers

Finally, please share this information with family, friends, local businesses, and governments. Together we can build caring, bird friendly communities.

Q: How can I get involved?

A: Pledge to turn off lights during peak spring and fall migration months and take other Lights Out steps by visiting the How You Can Help page.   

Q: What other benefits are there to participating in the Lights Out Colorado program?

A: Energy and cost savings, reduced light pollution for night sky enjoyment, decrease in CO2 emissions, and a healthier environment for all.

Q: How can I monitor bird migration?

A: Scientists can use NEXRAD radar to monitor and predict migratory bird movements in real-time. Scientists have used this data to create a user-friendly migration prediction service, known as CSU’s Aeroeco Lab. Community members can also monitor migration alerts for states and cities.  

Q: What is CSU's Aeroeco Lab? What is BirdCast?

A: Colorado State University’s Aeroeco Lab is affiliated with BirdCast and it’s part of CSU’s Department of Fish, Wildlife, and Conservation Biology.  The Aeroeco Lab applies weather surveillance radar to gather information on the numbers, flight directions, speeds and altitudes of birds aloft in order to expand the understanding of migratory bird movement. The migration forecast maps show predicted nocturnal migration three hours after local sunset.  CSU’s Professor Kyle Horton is the co-author of the national bird migration forecast.  On the Aeroeco Lab site it’s possible to drill down to see the forecast for the state of Colorado. 

There’s also a live NEXRAD Radar map at

BirdCast is a joint effort by The Cornell Lab, Colorado State University, and UMass Amherst.  Colorado State University and the Cornell Lab of Ornithology currently produce these forecasts. At BirdCast you can view live radar-based bird migration maps.  BirdCast also has the same national bird migration forecast and alerts as the CSU site.  

Q: How can I reduce window collisions by birds?

A: Reducing window collisions can be achieved by creating patterns on reflective glass surfaces (quantity and spacing matter: multiple markings 2 to 4 inches apart are recommended), install external screens on windows, close blinds or curtains, move plants away from windows, place bird feeders directly on windows.

Q: What window treatments are recommended to prevent collisions?

A: There are multiple treatments on the market, however, the American Bird Conservancy recommends products to retrofit existing windows for homeowners.

Q: How can I participate in community science by helping track bird mortalities?

Community scientists can be a major help in tracking bird mortalities and causes by using dBird.org, an online crowd-sourced data collection tool.  dBird provides a way for the public to report incidents of dead and injured birds, to guide research and advocacy efforts that aim to reduce human-caused hazards to birds. 

Residents of Denver can email info@denveraudubon.org to volunteer to help collect dead bird statistics in Denver. 

Q: What other ways can I make my community bird-friendly?

A: By simply choosing native plants for our yards and public spaces, we can restore vital habitat for birds in our communities and help them adapt and survive in the face of climate change. Audubon Rockies’s Habitat Hero program is designed to enable anyone to have a positive impact by planting for birds, right where they live.

And don’t forget to encourage others to help migrating birds!