April 4, 2023

Celebrating Dark Skies During Spring Migration

Cooper Farr, Director of Conservation, Tracy Aviary

On the evening of Thursday, April 6th people will head to Tracy Aviary ...

to celebrate the annual Lights Out Salt Lake event, planned every year during spring bird migration. Many people don’t realize that most birds that migrate do so at night. It isn’t something we think about as we lie in bed, but on any given spring night there could be hundreds, or even millions of birds flying high above us through the dark sky.

Birds migrating

Photo credit: Birds migrating, Maksim Shutov (Unsplash)

During spring, an estimated 3.5 billion birds will cross the U.S./Mexico border as they head north to their breeding grounds. Many of these birds will migrate through Utah, and the April 6 Birds and Brew: Lights Out event, co-hosted by Audubon Rockies and Tracy Aviary, is a way to spread the word about a simple way to make their journey safer: turning out and shielding nighttime lights.

American goldfinch and Chipping sparrowsDark-eyed junco

Photo Credit: American goldfinch, Chipping sparrows, Irene K (Pixabay); Dark-eyed junco, Anish Lakkapragada (Unsplash)

As these birds fly over Salt Lake City, they will encounter a blindingly bright landscape below, where nighttime lights will draw them into the urban environment. Unable to perceive glass, many birds collide with windows before they can find their way back out of the city. Nearly 988 million birds die from crashing into windows in the U.S every year. Window collisions happen for a variety of reasons – not just when light pollution draws birds off course – and it is a huge problem for birds around the world.

Community Science in Action

The negative relationship between light pollution and migratory birds has been documented by many studies around North America, but this issue was previously understudied in the Intermountain West and Utah. To fill this data gap, in partnership with the Salt Lake Chapter of the International Dark Sky Association (now encompassed in the statewide Utah chapter), Tracy Aviary launched the Salt Lake Avian Collision Survey (SLACS) in spring of 2017. For this project, volunteers walk downtown survey routes during spring and fall. They search the areas around buildings in 20 city blocks of downtown Salt Lake City looking for birds that have collided with buildings. Once a bird is found, the species and location is documented, and the bird is collected and donated to the Natural History Museum of Utah for further research and to display in their collection.

Wilson’s Warbler collision victim documented during Salt Lake Avian Collision SurveyLights Out Salt Lake yard sign

Photo Credit: Cooper Farr, Wilson’s Warbler collision victim documented during Salt Lake Avian Collision Survey;
Lights Out Salt Lake yard sign

Since the project began in 2017, sixty-one volunteers have conducted over 1,090 surveys, documenting 258 bird-window collisions of 50 different bird species. This number represents a small fraction of the birds that likely collide with windows in the area, considering the surveys are done intermittently during the migration season and only covers 20 city blocks. The species found most often are Western Tanagers, Brewer’s Sparrows, Dark-eyed Juncos, Orange-crowned Warblers, and Black-chinned Hummingbirds. These collisions can be easily avoided, and we’re hoping our work can help guide these efforts. Decreasing light pollution and making windows bird safe are extremely effective at mitigating window collision deaths.

Spring Migration Kickoff Event

The April 6th Birds and Brew: Lights Out kickoff event is a fun way to teach people about this very serious conservation issue, and to encourage them to participate in the Lights Out Salt Lake initiative by turning out lights at night during peak bird migration in spring and fall. With fun activities about dark skies, tabling and talks about the impacts of light pollution on wildlife and people, and food and beer to celebrate the beginning of spring migration, Tracy Aviary and Audubon Rockies hope the event will inspire Utahns to appreciate and protect the dark night sky in a whole new way.

Tracy Aviary’s Birds & Brew Spring Migration flyer

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