A study by the Cornell Lab of Ornithology found that, since 1970, the North American bird population has had a net decline of approximately 3 billion birds, a 29% drop. This finding prompted the research team to declare a "biodiversity crisis."
Artificial light at night (ALAN), along with habitat loss and climate change, is one of the major drivers of this decline. Numerous studies, even one dating back to 1996 by the World Wildlife Fund Canada and Fatal Light Awareness Program, have attributed ALAN to bird deaths. Of the birds affected, migratory birds are hit particularly hard as most migrate at night. A study published in The Condor attributes many of the 100 million to 1 billion bird deaths from collisions to be due to ALAN attracting them to fly into buildings. This does not even include the many more birds that die from exhaustion after being confused by ALAN. Birds disoriented by ALAN fly around lights for hours before eventually passing out. A notable example of this is during the annual 9/11 memorial where there can be around 16,000 birds flying above the floodlights, as reported by a New York Times article.
AB-38, a bill in the California legislature, will work to decrease light pollution, preventing the deaths of millions of birds. A study in Chicago found that reducing ALAN by half would prevent 60% of collision deaths. Because California is part of the pacific flyway, an important migratory path, AB-38 would have as large an impact.
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