A bird’s eye view of Capitol Hill at night (Image: CHS)

Despite sirens, airplanes, and the overall hum of the city, it is still possible to hear them traveling overhead at night. Not every bird calls during migration, but I expect to hear the thin “seeps” of sparrows and plaintive whispers of thrushes when I step outside on an ideal night in the spring or fall. The weeks between the end of September and just about now are peak travel times for birds pouring south for their wintering grounds. The night before writing this, around 300,000 birds moved over King County.

On a good night, with a full moon, you might even be able to peer at it with binoculars and catch a few birds passing by. One time I caught a small heron, probably a Green Heron, highlighted by a full moon. But that’s not how an estimate of migrating birds happens. In this case I logged into an incredible new website called BirdCast, which uses weather, radar, and a big ol’ heap of machine learning and big data to both forecast and understand migratory patterns of birds.

The Birdcast Dashboard from 10/13/2022

This is a piece of a puzzle that I have been thinking about lately. Recently, with the prompting of Seattle Audubon, Mayor Bruce Harrell signed the Bird-safe Seattle Week proclamation, full of encouraging statements, but ones with no laws underscoring them (yet). However, it’s a start, getting the rest of Seattle to stand up and take notice of how we actually impact the natural world around us. And as Urban Conservation Manger Joshua Morris puts it: “this is intended to be a stepping stone into Mayor Harrell’s office.”

One phrase sticks out to me in the proclamation: “bird-safe buildings.” Broadly this means having guidelines, or even laws, for buildings that reduce impacts on all birds. This includes but is not limited to reducing their risk of confusing birds with reflective surfaces that result in strikes, and reducing the amount of light pollution they emit. That last bit feels especially relevant as we stare down a long dark winter: light pollution is both a sneakily pervasive and corrosive environmental impact.

Most birds that migrate long distances, with a few notable exceptions like birds of prey, migrate at night. This is an important context for why light pollution matters the most during this time of year.

Bird-safe Seattle Week didn’t spring up at a random time on the calendar, it was chosen because this is a peak point during migration. A time when birders can expect to see more birds moving through the Hill and across our entire region. The Seattle Bird Collision Monitoring Project is active during this period of time as a direct result, using the newer community science website dBird, to log the dead birds they find in their surveys of several buildings in Seattle 5 of which are on the Hill. (Found a dead bird? You can easily contribute via dBird and help.)

Light pollution, or artificial light at night (ALAN), is really hard on birds. I’ve been pretty emphatic about how amazing migration is regularly in my writing here, and similarly adamant about the outright challenges birds face when migrating, regardless of the barriers we put in the way. There are estimates that between 100 million and 1 billion birds are killed by light pollution each year in the US. That’s too much.

A map of light pollution across the U.S.

Toronto’s FLAP, or Fatal Light Awareness Program, was the first organization to raise the alarm in 1993. The idea of Lights Out campaigns followed in 1999, when the National Audubon Society started their first program in Chicago. Since then, Lights Out programs have grown across the country working to raise overall awareness and specifically to reduce light pollution at targeted periods when bird passage is highest. These campaigns have proven their worth, convincing building managers to alter and turn off their lights. Two notable examples are the work NYC Audubon did to reduce the impacts of the 9/11 memorial and Houston Audubon’s work to get skyscrapers to turn off the lights during migration.

What’s striking is that Seattle, despite our emphasis on the environment, we haven’t had any emphasis on this until recently. Seattle Audubon’s Lights Out Pledge is the first, vital step but it’s not enough. Compared to cities across the Eastern US, we’re way behind the times.

Taking a step back: why is ALAN so hard on migrating birds? By migrating at night, birds are doing several things: they are using celestial cues to navigate, they are avoiding aerial predators that are active during the day, and they are giving themselves the opportunity to stop and refuel during the day. Not only does ALAN (apologies to all the Alans out there) make it harder for migrating birds to see and properly interpret the night sky they’ve used to navigate for thousands, if not millions, of years but it confuses them. Birds are drawn in by light pollution, which at best exhausts them and makes their journey harder. At worst it results in birds striking buildings.

Obviously the simplest solution to this is just turning out lights. Even within a smaller scope of Capitol Hill, it might be hard to imagine less lights on, but Lights Out programs don’t expect every light to go out either. A reduction makes a big impact, especially in taller buildings. And before you clutch your pearls and start talking about crime in a darkened city: there’s research that suggests the jury is still out on whether excess lighting actually reduces crime (and in some cases might increase it).

Lights over 520 where it crosses the Arboretum. (Image: Brendan McGarry)

Beyond migrating birds, there is an exhausting pile of evidence telling us that ALAN is bad for us and pretty much every organism researchers have studied. Migrating birds might be dying by the truckload, and those that make it might get tricked into breeding too early when they show up on a breeding territory. Amphibians breed less and are more susceptible to parasites and other pollution. Approximately half of all insect species are nocturnal, and a third of those attracted to your porch light die of predation or exhaustion. ALAN has been demonstrated to entirely alter the plant communities within an ecosystem and while our street lights don’t support photosynthesis they can confuse street trees into growing larger leaves with more stomatal pores. This makes trees more susceptible to drought and climate change. Despite being able to pull down the blinds at night, human health is also impacted with evidence of higher instances of cardiovascular disease, depression, and sleep disorders (ALAN also impacts communities of color, the elderly, and lower income households more).

Ok, so you get it ALAN is bad. (“Bad ALAN!”) So what do we do about it?

Here’s the good news: there are a lot of simple things to do to reduce impacts. Shielding lights so they aren’t just spraying all over the place, is a simple option. Paying attention to the spectrum and (color) temperature is important too – though with the diversity of life considered it’s not quite a one size fits all situation, lights that are warmer colored are best. Then consider how bright they are: unless you are doing open heart surgery on your front porch, you probably don’t need lighting that blinds you whenever you look at it. And maybe you only need a light on when you pass by – timers and motion sensors are great solutions.

Some ways to reduce ALAN impacts. Credit: Darksky.org

I tend to get a bit frustrated when individuals are encouraged to solve environmental problems by being conscious consumers. We might reduce our personal light “footprint” while our neighbors use industrial light arrays to take their dog out to pee, and those billboards around town are on all night. However, this is one of those things that we all need to do. Darkness is habitat, and the reduction of it, even in our little yards, is a loss of habitat. Certainly we need to enact laws and tell everyone else (which is what Seattle Audubon is working on as you read this), but a little bit of personal action goes a long way in this case. If you are still rolling your eyes and saying this is pointless with all the other issues out there, maybe you care more about money: These solutions can reduce your utility bills and there are state rebates for more efficient lighting.

If you are interested in learning more, here are some resources to help you along:

• Dark Sky Friendly Home Lighting Program
• Rapid Assessment of Lamp Spectrum to Quantify Ecological Effects of Light at Night (read about what this stuff means here)
• National Audubon Society’s Lights Out

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