Let there be Night: How light pollution harms migrating birds

Alison Robey
If last month’s solar eclipse taught me anything, it’s that we all still love seeing cool stuff in the sky. I don’t think we realize how fast astronomical wonders are fading out of sight: studies show that our night skies grow about 10% brighter every year, and the number of visible stars plummets as a result. At this rate, someone born 18 years ago to a sky with 250 visible stars would now find only 100 remaining.
Vanishing stars may feel like just a poetic tragedy, but as I crouch over yet another dead Wood Thrush on my morning commute, the consequences of light pollution feel very real. Wincing, I snap a photo of the tawny feathers splayed around his broken neck on the asphalt.
It’s not the only such photo I’ll take this year. The building whose towering windows took this thrush’s life is infamous; like many other passersby, I pay close attention to the ground around such spots to record any victims. We upload our morbid photography to iNaturalist, an app usually reserved for more cheerful records and identifications of flora and fauna, where they automatically join several citizen science projects focused on bird-window collisions.
Why the macabre gallery? These collections provide concrete evidence of just how many birds windows kill. Ideally, that information encourages tactics to reduce casualties, like lobbying homeowners and institutions to add decals or screens to their glass.
Though such measures are critical for limiting window strikes during the day, we often overlook the damage our windows cause at night. Remarkably, most bird migration actually occurs by moonlight; if you stand under the stars and listen during migration — which began in earnest last week — an audible chorus of chirps and buzzes overhead indicates a sky full of birds.
Birds evolved to fly under the cover of darkness for many reasons. Nightly travel means they can spend the bright, bug-filled days gathering food. Darkness helps migrants avoid predators, and the lower turbulence and cooler temperatures of nighttime skies allows for more energetically efficient flights.
Though the specifics of nocturnal navigation are a longstanding ornithological mystery, that navigation is undoubtedly disrupted by the growing brightness of the night sky. Bright lights disorient the birds’ sense of direction and attract them towards the light sources themselves. In that state of confusion, nocturnal window strikes skyrocket.
In the U.S., one billion birds die each year by flying into windows. Distinct behavioral changes around brightly lit structures are the main cause of mortality: the usual conversation of nocturnal flight calls grows into a confused cacophony. Those that avoid collisions face different risks: the energy they waste investigating unfamiliar lights means they’ll have a harder time avoiding predators, catching enough food, and reaching their final destinations.
The harm caused by light pollution is not limited to birds. Even in rural areas, many nocturnal animals struggle to adapt to brightening nighttime environments: bats can’t fly efficiently, amphibians can’t reproduce normally, and insects can’t forage effectively.
Humans aren’t immune either. Brighter nights disrupt our sleep cycles — something I can personally attest to, as someone who grew up in Kent and now struggles nightly with the brightness of New Haven — and are associated with a slew of negative health effects. And though people widely associate more lights with greater safety, evidence of this is mixed.
Despite the repercussions, the reach and severity of light pollution keeps growing. Electricity usage in the U.S. is on the rise again; while much of that energy has more intensive uses, the U.S. Energy Information Administration estimates that 6% of residential and 17% of commercial energy is all for lighting.
As disheartened as I am by increasing energy usage and vanishing stars, by unnecessary lights glaring from empty sports fields or barren storage facilities, and by dead songbirds on my morning commute, there is a silver lining to this story. Fixing most pollution problems — microplastics, oil spills, atmospheric CO2 — requires complex, intractable solutions. Light pollution, on the other hand, is completely, immediately, effectively reversible.
This is a critical time of year to make that change. The transition from April to May brings spring rains, bursting tree buds, and a deluge of migrating birds: cheerful songs of Yellow Warblers, gleaming feathers of Scarlet Tanagers, playful flights of American Redstarts. You can watch these migrants gather above your home like a rising storm using BirdCast, Cornell Lab of Ornithology’s avian version of a weather radar.
The closer that storm comes, the more important it is to flip those light switches off. Simple steps, like limiting the use of aesthetic lighting, keeping the beams of necessary lights targeted, dim, and warmly colored, or curtaining bright windows, make all the difference to our birds. Participating in darkening the skies this spring will help keep these little travelers aloft — and maybe bring some stars back into view, too.
Alison Robey is a writer for the Kent Land Trust, a volunteer at the Sharon Audubon Center, and a third-year PhD candidate in Ecology & Evolutionary Biology at Yale University.
Join The Lakeville Journal for a community celebration, featuring local nonprofits and businesses, festive family fun, great food, and engaging activities.
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See you at the Lakeville Journal Street Fair!
If you have any questions, please email streetfair@lakevillejournal.com
Cobbler n’ Cream
5 to 7 p.m.
Freund’s Farm Market & Bakery | 324 Norfolk Rd.
Canaan Carnival
6 to 10 p.m.
Bunny McGuire Park
Canaan Carnival
6 to 10 p.m.
Bunny McGuire Park
Cocktail Party
5 to 7 p.m.
Douglas Library | 108 Main St.
Canaan Carnival
6 to 10 p.m.
Bunny McGuire Park
Boot Drive
8 a.m. to 2 p.m.
North Canaan Fire Co. | 4 E. Main St.
3rd Annual Fly-In
8 a.m. to 3 p.m.
Triumph Airfield | 547 W. Main St.
Canaan Railroad Station Museum
10 a.m. to 6 p.m.
Canaan Union Station
New England Accordion Connection
9 a.m. to 8 p.m.
Canaan Union Station
Canaan Carnival
3 to 10 p.m.
Bunny McGuire Park
Berkshire Resilience Brass Band
5 to 8 p.m.
Canaan Union Station
Barbecued Chicken Dinner
5 to 7 p.m.
St. Martin of Tours | 4 Main St.
Canaan Fireman’s parade
6 p.m.
Rosa setigera is a native climbing rose whose simple flowers allow bees to easily collect pollen.
After moving to West Cornwall in 2012, we were given a thoughtful housewarming gift: the 1997 edition of “Dirr’s Hardy Trees and Shrubs.” We were told the encyclopedic volume was the definitive gardener’s reference guide — a fact I already knew, having purchased one several months earlier at the recommendation of a gardener I admire.
At the time, we were in the thick of winter invasive removal, and I enjoyed reading and dreaming about the trees and shrubs I could plant to fill in the bare spots where the bittersweet, barberry, multiflora rose and other invasive plants had been.Years later, I purchased the 2011 edition, updated and inclusive of plants for warm climates.
On the cover of the new edition, a quote from Adrian Higgins of The Washington Post boasts, “Michael Dirr is the oracle of ornamental horticulture. I trust his judgements implicitly.”I heartily disagree with Mr. Higgins:I blame this book — and my poor use of it — for some of my worst tree and shrub choices.
I realize some readers might find this declaration inflammatory. The book still occupies a place of high regard among experienced and novice gardeners alike, so please allow me to explain.
In addition to giving the reader his opinion on the aesthetic worthiness of the woody plants included in the book, Mr. Dirr makes good on the book’s title with a review of each species’ hardiness. What makes a tree hardy?It thrives in its intended site, resisting disease with leaves and bark not readily eaten by insects and other critters.
Non-native plants make up the majority of the recommended hardy plants in the book.And here is why:Native trees and shrubs are, by evolution’s design, food source and host to our native fauna — critters large and small. There is no substitute equal to the fauna’s co-evolved flora.A native caterpillar cannot eat a kousa dogwood leaf, as it has not evolved to digest it.Non-native plants seemingly have the advantage if the lens we look through values pristine, uneaten leaves.
In the days when there were sufficient thriving ecosystems to maintain local habitats, a non-native specimen tree here and there was just fine.But where we live in Northwest Connecticut, our woods, meadows, marshes and other natural areas have, for a couple of decades, been severely compromised by invasives that have almost entirely removed the food sources for native insects. It is up to us — now — to plant native plants to save the food chain.Without insects, not only will native animals die, but human food sources will also be at risk.
The security of our food pipeline seems a worthy exchange for some caterpillar-eaten leaves — and to be clear, we’re not talking about non-native infestations such as spongy moth, but rather native caterpillars, which are the singular food source for nesting birds.
My issue is that, in being a trusted source for plant selection, Dirr’s book should give equal — if not prioritized — space to information on ecological impact.For example, it would be good to know when selecting a tree, that a native oak provides food and other ecosystem services to more than 400 native animal species, while a native tulip poplar supports fewer than 30 — though that includes the Eastern tiger swallowtail. Including information on the birds and insects attracted to a given plant would enable reader to weigh these factors in choosing what to grow.But this information is not mentioned at all.
Dirr makes no mention of the role some of these plants have played in the degradation of our natural areas — an omission that is highly relevant, as many of the plants featured in his book are, in fact, invasive culprits. Plants like barberry, porcelain berry and tree of heaven are showcased for consideration alongside native plants without recognition of the devastating infestations they can manifest. Tree of Heaven is now responsible for hosting the spotted lanternfly, which is devastating crops.
Similarly Euonymous alatus (winged euonymous) and Actinidia arguta (hardy kiwi) — two highly invasive plants touted in the book — have been banned or are close to being banned for sale from nurseries in the state of Massachusetts. To his credit, Dirr does point out the invasive nature of Ligustrum sinense (Chinese privet), calling it “a terrible and devastating escapee that terrorizes floodplains, fencerows and even open fields, reducing native vegetation to rubble.” Yet Japanese honeysuckle gets an understated warning, with Dirr describing this massively invasive shrub as “bullying their way into understory and open areas.”
The latest edition of Dirr’s book devotes seven pages of copy and photos to various Berberis species, about which Dirr waxes poetic. He notes the addition of “30 new cultivars” in the latest revision and complains that “this species is under assault for its aggressive invasive nature.” He refers to Berberis thunbergii — Japanese barberry, the most invasive of them all — as “the species of major importance in garden commerce.” This plant has already been outlawed for sale in New York, Pennsylvania, New Hamphsire and Maine.A few weeks ago, a bill was passed in Connecticut recognizing the harm of a broad group of invasive plants. Under this new legislation, barberry will be phased out from sale or transport by October 2028.
In understating the invasive nature of many non-natives and de-prioritizing the importance of native species, Dirr’s widely used reference may be partly responsible for many a devastated woodland, forest, meadow and marsh in New England — if not across the U.S.Certainly, the evolution of species, and scientific knowledge about the environment, is changing faster than new editions of books can be printed. I can only hope that if a new edition of Mr. Dirr’s reference book is in the works that it will account for this criteria we now know to be vital in plant selection.
Which brings me back to that quote on the cover from The Washington Post and the larger issue it suggests:Should “ornamental horticulture” get a pass when it comes to ecological survival?I think we can agree — it should not.The consequences are simply too destructive.
Dee Salomon ‘ungardens’ in Litchfield County.
Foxtrot Farm & Flowers’ historic barn space during UAW’s 2024 exhibition entitled “Unruly Edges.”
Art lovers, mark your calendars. The sixth edition of Upstate Art Weekend (UAW) returns July 17 to 21, with an exciting lineup of exhibitions and events celebrating the cultural vibrancy of the region. Spanning eight counties and over 130 venues, UAW invites residents and visitors alike to explore the Hudson Valley’s thriving creative communities.
Here’s a preview of four must-see exhibitions in the area:
1. Wassaic Project (37 Furnace Bank Road, Wassaic)
“So It Goes” is a powerful group exhibition curated by Eve Biddle, Bowie Zunino, Jeff Barnett-Winsby, and Will Hutnick. The title, drawn from Kurt Vonnegut’s “Slaughterhouse-Five,” signals a reckoning with how we process the horrors of the world. Through play, reflection, and immersive scale, 43 artists respond with urgency and imagination. Installations can be seen throughout the town of Wassaic at Maxon Mills, Gridley Chapel, and Luther Barn, each space transformed by this deeply thoughtful show.
2. Foxtrot Farm & Flowers (6862 Route 82, Stanfordville)
“Queer Bestiary,” a group show curated by Charlotte Woolf, is inspired by Patricia Ononiwu Kaishian’s book “Forest Euphoria.” The exhibition investigates queer ecology and human relationship to land through the work of 10 artists using painting, sculpture, textiles, and photography. The exhibit is accompanied by a variety of interactive experiences including tattoo pop-ups, karaoke, book readings, and pick-your-own flowers.
3. ChaShaMa North/ChaNorth (2600 Route 199, Pine Plains)
ChaShaMa North (ChaNorth) will have open studios all weekend and has partnered with Paradice Palase, a platform for emerging artists, to mount a site-specific sculpture exhibition featuring 20 artists entitled “Alone, You Are Heard.” On Saturday evening, July 19, stop by for Weird Music Night for an audio-visual synthesis of experimental music, performance art, and unexpected happenings. Don’t miss this opportunity to experience an eclectic lineup of acts that redefine the boundaries of performance.
4. Millbrook Arts Project(3 Friendly Lane, Millbrook)
The Millbrook Arts Project is hosting a curated exhibit entitled “Generated Utility” at the newly renovated gallery at the village library. The exhibit will feature the work of artists Natalie Beall and Kathy Greenwood. Additionally, visitors will have access to 12 open artists studios across town. The weekend culminates in a free outdoor concert on Saturday evening at 6 p.m. at the Millbrook Bandshell. Enjoy the Indie-Folk sounds of Strawberry Runners and She Keeps Bees.
For more information and a complete list of participating artists and locations, visit: upstateartweekend.org