Bird Illustrations:

Can Architects Build without Killing Birds?

Despite laws to reduce bird-window strikes, building-related practices continue to decimate songbirds. Can that trend be reversed?

Architecture is overdue for a reckoning with birds, owing largely to their fatal collisions with windows, but also to a host of other threats inherent in a world built mainly for humans.

The volume of birds colliding with glass specifically has reached a level impossible to ignore, with up to a billion deadly incidents a year across North America, and roughly 230,000 in New York City alone, according to New York City Audubon. In 2021, a volunteer with that nonprofit’s Project Safe Flight program recorded nearly 300 birds lying dead or dying on the pavement in a single morning at Manhattan’s World Trade Center (WTC) complex—a place where previously 30 daily casualties was shocking. 

But while the villainy of too much glass warrants attention as an isolated flaw (it’s invisible to birds), it’s also a sign of a broader problem: that we’ve been building birds out of our lives. 

“We. . .chose to clear the original natural landscape for places to build houses; we selected the garden plants . . . among many other alterations,” writes Darryl Jones in his book The Birds at My Table: Why We Feed Wild Birds and Why It Matters (2018). “All these typical features of people-space affect the wildlife living around us,” he goes on to explain.

an illustration of the Blue Tit bird
RANGE: U.K. and Ireland
THREAT: Light Pollution
An article in the journal Current Biology reported that when they nest near streetlamps instead of in their naturally dark forest habitat, female blue tits laid their eggs nearly two days earlier.
an illustration of the sparrow bird
RANGE: North America
THREAT: Building/Window Strikes
Two types of brown-black sparrow (song and white-throated) are among the top four species most vulnerable to collisions.
an illustration of the chaffinch bird
RANGE: U.K. and Ireland
THREAT: Light Pollution
When they roost near streetlights, males among these urban garden visitors tweet their dawn song artificially early. Since the song is part of their courtship ritual, this has a serious effect on their ability to breed.

For birds, the impact of so many planning, development, infrastructure, and architectural decisions has been mounting for more than a century.

The earliest written account of a bird window-strike in North America is in 1832, recorded in a book by British naturalist Thomas Nuttall. By 1978, almost 150 years later, staff at Chicago’s Field Museum had begun an annual collection of downy little victims outside the city’s lakefront convention center McCormick Place.

That was also the year a TV show called Connecticut Profiles aired an interview with architect Philip Johnson, in which he described collisions at his Glass House:

“In the first few years the birds used to die, especially during migration, because they hadn’t been able to hear from the other birds about it. But even migratory birds have now learned,” Johnson told the interviewer, as if dead birds were a reasonable and slightly amusing trade-off for great architecture.

Since then, scientists have tied a globally declining bird population to light pollution, smog, habitat loss, and even ornamental gardening—all outcomes of humans’ vehicle-dependent, 24-hour built environment.

In focusing on just a single problem—bird collisions with glass—designers could miss an opportunity to make a meaningful shift from never considering birds to building with them in mind.

a graphic from the american bird conservancy that says collisions with buildings kill an estimated 599 million birds per year in the united states
Provided by American Bird Conservancy

“[Standards] need to change quickly. Which buildings can turn their lights out overnight? Which can host rooftop habitats?” asks Dustin Partridge, director of conservation and science for NYC Audubon, adding “It would be wonderful if one day architects could convey this information.”

Some do. In 2014, seven years before New York’s bird legislation Local Law 15, personal involvement with NYC Audubon by the spouse of a principal at FXCollaborative (then FXFowle) helped draw attention to its transformation of New York’s glass-clad Jacob Javits Center from a bird killer into a sanctuary, with bird-friendly fritted glazing and a 6.75-acre rooftop garden where birds now nest and recharge. Since then, the firm has made incorporating bird-friendly features a tenet of all its designs, applied most recently to New York’s Statue of Liberty Museum. Research on bird-collision reduction by Dan Piselli, FXCollaborative’s director of sustainability, also predates the law and informed the American Bird Conservancy’s design guide.

Piselli even frames the firm’s focus on urban projects as a step in limiting rural development to conserve pristine avian habitats. “That’s a way of approaching the bird-collision issue too,” he explains. “Thinking of [bird safety] as an area of overlap with other, greater goods.” 

a photograph of New York’s Statue of Liberty Museum with a garden and glass walls it is a bird-safe building
FXCollaborative designed New York’s Statue of Liberty Museum using principles of bird-safe design. COURTESY FXCOLLABORATIVE

At the other end of the spectrum is Dutch architect Ton Venhoeven, whose radically nature-inclusive structures have features like green roof habitats and nests built into walls. “We have to teach people that they are not the center of the universe,” he says. 

Anyone motivated strictly by self-preservation should consider that losing birds translates to humans losing valuable ecological services. That case is recorded in a book by a group of researchers led by University of Utah biology professor Çağan Şekercioğlu. In fact, the book, titled Why Birds Matter: Avian Ecological Function and Ecosystem Services, ascribes a price tag to a few examples. In one case study, the Clark’s nutcracker performs seed dispersal in Colorado that is crucial to the growth of a species of pine tree, a service that would cost the state $2,400 per bird to duplicate with human labor. In Washington, avian control of a crop pest called the spruce budworm has a value of $3,815 per square mile per year. Meanwhile, globally birds are responsible for dispersing the seeds of up to 92 percent of tree and woody plant species, including 85 species of tree, 182 edible plants including spices, and 153 medicinal plants, the researchers write.

To save birds is to save ourselves. All that’s needed is to understand the ways birds are often built out, and then correct that.

Migratory season and route of the birds
Migratory patterns and routes by season

Five Ways Architecture Impacts Birds


A perfect storm of large expanses of glass, birds’ inability to see them, and their unerring adherence to ancient migratory routes has led to mass slaughter of sparrow-size songbirds such as the American goldfinch, wood thrush, and ruby-throated hummingbird. New York City’s shiny towers and canyons of green space are in the path of one of North America’s four “superhighways” for bird migration, the Atlantic Flyway.

“They need to land and rest,” says Piselli, explaining that birds flock where there’s habitat, like in a tree. “Bird-friendly glass is required on facades up to a height of 75 feet, around tree height,” he adds. (NYC Audubon maintains a helpful library of about 100 samples of such glass.) 


Darker night skies are another safety feature urban architects, developers, and landscapers can gift to birds. The worst building collisions involve nighttime migrants who rely on light from the moon, stars, and sunset as guideposts, but mistakenly gravitate toward streetlamps, uplights, and searchlights like those in New York’s 9/11 “Tribute in Light” art installation. “Urban light pollution causes birds to become confused,” says Piselli. That results in their landing in places they shouldn’t, like in parks between glass-covered towers. 

There’s also evidence that artificial light affects birds’ internal clocks and disrupts the timing of such behaviors as dawn song and mating. A 2010 article titled “Artificial Night Lighting Affects Dawn Song, Extra-Pair Siring Success, and Lay Date in Songbirds” in the scientific journal Current Biology names blue tits, chaffinches, and robins among the species notably affected. “Our findings show light pollution influences the timing of breeding behavior, with unknown consequences for bird populations,” says Bart Kempenaers of the Max Planck Institute for Ornithology in Germany. 


Bird population decline is a clear consequence of being displaced by human development. A study in the journal Annual Review of Environment and Resources found 48 percent of existing bird species are known or thought to be declining largely because their natural homes have been destroyed. 

In the absence of deliberately bird-inclusive urban designs, even species that manage to adapt to inhospitable structures (such as peregrine falcons) risk being designed out as a certain typology evolves. For instance, the chimney swift, a cavity nester that naturally favors hollow trees, now nests in many dormant residential chimneys, as its name suggests. As the vernacular for new houses eliminates the chimney, it’s unclear where they’ll go if developers and planners don’t restore the wild habitats that used to offer such trees.


Buildings’ toll on birds is especially troubling given their historical roles as predictors of safe conditions for humans. Miners literally carried canaries in cages into tunnels as an early warning system for the presence of deadly levels of carbon monoxide. Similarly, before government action was taken in the mid-1980s, birds in Mexico City dropped mid-flight out of the smog-choked sky. In an inverse of the coal mine scenario, several declining species of birds returned to London after the U.K. passed its Clean Air Act in 1956 to counter fog deemed lethal to humans. Multiple studies also show that chemicals emitted by the heavy traffic of urban areas can cause birds to experience reduced egg production and lower body mass.


Even gardening and manicured lawns can create an unexpected imbalance, with a negative impact on birds. Jones, the author of The Birds at My Table, writes that native plantings may still be engineered to feature artificially long-lived bloom times—people pleasers that disrupt the natural diversity of food sources available to birds. A result might be too much access, causing them to overindulge and fail to migrate, working against their own better instincts for survival. 

“Because of the usual human preference for large, colorful flowering displays, species and varieties selected for these places are typically showy. It’s what people want to see,” Jones writes. “And what we appreciate aesthetically, our. . .nectar-feeding visitors enjoy as an unnaturally prolonged supply of their favorite foraging resources.”

Designers and architects often mean well, but there will be times when nature knows best.

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