by Chicago’s 82-story Aqua Tower seems to be blowing with the wind. Its unusual curved facade makes it one of the most unique features of the Chicago skyline, different from the many rectangular glass towers that surround it.
When designing it, architect Jeanne Gang thought not only of how people would see it, dancing against the sky, but also how it would look to the birds flying past. The irregularity of the building’s facade allows birds to see it more clearly and avoid fatal collisions. “It’s designed to work for both people and birds,” she said.
Up to 1 billion birds in the US die in construction collisions each year. And Chicago, which sits along the Mississippi Flyway, one of the four main north-south migration routes, is among the most dangerous places for birds. This year, at least 1,000 birds died in one day from a collision with a single glass-enclosed building. In New York, located along the Atlantic Flyway, hundreds of species cross the skyline and thousands die each year.
As awareness grows of the dangers of glass towers and bright lights, architects are beginning to reimagine city skylines to design buildings that are both aesthetically bold and bird-safe.
Some are experimenting with new types of patterned or coated glass that birds can see. Others are rethinking glass towers entirely, experimenting with exteriors that use wooden, concrete or steel rods. Blurring lines between inside and outside, some architects are creating green roofs and facades, inviting birds to nest inside the building.
“Many people think of bird-friendly design as another limitation on buildings, but another requirement,” said Dan Piselli, director of sustainability at New York-based architecture firm FXCollaborative. “But there are so many design-forward buildings that perfectly demonstrate that this doesn’t have to limit your design or your freedom.”
How modern buildings endanger birds
For Deborah Laurel, principal of the firm Prendergast Laurel Architects, the realization came a few decades ago. She was celebrating her firm’s renovation of the Staten Island Children’s Museum when the museum’s director told her that some birds were crashing into the new addition. “I was horrified,” she said.
She embarked on research to learn more about bird collisions. After several years of investigation, she found that there were few practical tips available for architects, and teamed up with the conservation group NYC Audubon, to develop a bird-safe building guide.
The problem, she found, was that technological and architectural advances over the past half century had transformed New York City – and most US skylines and suburbs – in some ways into death traps for birds. .
Before the 1960s, much of the large sheet glass used in buildings was made through a complex and expensive process of casting and polishing. The glass often contained bubbles or other imperfections that obscured its clarity.
Then, in the 1960s, float glass – made using a new technique that created clear, uniform sheets – became widely available. “This new glass is very perfect – perfectly flat, perfectly smooth and it’s also more reflective,” explained Laurel. In the years that followed, builders added more and more double pane glass, which was intended to help insulate buildings and conserve energy but had the added effect of making the glass even more reflective. “Both of these steps in technology have had a profound impact on birds.”
At certain times of the day, tall glass towers almost blend into the sky. At other times, windows look so clear that they are imperceptible to birds, which may try to fly through. During the day, trees and greenery reflected on shiny building facades can attract birds, but at night, brightly lit buildings can confuse and mislead them.
Unfortunately for the birds, in the 1970s, the lustrous glass look became a popular design aesthetic, and the look has stuck ever since. “It started with the good intention of wanting light-filled spaces, to help people feel a sense of openness,” Piselli said. “But the subject has these multifaceted consequences.”
The changes that could save bird life
About a decade ago, Piselli’s firm worked on a half-billion dollar renovation of the Jacob K Javits Convention Center in New York, a glass-encased space frame structure that was killing 4,000-5,000 birds a year. “The building was this black death star in the urban landscape,” Piselli said.
To make it more bird-friendly, FXCollaborative (then known as FXFowle) reduced the size of the glass and replaced the rest with fritted glass, which has a ceramic pattern baked into it. Small textured dots on the glass are barely visible to humans – but birds can see them. The fritted glass can also help reduce the heat of the sun, keep the building cooler and lower air conditioning costs. “This has become the poster child for bird-friendly design over the past decade,” Piselli said.
The renovation also included a green roof, monitored by the NYC Audubon. The roof now serves as a sanctuary for several species of birds, including a colony of herring gulls. Living roofs have been popular ever since in New York and other large cities, in an inversion of the decades-old practice of reinforcing buildings with anti-bird spikes. In the Netherlands, there are nesting boxes and spaces where birds and bats can live in front of the headquarters of the World Wildlife Fund, a futuristic structure that looks like a curved blob of mercury.
The use of fritted glass has also become more popular as a way to save the birds and energy.
Earlier this year, Azadeh Omidfar Sawyer, an assistant professor of building technology at the Carnegie Mellon School of Architecture, developed open-source software to help designers create custom glass patterns that are bird-friendly. Sawyer’s recently published book of 50 patterns includes complex geometric lattices and abstract arrays of lines and blobs. “Any architect can pick up this book and pick a pattern they like, or they can customize it,” she said.
Breeders are also experimenting with UV-printed patterns, which are invisible to humans but visible to most birds. At night, conservationists and architects are encouraging buildings to turn off lights, especially during migration season, when the bright glow of the city skyline can confuse birds.
And architects are integrating more screens or grates that provide shade as well as visibility for birds. The 52-floor building of the New York Times, for example, uses fritted glass with ceramic rods. The spacing between the rods increases towards the top of the building, giving the impression that the building is dissolving into the sky.
Gang’s work incorporates structures that can also act as blinds for birds, or a perch from which nature can be observed. A theater she designed in Glencoe, Illinois, for example, is surrounded by a walkway made of wooden lattice, where visitors can feel as if they are up in the canopy of trees.
Rejecting the idea of the all-glass building, “where you can’t tell the difference between the habitat and the sky”, Gang aims to do the opposite. “I always tried to make the buildings more visible with light and shadow and geometry, to have a stronger presence,” she said.
Gang is experimenting with placing bird feeders around her own home in an effort to reduce collisions with windows, and she encourages other homeowners to do the same.
“I’ve found that birds slow down and stop feeding rather than trying to fly through the glass,” she said.
While high-rise buildings and massive urban projects get the most attention, low-rise buildings and houses are the cause of bird strike deaths. “The huge challenge is that glass is everywhere.” said Christine Sheppard, who directs the glass collision program at the American Bird Conservancy (ABC). “It’s hard to know what I know and not cry when I look at it.”
Tips to improve your own home include using stained glass or patterned decals that will help birds see the window, she said. ABC has compiled a list of window treatments and materials, ranked by how safe they are for birds.
Whether large or small, the challenge of designing bird-safe buildings can be “liberating,” said Gang, now an avid bird watcher who now carries a pair of binoculars on his morning jogs. . “It gives you another dimension to try to imagine.”
