During the fall bird migration season that ended a few weeks ago, hundreds of stunned and dead birds were found in front of many lakefront Northwestern University buildings.
Each year from mid-March through early June and again in late August through late October it is estimated that close to a million of the approximately 8 million birds that migrate along the Mississippi Flyway are killed in the Chicago area by flying into windows.
On the NU campus most bird deaths occur at night or in the very early morning. Migrating birds typically fly at night and then drop down in the early morning to forage for food to sustain them on their next flight. Birds use the night sky to orient themselves. Lights on or in buildings disorient and attract them. At dawn birds mistake the reflections of sky, clouds and trees on window glass for open air and fly into the windows.
In 2003-04 members of the Evanston North Shore Bird Club studied bird deaths on the NU campus and confirmed that the largest number of stunned and dead birds was found at these buildings: the Frances Searle Building, the Mudd Science and Engineering Library, Cook Hall and Norris Center. The mirrored glass of Searle’s windows is the most difficult for birds to perceive as a solid plane.
Early every morning, volunteers like Evanston artist Peggy Macnamara scout the areas on the NU campus where birds are most often found, collect the dead birds and deliver them to the Preparation Lab at the Field Museum. In downtown Chicago, members of a group known as the Chicago Bird Collision Monitors (see Sidebar) conduct similar pick-ups.
At the Field Museum lab, volunteers label the birds with the date and location of death, the name of the finder, their sex, and the amount of fat they contain. The skeleton is removed from the skin and the birds filled with cotton to preserve them for future study by researchers and educators. The efforts of volunteers thus contribute to some potentially positive scientific benefits from the deaths of so many birds.
The general public is unaware of the dead birds because most are removed soon after they die by janitorial crews, homeowners or animal scavengers such as squirrels, rats, raccoons, possums, dogs and cats.
Birds have been flying into windows in large numbers since “picture” windows became common in the 1950s and began to be incorporated into buildings ranging from suburban ranch houses to urban high rises.
Window and glass manufacturers are now developing new types of glass that birds can read as solid surfaces, lessening the chances that birds will mistake the glass for open space. Ornilux Bird Protection Glass, 4BIRD protection glass and Ferro enamels used for external patterns on glass are among the products available to architects. Some glass incorporates a UV-reflective coating that is transparent but makes the glass look like a solid to birds.
Building designs can reduce bird deaths as well. The addition to the Adler Planetarium has sloped glass windows that birds can see. When the new Soldier Field was built, there was concern that birds would be attracted to it, but the sloping glass on the lower portion of the structure is visible to the birds. Bird monitors have found no dead birds there.
Spertus Museum of Judaica on Michigan Avenue in Chicago, built in 2007, presents a 10-story faceted window wall with lake views that birds read well. The glass in the windows at Spertus has a 40 percent ceramic “frit” pattern in it made up of .125 inch white dots. Glass with “fritting” (ceramic lines or dots on glass) reads to the birds as a solid but still permits people inside to see out. In general, window designs in which there are patterns or in which the window expanses are broken up into sections are more bird-safe.
Bird-safe design practices, such as the use of window blinds and exterior screens, often have the added benefit of increasing the energy efficiency of the building, reducing heat gain and thus cooling costs. The Levy Center in Evanston is a good example. The “Lights Out” campaigns in many cities reduce electrical bills for owners and improve the night sky for stargazers. A recent incentive for architects, designers, building owners and developers to use bird-safe designs in their buildings is that the U.S. Green Building Council (USGBC) now gives credits toward LEED (Leadership in Energy and Environmental Design) certification for such designs.
Retrofitting existing buildings with bird-safe design features is often a challenge.
No one wants to give up a good view. Websites listed below include suggestions for retrofit solutions. NU has tried decals, but they have not been successful in reducing bird deaths. Designing bird-safe new buildings is easier than retrofitting existing ones, since it may be a matter of simply improving technology of the window glass itself.
Bird deaths from window collisions have become such a concern that many cities are legislating or offering guidelines to address the issue. These guidelines in particular encourage Lights Out programs in which building lights are at least dimmed. McCormick Place has achieved an 80 percent reduction in bird fatalities since lights have been turned out there.
The cities of Chicago (www.cityofchicago.org/city/en/depts/doe/supp_info/lights_out_chicago.html), New York (Project Safe Flight: www.nycaudubon.org/projects/safeflight), and Toronto (www.toronto.ca/lightsout/index.html) have been dealing with this issue by encouraging high-rise building owners to dim their lights during migration periods. In October, San Francisco updated its “Bird-Safe Building Standards” and the Federal Bird-Safe Buildings Act of 2011 (HR 1643) was introduced. The Chicago Park District and Cook County have also adopted bird-safe design practices.And at NU, new lakefront buildings present both a challenge and an opportunity to incorporate the latest glass technologies and design guidelines for reducing bird deaths. The architects for the new Bienen School of Music building, Goettsch Partners, are using a less reflective glass. As more architects design with birds in mind, the lakefront, one of the most bird-friendly habitats, will no longer be one of the most dangerous.
For the Birds, ReallyChicago Bird Collision Monitors maintains a hotline throughout the year for people who find injured birds (773-988-1867). The group’s website, www.birdmonitors.net, also lists suggestions to help building managers, architects, landscapers and homeowners reduce the risk of bird strikes. The group was formed in 2003 to encourage Chicago’s Lights Out campaign.
• www.flap.org (Fatal Light Awareness Program) is an excellent website about the City of Toronto’s bird safety programs. It includes a chart listing human causes of bird deaths, with building collisions at the top (killing up to 1 billion birds a year). Loss of habitat due to new development is listed fifth, although some studies of bird death put it first. There is also an excellent list of the “Top Ten Ways to Make Glass Less of a Hazard for Birds.”
• http://mn.audubon.org/birds-science-education/project-birdsafe/birssafe-buildings. Developed by Audubon Minnesota, this website has some very clear bird-safe building guidelines.
• http://www.abcbirds.org/newsandreports/release/111031.html. The American Bird Conservancy’s website includes an article on the new LEED credits available for buildings with bird-friendly designs.
• http://www.ornilux.com. This website of a glass manufacturer is a look at how a business is addressing a need.
• http://www.windowcollisions.info/public/nyc-birdsafeguidelines-2007.pdf. Hillary Brown, a New York architect, co-authored the booklet “Bird Safe Building Guidelines.” It is comprehensive, with a focus on what architects can do.