Introduction
Why <strong>Bird</strong>s MatterFor many people, birds and nature have intrinsicworth. <strong>Bird</strong>s have been important to humansthroughout history, often used to symbolize culturalvalues such as peace, freedom, and fidelity.In addition to the pleasure they can bring to people,we depend on them for critical ecological functions.<strong>Bird</strong>s consume vast quantities of insects, and controlrodent populations, reducing damage to crops andforests, and helping limit the transmission of diseasessuch as West Nile virus, dengue fever, and malaria.<strong>Bird</strong>s play a vital role in regenerating habitats by pollinatingplants and dispersing seeds.<strong>Bird</strong>s are also a vast economic resource. Accordingto the U.S. Fish and Wildlife Service, bird watching isone of the fastest growing leisure activities in NorthAmerica, and a multi-billion-dollar industry.The Legal LandscapeAt the start of the 20th Century, following theextinction of the Passenger Pigeon and the nearextinction of other bird species due to unregulatedhunting, laws were passed to protect bird populations.Among them was the Migratory <strong>Bird</strong> TreatyAct (MBTA), which made it illegal to kill a migratorybird without a permit. The scope of this law, whichis still in effect today, extends beyond hunting, suchthat anyone causing the death of a migratory bird,even if unintentionally, can be prosecuted if thatdeath is deemed to have been foreseeable. Thismay include bird deaths due to collisions with glass,though there have yet to be any prosecutions in theUnited States for such incidents. Violations of theMBTA can result in fines of up to $500 per incidentand up to six months in prison.The Bald and Golden Eagle Protection Act (originallythe Bald Eagle Protection Act of 1940), the EndangeredSpecies Act (1973), and the Wild <strong>Bird</strong> ConservationAct (1992) provide further protections forbirds that may be relevant to building collisions.Recent legislation, primarily at the city and statelevel, has addressed the problem of mortality frombuilding collisions and light pollution. Cook County,Illinois, San Francisco, California, Toronto, Canada,and the State of Minnesota have all passed laws orordinances aimed at reducing bird kills, while otherauthorities have pushed for voluntary measures.The International Dark Skies Foundation, an environmentalorganization whose mission is “to preserveand protect the nighttime environment” now activelysupports legislation designed to protect birdsby curbing light emissions.Glass: The Invisible ThreatGlass can be invisible to both birds and humans.Humans learn to see glass through a combinationof experience (how many of us at some time in ourlives have walked into a glass door or seen somebodydo so?), visual cues, and expectation, but birdsare unable to use these signals. Most birds’ first encounterwith glass is fatal when they collide with itat full speed.No one knows exactly how many birds are killed byglass – the problem exists on too great a scale, bothin terms of geography and quantity – but estimatesrange from 100 million to one billion birds each yearin the United States. Despite the enormity of theThe hummingbird habit of ‘trap-lining’ – flying quickly from one feedingspot to another – causes collisions when flowers or feeders are reflected inglass. Photo: Terry Sohlproblem, however, currently available solutions canreduce bird mortality while retaining the advantagesthat glass offers as a construction material, withoutsacrificing architectural standards.Lighting: Exacerbating the ThreatThe problem of bird collisions with glass is greatlyexacerbated by artificial light. Light escaping frombuilding interiors or from exterior fixtures can attractbirds, particularly during migration on foggy nightsor when the cloud base is low. Strong beams of lightcan cause birds to circle in confusion and collidewith structures, each other, or even the ground.Others may simply land in lighted areas and mustthen navigate an urban environment rife with otherdangers, including more glass.<strong>Bird</strong>s and the Built EnvironmentHumans first began using glass in Egypt, around3500 BCE. Glass blowing, invented by the Romansin the early First Century CE, greatly increased theways glass could be used, including the first use ofcrude glass windows. Although the Crystal Palace inLondon, England, erected in 1851, is considered by(Opposite) The White-throated Sparrow is the most frequent victim ofcollisions reported by urban monitoring programs. Photo: Robert Royse<strong>Bird</strong>-<strong>Friendly</strong> <strong>Building</strong> <strong>Design</strong>7