Birds face innumerable threats in our human built environment and our glass surfaces are one of the biggest.

During daylight hours, birds collide with reflective surfaces when they stop to feed or rest, when avoiding a predator or flying from tree to tree. Shiny glass exteriors, internal plants near windows, glass corners, and greenery close to buildings can all be deadly as birds are unable to distinguish reflection from open flyway. For every collision victim found, three more typically go unseen, flying out of sight before falling or being carried away by predators.

Window collisions are one of the leading direct human causes of bird mortality. A 2014 study by the US Fish and Wildlife Service and the Smithsonian Institution estimated that between 365 and 988 million birds are killed annually by building collisions in the U.S.

To determine the extent of the problem in our area and if there are any buildings that present a serious problem for birds we have developed this Bird Friendly Buildings section of our website.

Making your Windows Safer for Birds

Photo: Ianmcmat./Imgur

Photo: Ianmcmat./Imgur

Windows in our homes kill hundreds of millions of birds every year. One million a day is the low estimate!

Most of us have heard the "thud" of a bird crashing into one of our windows. Most collisions are not as obvious as the one above of a Yellow-shafted Sapsucker.

SAD FACTS:

  • Up to 50% of bird-window collisions leave no evidence at all.

  • Many of the birds that fly away, likely die later of their injuries.

  • Birds most often suffer concussions and internal injuries which can take days to kill them. They do not break their necks.

  • If a collision kills a parent bird, the young will most likely also die.

  • Window collisions kill both the fit and unfit, risking weakening the gene pool.

  • This is all preventable if people took action at their own homes.SAD FACTS:

  • Up to 50% of bird-window collisions leave no evidence at all.

  • Many of the birds that fly away, likely die later of their injuries.

  • Birds most often suffer concussions and internal injuries which can take days to kill them. They do not break their necks.

  • If a collision kills a parent bird, the young will most likely also die.

  • Window collisions kill both the fit and unfit, risking weakening the gene pool.

  • This is all preventable if people took action at their own homes.

Learn more here.

Tracking Bird-Window Collisions

Yale University and the Yale Peabody Museum of Natural History have created an iNaturalist project to document bird-window collisions in the city of New Haven, CT, the greater New Haven area, and on Yale University's campus (including on West Campus). Members of the Yale and New Haven communities, as well as visitors, are encouraged to document the bird window strikes that they encounter. The purpose of this project is to help quantify and gather data about bird mortality due to window collision in the city, to identify buildings that are killing birds frequently, and to use this data to propose and advocate for mitigation action to prevent future deaths.

One of the world’s most popular nature apps, iNaturalist helps you identify the plants and animals around you. Get connected with a community of over a million scientists and naturalists who can help you learn more about nature! What’s more, by recording and sharing your observations, you’ll create research quality data for scientists working to better understand and protect nature. iNaturalist is a joint initiative by the California Academy of Sciences and the National Geographic Society.

Get Started

  • Install the iNaturalist mobile apps so you can always observe, even without cell reception or wifi.