When birds and buildings collide

One billion birds collide into windows each year while trying to reach reflected vegetation. (Guilhem Vellut/Flickr, Creative Commons

One billion birds collide into windows each year while trying to reach reflected vegetation. (Guilhem Vellut/Flickr, Creative Commons

With about 7.4 billion Americans pointing their binoculars to the skies, birdwatching is one of the country’s most popular outdoor pursuits. As an indoor pursuit, however, birding can be dangerous—for the birds, that is. A Smithsonian-led study estimated that one billion birds collide into windows each year while trying to reach reflected vegetation, and 50% of those collisions happen near feeders.

Songbirds typically flit around your backyard at speeds of 8-15 miles per hour. When charismatic cardinals and goldfinches strike buildings head-on at top speed, however, they can suffer brain hemorrhages that ultimately kill them.

The Rock Pigeon, a familiar city resident, is more adept at avoiding buildings. Researchers at Harvard have discovered flight behaviors that allow them to shimmy through tight spaces. The Rock Pigeon, which has colonized buildings near North Garage and several more on Horsebarn Hill, has expanded its range across North America since the continent’s first European settlers introduced them as messengers. Apart from the Peregrine Falcon, which at top speed of 200 miles per hour is the world’s fastest animal, few native North American species have learned to dodge windows and inhabit urban environments.

Most native birds have not kept up with human development in America over the past 400 years, so centuries-old migration routes consequently wind through cities. With fall approaching, we are smack dab in the middle of songbird migration—September is when warblers, vireos and thrushes flood through our woodlands and gardens en route to the tropics. They migrate by night to avoid aerial predators like hawks, which take to the skies by day. Although not all migratory birds come to feeders, they can be lured close to buildings at night by bright, artificial light.

The September 11th memorial in New York City, for instance, is illuminated on the tragic day’s anniversary, but migratory birds passing overhead each year confuse the beams for daylight and fly dangerously close to skyscrapers. New York City Audubon volunteers monitor the tribute and museum officials shut the lights off periodically to let birds continue their journey. 

Unfortunately, several bird-building collisions occur on the University of Connecticut Storrs campus each year, mostly during migration. Many of these casualties come to UConn vertebrate collections, where ecology and evolutionary biology professor Susan Hochgraf trains students to preserve them for future study. If you find a dead bird anywhere on campus, put it in a plastic bag in your freezer and send her an email (susan.hochgraf@uconn.edu).

With the addition of a new window-laden engineering building between the Chemistry building and the School of Pharmacy, and another highly reflective building on Discovery Drive, birds have a few more obstacles to overcome. Fortunately, there is a solution.

The American Bird Conservancy (ABC) has developed “Bird Tape” as a visual cue for birds encountering windows. These quarter-inch-wide tape strips, when placed two inches apart, can distort a window reflection enough for a bird to realize there are no trees in your living room.  Feeders are generally beneficial to birds in winter when resources are scarce, but careful placement is key, according to the ABC.


Nicholas Russo is a campus correspondent for The Daily Campus. He can be reached via email at nicholas.russo@uconn.edu.