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Birds Colliding With Windows

It is estimated that over 100 million birds die in the United States each year as the result of collisions with windows. Research has determined that birds hit every size window: at any height (from a one-story house to high-rise building), anytime, day or night. Window strikes can be deadly for both large and small bird species.

Many of the deaths occur when migrating birds fly into illuminated, high-rise buildings. Twice annually, migrating birds travel to and from their wintering and breeding grounds, a distance anywhere from a few hundred miles to a few thousand miles, depending on the species. For many migrants, these long-distance flights take place at night and, because they are attracted to light, thousands die or are injured when they strike illuminated buildings, especially on foggy or rainy nights.

In residential areas and office parks, windows often reflect nearby trees, shrubs, or sky. Birds do not understand the concept of reflection. When they attempt to fly into the landscape they see, they strike the barrier they can't see - the glass. A bird in a hurry can fly into a window with enough speed to be killed or, if it is lucky, stunned. Predators, especially domestic cats, often take birds that are not killed on impact.

HELPING INJURED BIRDS

When a bird hits a window it can be stunned and temporarily incapacitated due to swelling in the brain. If there is a concern about cats or other predators, the bird can be placed in an enclosed box or under a colander to keep it safe. The bird should be handled as little as possible and no attempt should be made to give it food or water. After two or three hours, as the swelling subsides and the bird becomes more active, it should be released.

If, after three hours, there is no change in the bird's behavior, it is likely that there is internal bleeding and little can be done to save it. Place the bird out of sight and let it die a peaceful death..

PREVENTING WINDOW COLLISIONS

Observation

Window strikes frequently follow a pattern. Dead or injured birds may repeatedly be found beneath the same window and the collisions may occur at certain times of day. To determine what is being reflected in the outside of the window, place yourself directly in front of the glass to see what the birds are seeing. Repeat this at different times of the day to view the window's reflection under different light conditions.

Observe feeders and birdbaths to determine if the birds are colliding with windows as they fly from those locations.

Cover the window with a non-reflective material

There is a commercially available film for window exteriors which claims to reduce the reflectivity of windows without affecting the light entering the room.

Cover the window with an impact-absorbing barrier

Windows can be covered with a screen that is attached to the window using hooks or suction cups. This not only reduces the reflection, it prevents injury by cushioning the bird if it inadvertently flies toward the window. It also prevents territorial birds from attacking their reflection in the glass.

Break up the reflection

It is the reflection that fools the birds, so you need to signal the birds that this is not a safe flying zone.

• Window decals in the shape of hawks are sold to reduce window strikes, but the hawk shape is unimportant (it doesn't fool the birds). Any decals or stickers that are at least 6 inches in diameter can be used. Be sure to place several on the outside of the window, one foot apart, both horizontally and vertically.


• There are now decals that contain a component that brilliantly reflects ultraviolet sunlight, when placed on the outside of the window. This ultraviolet light is invisible to humans, but glows brilliantly for songbirds. The decals, shaped like maple leaves or butterflies, are about 4 by 4 inches.


• Another product uses the motion of brightly colored poultry feathers to warn birds away from glass. It is believed that birds have an aversion to loose, fluttering feathers because they associate them with the attack of a predator. The feathers hang from a five-foot length of monofilament line that attaches to the outside of the window with suction cups.

Mass Audubon cannot make recommendations on products or services, but websites for the products listed above can be found under Product Resources in the Miscellaneous section of the Living with Wildlife Manual.

Other techniques include placing screens on the outside of the windows or hanging several, mylar party streamers or balloons on the outside of the windows.

Relocate bird feeders

Spend time observing the birds at your feeder. If you determine that the birds are flying from a feeder into a window, most researchers agree that the feeder should be moved closer to the window. Birds, flying from a feeder that's only 2 or 3 feet away from the glass, rarely get up enough speed to kill themselves.

Predators in pursuit

A bird being pursued by an avian predator will sometimes fly into a window and there is little that can be done to prevent these collisions. Sharp-shinned Hawks and Cooper's Hawks prey on small birds and have learned to hunt in yards with bird feeders. Songbirds are attracted to bird feeders because our handouts provide an easy source of food and hawks are attracted to an area for the very same reason.

Birds and the Law

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