Contemporary homes and modern office buildings often use insulated and reflective glass to replace walls. These windows may be aesthetically pleasing to humans, but often they are lethal to birds. Unfortunately, many birds cannot distinguish the difference between the real sky and a reflection of the sky in a window.

In the United States alone, it is estimated that each year during migration, millions of birds fly full tilt into windows and are seriously injured or killed.

You can minimize these collisions by breaking up the reflection on the outside of the window with a window screen, flash tape and bird netting.

Life-size, animate "scares" (plastic falcons, owls and balloons) and falcon or owl silhouettes attached to windows with suction cups are not effective deterrents.

Planting trees and installing window awnings to block the sun from hitting the window may eliminate some reflection.

Migration isn't the only time homeowners have trouble with bird-window collisions. Birds may hit your windows during breeding season, and in the winter too.

During breeding season, male cardinals, woodpeckers and mockingbirds may "fight" their own reflections in windows (and car mirrors). They'll stop banging into the window as the breeding season ends. You can discourage them with screens and other barrier techniques.

Regardless of the season, birds can fly into windows when they're frightened while visiting a feeding station. Either move the feeders a considerable distance away from the window, or immediately adjacent to the window (so birds don't get up to flight speed before hitting the window).