Clear & Present Danger: Sheet Glass Windows Take a Heavy Toll on Birds

Written By Daniel Klem Jr.

Feather dust impact impression from a bird strike.

Imagine an invisible and immovable barrier placed along a busy thoroughfare, indiscriminately killing millions each year. Old and young, healthy and frail, all going about their lives, all equally at risk and none aware of the danger.

Sadly, many birds find themselves in exactly this situation. Year after year, vast numbers across multiple species die colliding with such an obstacle. The culprit? Glass.

Though useful and attractive in homes and buildings, sheet glass windows pose a serious threat to birds everywhere. Clear windows – such as those found in corridors and atria, and in high-rises and homes – act as mirrors, presenting birds with realistic reflections of habitat and sky. They see only open landscapes, and fail to recognize the danger until it’s too late. Many fly into panes of glass trying to reach the vistas beyond, injuring themselves or losing their lives as a result. You may have heard the sickening thud of a bird strike yourself, or found one dead on the ground beneath a window, another victim of this tragic – and largely unreported – circumstance.

During migration, when larger numbers of birds are on the move, window strikes garner some attention as they typically involve dramatic, single-kill events of hundreds of birds at a time (usually from collisions into city high-rises). However, window strikes are not a seasonal phenomenon, and are not restricted to buildings of a certain height. Many scientific studies have revealed that birds hit windows year-round, at any time of day, during all kinds of weather, and against multiple types of structures. In fact, the vast majority of strikes involve homes and low- to medium-rise buildings (less than 11 stories tall). High-rises are responsible for less than 1% – yet bird collisions with them receive the most attention.

These strikes exact a heavy toll. In the United States alone, between 365 million and 1 billion birds die in window collisions each year. Consider this: the lower limit represents 1 million fatal bird strikes every day. We all immediately understand the impact of environmental disasters like oil spills, but it would take multiple hundreds of Exxon Valdez or Deepwater Horizon accidents to match even the low end of annual casualties wrought by our seemingly innocuous windows. And even though this calamity is well-documented, few people are talking about it or taking action to address it.

The good news is that this is a problem we can do something about. It requires a variety of solutions on multiple scales, but every one of us can play a part. For new construction and remodeling projects, traditional windows can be replaced with bird-safe glass. This is available in two main varieties, and is offered by many manufacturers and fabricators. The first is etched with artistic patterns visible to both birds and people; the second features ultraviolet patterns that are invisible to us but glow like warning signals to the birds – an elegant solution as it protects birds while still offering us an unobstructed view. Guardian Glass in the United States and Walker Glass in Canada have entire brands dedicated to bird-safe glass. Ask your architect or look into them yourself and request the change.

There are many things you can do at home as well. Outdoor window screens can protect birds by preventing or softening impact against the glass. In addition, placing feeders within 3 feet of your house or more than 30 feet away can save birds from an unfortunate fate. At the close end, birds can’t build up enough momentum to harm themselves if they brush up against your windows; at the far end, birds have time to react to and avoid your windows – as long as they can see them.

Several companies offer inexpensive products to make windows more visible to birds. Plain or patterned bird tape and easy-cling decals break up reflections; some also contain components that reflect ultraviolet light, to which birds’ eyes are highly sensitive. These products can be easily applied to the outside of your windows, and are removable should you need to replace them. The Wetlands Institute uses tape on its windows where reflections are problematic, and has seen a dramatic decrease in strikes. Hanging lengths of thin rope or paracord in front of your windows also keeps birds from hitting them, breaking up reflections as it moves in the breeze. For the artistically minded, you can increase the visibility of your windows by creating patterns on the outside of the glass with tempera paint. These solutions can all help birds avoid fatal collisions. Whichever method you choose, though, it is important to space elements 4 inches apart in vertical columns and 2 inches apart in horizontal rows. This pattern has been shown to be the most effective at helping prevent window strikes.

By taking a few simple steps to make our homes safer for birds, by speaking up on their behalf and insisting that architects, developers, and contractors incorporate bird-safe glass in their creations, we can turn this terrible tragedy into an uplifting environmental success story. The best time to save species is when they are still abundant, before they become a conservation concern – and window strikes affect both the abundant and the threatened. We have the power and the means to build a better, kinder world for these marvelous creatures. All we need now is the will.

How You Can Help

Below are some simple steps you can take to make a difference in the lives of birds.

  • Apply bird-friendly tape or decals* to the outside of your windows, as follows:
    - Vertical columns spaced 4 inches apart
    - Horizontal rows spaced 2 inches apart

  • Hang lengths of paracord† outside your windows, in vertical columns spaced 4 inches apart.

  • Leave outdoor window screens in place all year.

  • Place bird feeders within 3 feet of your windows, or greater than 30 feet away.

  • Be a voice for birds: contact lawmakers, developers, and architects and urge them to use bird-friendly glass for new construction and remodeling.

For more information or helpful suggestions, please see the new book “Solid Air, Invisible Killer: Saving Billions of Birds from Windows” by Daniel Klem.

*Available at The Wetlands Institute, or online through:

†Available online through:

Daniel Klem Jr.
Previous

We’ll Cross That Bridge: County Commission Chief’s Overview of the Spans That Connect Us
Next

Here’s the Dish: Executive Chef Jim Kurtz of ICONA Windrift