FAQs

After colliding with glass, some birds may fly away or be only temporarily stunned.

Unfortunately in most of these cases, the birds do not survive off-scene of the collision. Flying into glass can cause internal hemorrhages, concussions, or damage to bird’s bills, wings, eyes, or skulls. While they may be able to fly temporarily, birds with even moderate injuries are much more vulnerable to predators and other environmental dangers.

These off-site deaths also likely go unaccounted for, making the real number of bird deaths by collision even higher than already estimated.

Collisions often go unnoticed at both homes and commercial buildings for several reasons. First, many of the birds that hit windows do not die immediately and fly off without leaving a trace. Unfortunately, these birds usually die off-site by either succumbing to injuries or being more vulnerable to predators.

The bodies of birds that die on impact are often quickly disposed of by facilities managers that work early hours or by animal scavengers. Domestic cats, raccoons, birds of prey, gulls, and even squirrels, have been observed revisiting or waiting at windows where collisions frequently occur for an easy meal.

Birds may also fall where they cannot be accessed, whether on rooftops, through grates, in landscaping features, or into dense vegetation that makes them difficult to see.

If you have not seen collisions at your home or business, that does not mean they are not happening.

What is described here is not collision but actually reflection aggression. The bird is viewing the reflection in the glass as a real competitor and attacking the image. The species most likely to do this are those that nest close to houses, such as American Robins, Northern Cardinals, bluebirds, California Towhees, Chipping Sparrows, and Song Sparrows. Both males and females  can engage in this behavior.

The solution is the same as that for collision, as the reflection is the source of the problem. Break up the reflection with glass treatments recommended on this site to solve the issue. If this behavior continues, it is likely that the bird is attacking his reflection in the glass that is not covered by decals, and more total coverage may be necessary.

Unfortunately, hawk silhouette decals do very little to deter birds even from reflection aggression as they are quickly recognized as non-threats. Furthermore, they do not tend to cover the amount of glass necessary to prevent collision. Patterns must cover glass at a spacing of 2” by 2” apart to cover the small spaces that a bird may otherwise think it can fly through (the way they can fly through small gaps in bushes and trees!).

Although blinds and pulled curtains at night can reduce light pollution and the number of birds that are attracted into urban areas, it is not a solution to preventing glass collisions. Sometimes having curtains pulled internally can even worsen the reflective quality of glass and make it more dangerous to birds! Solutions to prevent glass collisions must be placed externally on the glass and either cover the glass entirely (like insect screens) or be spaced 2×2” apart.

No, this is a common misconception. In 2014, Smithsonian researchers estimated that homes and other buildings one to three stories tall accounted for 44 percent of all bird fatalities and high-rise buildings. Skyscrapers can be higher in number of collisions per individual building, but they are limited in numbers, whereas there are millions of residential and < 3 story buildings.

Internal treatments are not recommended in almost every case because they do not resolve the issue of glass reflectivity and can even make reflectivity worse.

If you are treating a standalone glass structure like a railing that may be threatening from both sides, determine if the glass is reflective or just transparent. If it is reflective at all during the day, you will need to treat both sides to prevent collisions.

If the glass you want to treat is very difficult to reach, consider hiring a professional to install your treatment for you. If the only possible action is to treat the inside of the glass, do this test first:

Tape paper or sticky notes to the inside of the glass. Starting in the early morning, look at the treated glass from the outside every 2-3 hours. If you can see your treatment clearly through the glass for most of the day, birds might be able to as well, and you can apply an internal treatment.

Generally it is cheaper to choose DIY options to treat your windows. Tempera paint is cheap and works well, though it must be re-applied. A bar of soap can even be used to draw patterns on the outside of glass as an inexpensive temporary solution!

Start by identifying dangerous windows, including large picture windows, paired windows at right angles to each other, or windows with feeders outside. Go outside and look at your windows from a bird’s point of view. If you see branches or sky reflected in or visible through the glass, that’s what the birds will see, too.

The Material Threat Factor system, developed by the American Bird Conservancy,  is used to determine the effectiveness of bird friendly materials. 

The Threat Factor of a material is based on flying at least 80 individual birds down a testing tunnel and recording whether they fly toward the control (regular piece of glass) or to the patterned test glass (with a soft net in front for safety). For example, suppose 80 birds flew toward the panes, with 20 flying toward the test pattern and 60 toward the control. Twenty five percent of the birds flew toward the test pattern and it would therefore have a Threat Factor of 25. 

The ABC defines bird-friendly material conservatively, as having a threat factor of less than 30, corresponding to a reduction of collisions of at least 50 percent. The lower the Threat Factor, the more effective the test pattern will be at reducing collisions. Learn more.

Vinyl decals do eventually need to be replaced, but when this becomes necessary depends on the product, conditions of the installation, and weather conditions around your household. If you do not notice the decals peeling or otherwise fading/degrading, then there is no reason to replace them.

Most bird-friendly products are long-lasting (up to 15 years), with new products on the market like Feather Friendly Evolution™designed to be effective for over 20 years.

Yes! Bird-friendly decals have been designed to withstand regular window washings for many years. After the installation of decals, allow the adhesive to set for 30 days before cleaning. You can then clean with a soft cloth, paper towels, or rubber squeegee, along with typical cleaning products for glass, including soap and water and glass cleaners like Windex. However, it is not recommended to use pressure washers or abrasive cleaners on the decals.

The spacing of bird-friendly products is meant to deter birds used to flying into small gaps in vegetation for shelter. Small species like hummingbirds and kinglets perceive any space larger than 2 inches as large enough for them to fly through which is why the maximum spacing recommendation for most products is 2×2”.

Unlike the 2-dimensional solution of vinyl film, however, hanging paracords take up 3-dimensional space and their shadow and movement also disturb reflection which is why their maximum spacing recommendation is 4”.

Any glass that is transparent or reflective poses a threat to birds. Here are a few examples of glass that would not pose a threat to birds:

1. Glass covered by external screens or shading systems, including louvers.
2. Stained glass
3. Layered or channeled glass including glass block, channel glass, laminated safety glass, and spandrel glass.
4. Antique glass, also known as “wavy glass.” The distortions and imperfections in this traditionally handblown glass may reduce reflections and make it more visible to birds.
5. Dirty glass. Passive problem-solvers, rejoice! Dirty windows can be more visible to birds.

After colliding with glass, some birds may fly away or be only temporarily stunned or injured. Birds that may not look hurt could be suffering from internal injury.

If you find a stunned bird, follow these instructions and try to get the bird to a local wildlife rehabilitator as quickly as possible. If you find a stunned bird that is in a dangerous location (i.e. in the street, on an exposed sidewalk) and you do not have the ability to safely capture the bird (or there is no nearby wildlife rehabilitation center), you can try to gently re-locate the bird under nearby vegetation to better its chances of recovering and avoiding predation.

If possible to do without disturbing the bird, take photos and submit the collision to your local collision monitoring group and the Global Bird Collision Mapper.

Anywhere where there is transparent or reflective glass near vegetation that birds are using, you can assume that collisions are occurring. To start learning where collisions are happening at your home and near you:

• Listen for thud sounds: Birds make an unmistakable ‘thud’ sound when they fly into windows.
• Look for marks in glass: When birds strike windows, oil on their feathers can leave marks and impressions on glass, sometimes in remarkably accurate silhouettes.
• Search for Injured/Dead Birds: Regularly inspect the ground and vegetation under / around your windows to check for injured or deceased birds. Many birds are small and have well-camouflaged feathers which can make them difficult to see on the ground unless you are closely looking.
• Utilize GPS Data: Check GPS data sites like Flap Mapper, dBird, and Global Bird Collision Mapper to check for reported collisions near you.

It is important to report collisions wherever possible to contribute to greater understanding of this issue. There is a section of our new website that may guide you to local organizations that would take these submissions. Otherwise, collisions can be recorded to dbird or the Global Bird Collision Mapper.

Yes! I would recommend rallying neighbors in your apartment complex to submit a request to your building manager/owner to act against this issue as a first step. There are many options to help protect birds without permanently altering windows, including tempera paint, paint markers, and paracord.

In addition to making your windows visible to birds, you can also turn lights out at your residence during both spring migration (March-June) and fall migration (August-November).

It is important to approach people with openness and understanding. Assume people are not taking action on this because of a lack of knowledge, not a lack of caring. Be as prepared as possible with local statistics (building-specific is ideal) and community testimony. “Know your ask”– what specifically do you want this person to change or take action on? What are the benefits?

Unfortunately, we will come across businesses that are unwilling to make these changes. However, even when we hit walls, our efforts are not wasted! The best way to move forward is to not allow setbacks to compromise our own motivation and forward-motion in generating widespread change! 

Involve others, continue to deliver consequences for harmful inaction (i.e. if you do not change this, my community and I will not be spending our money with you). Social and financial pressure can have a strong impact.

Not at all! Buildings can be made bird-friendly without sacrificing natural light or views. The visual interruption of the small patterns on bird-friendly films and glass can be extremely minimal, as shown in this helpful glass visualizer developed by Guardian Glass.

No, in fact, we believe the guidelines for bird-friendly design practices will push the limits of creative design as we know it by generating new innovations, incorporating different perspectives, and thinking “outside the box”!

Not necessarily. Bird-friendly design practices are simply another factor when selecting a design intention for a facade and outlining a construction budget.

Although there can be a slight premium for acid-etch or ceramic-frit patterned glass, especially for a custom pattern, this cost is often offset by the gains the glass adds to the overall thermal performance of the building. The lifespan cost of products should be considered also; bird-friendly glass may be more expensive upfront but adhesive solutions have a shorter lifespan (although still up to 10-15 years!) and therefore will require maintenance costs.

It is ideal for all glass in a building to be made visible to birds, but certain architectural aspects are and glass placements on a building are known to pose a higher risk of collision and can be prioritized for bird-friendly treatment. A window replacement or facade renovation project can also be an opportune moment to incorporate bird-friendly features. 

In general, protecting birds is a win for any company’s sustainability efforts and can be publicized as such in any press about the new construction.

Not only can bird-friendly design contribute to a building’s architectural statement, but it can also support daylighting strategies for a building. Many bird-friendly glass products can be used to increase a building’s energy efficiency by reducing solar heat gain and glare, positively impacting heating and cooling loads.