Can A Bird Break A Window? A Comprehensive Investigation

Birds crashing into windows are an all-too-common occurrence. The collision can seriously injure or even kill the bird. But can a bird’s impact actually break the glass? This detailed guide examines factors influencing whether different species of birds can shatter windows under various conditions.

If you’re short on time, here’s a quick summary: While rare, some large bird species like geese can generate enough force during a collision to fracture certain types of glass.

In this roughly 3000 word article, we’ll analyze bird flight speeds, body mass, beak shape, window materials, thickness, age, angle of impact and more. We’ll also overview Prevention methods, ethical considerations, and mitigation through bird-friendly designs and deterrents.

Bird Flight Speeds and Body Mass

When it comes to birds flying into windows, their flight speeds and body mass play a significant role in determining the likelihood of a collision. Understanding the characteristics of different bird species can provide insights into the potential dangers they pose to windows.

Fastest Flying Birds

Some bird species are known for their incredible speed while in flight. The peregrine falcon, for example, is widely regarded as the fastest bird in the world, reaching speeds of up to 240 miles per hour (386 kilometers per hour) during its hunting dives.

This impressive speed, combined with its relatively small body mass, means that a peregrine falcon could potentially cause significant damage if it were to collide with a window.

Other fast-flying birds include the common swift, which can reach speeds of up to 69 miles per hour (111 kilometers per hour), and the white-throated needletail, which has been recorded flying at speeds of up to 105 miles per hour (169 kilometers per hour).

While these birds may not pose as much of a threat as the peregrine falcon, their speed can still lead to window collisions.

Heaviest Bird Species

On the other end of the spectrum, some bird species have a larger body mass, which can also contribute to the risk of window collisions. The great bustard, for instance, is one of the heaviest flying birds, with males weighing up to 40 pounds (18 kilograms).

Similarly, the mute swan can weigh up to 33 pounds (15 kilograms).

These heavier bird species, although not as fast as the aforementioned falcon or swift, still have the potential to cause damage upon collision due to their size and weight. It’s important to consider the potential impact of these larger birds when assessing the risk of window collisions.

Understanding the flight speeds and body masses of different bird species can help us develop strategies to minimize window collisions. By implementing measures such as bird-friendly window designs or applying decals and window film, we can create safer environments for both birds and humans.

Beak Size, Shape and Sturdiness

When it comes to determining whether a bird can break a window, the size, shape, and sturdiness of its beak play a significant role. Different bird species have evolved with beaks that are adapted to their specific needs, including feeding habits and defense mechanisms.

Let’s take a closer look at how beak characteristics influence a bird’s ability to break through a window.


Raptors, such as hawks and eagles, possess powerful beaks designed for tearing flesh and capturing prey. With their sharp, hooked beaks, these birds have the strength to break through various materials, including glass.

However, it’s important to note that raptors typically avoid colliding with windows due to their excellent eyesight and navigational skills.


Songbirds, such as finches and sparrows, have smaller beaks compared to raptors. While their beaks may not be as powerful, they are still capable of causing damage to windows, especially if they fly into them at high speeds.

The impact force combined with the shape and size of their beaks can lead to broken glass. It’s worth mentioning that songbirds are more commonly involved in window collisions due to their smaller size and faster flight patterns.


Waterfowl, like ducks and geese, have beaks that are primarily used for foraging and filter-feeding. These beaks are not as strong or sharp as those of raptors, making it unlikely for them to break through windows.

However, collisions with windows can still cause injury or disorientation to these birds, leading to potential fatalities. It’s crucial for homeowners near bodies of water to take preventive measures to reduce the risk of window collisions for waterfowl.

It’s important to note that while beak characteristics contribute to a bird’s ability to break a window, other factors such as the speed at which the bird collides with the window and the type of glass also play a significant role.

Understanding these factors can help us develop effective strategies to prevent bird-window collisions and protect both birds and our windows. For more information on bird-window collisions and prevention methods, visit Bird Watcher’s Digest.

Window Glass Types and Properties

When it comes to understanding whether a bird can break a window, it’s important to consider the different types of window glass and their properties. Here, we will delve into the characteristics of annealed, tempered, and laminated glass, as well as factors such as thickness, age, and wear that can affect a window’s durability.

Annealed, Tempered, Laminated

Annealed glass is the most common type of glass used in residential windows. It is the standard glass that is produced by slowly cooling molten glass to relieve internal stress. While annealed glass is relatively strong, it is also more prone to breakage compared to other types of glass.

Tempered glass, on the other hand, undergoes a special heat treatment process that makes it up to four times stronger than annealed glass. When it breaks, it shatters into small, granular pieces instead of sharp shards, reducing the risk of injury.

Tempered glass is often used in areas where safety is a concern, such as shower doors and car windows.

Laminated glass is made by sandwiching a layer of plastic between two layers of glass. This type of glass is known for its safety and security features, as it holds together when shattered. Laminated glass is commonly found in windshields and areas where high impact resistance is required.


The thickness of window glass can also play a role in its vulnerability to breakage. Thicker glass is generally more resistant to impact and less likely to break compared to thinner glass. However, it’s important to note that even thin glass can be reinforced with laminated or tempered properties to enhance its strength.

Age and Wear

Over time, windows may experience wear and tear due to exposure to the elements, changes in temperature, and general aging. This can weaken the glass and make it more susceptible to breakage. It’s important to regularly inspect and maintain windows to ensure their structural integrity.

It’s worth mentioning that while window glass types and properties play a significant role in determining their durability, the force and angle at which a bird collides with a window can also influence whether or not it will break.

Factors such as the speed and size of the bird, as well as the condition of the glass, can all contribute to the likelihood of a window breaking upon impact.

For more information on window glass types and properties, you can visit The Spruce or Hunker.

Angle of Impact and Window Frames

When it comes to birds colliding with windows, the angle of impact plays a crucial role in determining whether the window will break or not. Understanding the different angles at which birds collide with windows can help us devise strategies to minimize such incidents.

Perpendicular vs Glancing Blows

In cases where a bird collides with a window perpendicularly, the chances of the glass breaking are significantly higher. This is because the force of impact is concentrated in a small area, increasing the likelihood of the glass pane shattering.

The sound of such a collision can be quite startling and alarming.

On the other hand, when a bird collides with a window at a glancing angle, the force of impact is spread out over a larger surface area, reducing the chances of the glass breaking. The bird may be momentarily stunned or disoriented, but the window usually remains intact.

However, it is important to note that even glancing blows can result in fatal injuries for birds.

Did you know? According to a study conducted by the American Bird Conservancy, nearly one billion birds die each year in the United States due to collisions with windows. This staggering number highlights the need for effective solutions to mitigate this issue.

Reinforced Frames

Window frames that are reinforced can significantly reduce the risk of a bird breaking a window. Reinforcements can include features such as laminated or tempered glass, which are designed to withstand greater impact forces.

These types of glass are less likely to shatter upon collision, providing a safer environment for both birds and humans.

In addition to reinforced glass, window frames can also be made from materials that are more flexible and less prone to breakage, such as vinyl or fiberglass. These materials offer greater durability and are less likely to crack or break upon impact.

By investing in reinforced window frames, homeowners and businesses can contribute to bird conservation efforts while also ensuring the safety and longevity of their windows.

For more information on bird collisions and window safety, you can visit the American Bird Conservancy’s website:

Documented Window Breakage Incidents


Believe it or not, geese have been known to break windows with their powerful wings. These large birds can reach impressive speeds while flying, and if they collide with a window, the impact can be enough to shatter the glass.

While it may seem like an unlikely occurrence, there have been numerous reports of geese crashing into windows, especially in areas where they congregate in large numbers. In fact, a study conducted by Nature found that window collisions are responsible for a significant number of bird fatalities each year.


Hawks are another bird species that can inadvertently break windows. These birds of prey have incredible speed and agility, allowing them to swoop down on their prey with precision. However, sometimes their hunting maneuvers can go awry, leading to collisions with windows.

The force of a hawk hitting a window at high speed can result in broken glass and potential injuries to the bird. A study published in the Journal of Wildlife Diseases found that window collisions are a common cause of mortality among hawks and other raptors.


Owls, with their silent flight and sharp talons, are often associated with grace and precision in the animal kingdom. However, even these nocturnal hunters can fall victim to window collisions. Owls may be attracted to the reflection of prey or other birds in windows, leading them to fly towards the glass.

The impact can be severe enough to break the window and potentially injure the owl. A study published in the Journal of Avian Biology noted that window collisions are a significant threat to owl populations, especially in urban areas.

It’s important to note that these incidents are not intentional on the part of the birds. They are simply a result of the birds’ natural behaviors and the presence of windows in their environments. To help mitigate window collisions and protect both birds and windows, there are various preventive measures that can be taken, such as applying window decals, installing bird-friendly window treatments, or creating visual barriers outside the windows.

Preventing Collisions and Damage


Preventing bird collisions with windows is an important consideration for both homeowners and architects. There are several effective deterrents that can significantly reduce the risk of birds flying into windows. One popular option is the use of window decals or stickers.

These decals are designed to break up the reflection on the glass, making it more visible to birds. Another effective deterrent is the application of window films, which can be easily applied to the glass surface.

These films are available in various patterns and designs, and they can help to make windows more visible to birds.

Another option for preventing bird collisions is the use of external devices such as bird tape or bird netting. Bird tape is a simple and inexpensive solution, consisting of a reflective tape that can be attached to the outside of windows.

The reflective properties of the tape can help to alert birds to the presence of the window, reducing the risk of collision. Bird netting, on the other hand, is a more comprehensive solution that can be used to cover entire windows or building facades.

This physical barrier prevents birds from coming into direct contact with the glass, reducing the risk of injury.


Architects and building designers can play a crucial role in preventing bird collisions by incorporating bird-friendly designs into their projects. One of the most effective design elements is the use of fritted glass.

Fritted glass is a type of glass that has a pattern of small ceramic dots or lines applied to its surface. These patterns help to break up the reflection on the glass, making it more visible to birds and reducing the risk of collision.

Another design consideration is the use of external shading devices such as awnings or louvers. These devices can help to reduce the amount of glass exposed to direct sunlight, which can minimize reflections and make the windows less attractive to birds.

Additionally, incorporating vegetation or green roofs into the building design can create a more natural habitat for birds, encouraging them to stay away from windows.

It is also important to note that different bird species may have different preferences and behaviors when it comes to window collisions. Architects and designers should consider the local bird population and their habits when designing bird-friendly buildings.

Consulting with experts in bird behavior and conservation can provide valuable insights and guidance in creating safer environments for birds.

For more information on bird-friendly designs and preventing bird collisions, visit the websites of organizations such as the American Bird Conservancy ( and the Bird Collision Avoidance Program (


This comprehensive analysis explored multiple factors influencing if and when a bird can break a window during a collision. While extremely rare, some large birds may muster enough force under certain conditions to fracture glass.

Understanding bird flight kinetics, beak sturdiness, glass properties and effective deterrents is key to reducing window collisions. With thoughtful prevention and bird-friendly designs, we can make our homes and buildings safer for our avian neighbors.

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