Why Are Birds Flying Into My Windows?

Why Are Birds Flying Into My Windows?
caption: Image of bird reflection (left) courtesy of Austin Marshall under CC BY 2.0 and bird imprint image (right) courtesy of Ted under CC BY 2.0

Although the answer could be that a bird sees its reflection in a window like the image shown in the above left panel, flying into a window and leaving an imprint like the image shown in the above right panel may be due to space weather events occurring over the past few days. If a bird keeps flying into your windows, not seeming to know the window is there, check the space weather for the last few days. In this post, we’ll review how birds navigate, effects that may affect bird window strikes, how to check and read space weather, and things you may be able to do to minimize bird strikes to your windows.

Here at Astropictionary, I strive to publish one of the best articles on timely subjects and astronomy/physics related subjects.In this article, I introduce words that are linked to my AstroPictionary Youtube channel that defines and describes these words, as astronomy and astrophysics has one of the largest vocabularies of all the sciences and sometime words are reused with different definitions. In this article, I also cover terms used in space weather; with multiple degrees in physics and engineering and having taught astronomy to over 10,000 higher education students at the largest university in the United States, this article can help you better understand why birds may be crashing into your windows.

How Do Birds Navigate?

Birds use their eyes, brain, and inner ear to locate magnetic fields. Proteins in birds eyes and brains are sensitive to Earth’s magnetic field, and bits of iron in birds’ inner ears allow for birds to align with magnetic fields for navigation. In short, birds have an inner compass that helps them align towards a

caption: Image courtesy of Shyamal under CC BY-SA 3.0

magnetic field for migration like a standard compass; the image above shows how how a compass aligns with Earth magnetic north and south, providing directions to the observer. The AstroPictionary YouTube video below shows how magnetic filings, like bits of iron, align with bar magnets: A positive end of a magnetic filing is attracted to negative end of the bar magnet and a negative end of the same magnetic filing is attracted to the positive end of the same bar magnet. As Earth’s magnetic field is like the bar magnet shown in the video, birds know which way is magnetic north and magnetic south during migration.

The image below shows migration patterns on a map for various different types of birds; the background image is the approximate location of Earth’s magnetic field for the spherical globe with distance labeled with Earth radii numbers. As shown in the image, Earth’s rotation axis is approximately 11o from Earth’s magnetic axis; magnetic south points toward Earth’s geographic north whereas magnetic north points toward Earth’s geographic south.

Caption: Bird migration pattern image courtesy of L. Shymal under Public Domain and Earth magnetic field image courtesy of Drdan14 under CC BY-SA 3.0

Birds align with one of the magnetic field lines to route during long migration patterns. Birds seem to know to stop migration when the dip angle1 between Earth’s magnetic field and the Earth’s surface reaches a desired value; after long migrations, birds return within a few meters of the nesting sites.

Bird Strike Patterns

Bird strikes to windows occur more often in densely populated areas like cities compared to rural areas as cities have more buildings with glass exteriors. Birds often see sky in reflection off glass during the day, confusing the window with sky. Some nocturnal birds are attracted to artificial light; thus, the more artificial light, the more likely a bird will strike the building at night. Also, the more glass a building has, the higher the probability that birds will mistakenly strike the glass windows.

Frequency of collision also depends upon the time of year: Fewer collisions occur during winter. Many more collisions occur during fall and spring, which are migration periods. Birds are less familiar with building layouts relative to surrounding landscapes along a migratory route, thus the higher the chance of a bird strike.

Weather also affects the probability of a bird strike: The poorer the weather conditions, the higher the probability of a strike. Poor weather conditions force birds to lower altitudes and limits visibility. Low wind speeds affect lifting of birds to higher altitudes.

If you have ruled out the above, then a possible effect is space weather that has affected the bird. Space weather events that occurred over the last few days and today may be impacting the bird and the bird erroneously strikes windows. Read on to better understand space weather and space weather effects on birds.

Space weather effects on Birds

Space weather is defined and described in the AstroPictionary YouTube video shown below. Since birds

are found on Earth, space weather is effects to Earth’s environment that birds are within; the source to a space weather event is most likely due to an event associated with the Sun: When the Sun has an event such as a solar flare or Coronal Mass Ejection (CME), it blasts charged particles into space. If Earth is in the path of this blast, then Earth will be subjected to a space weather event; as the blast of charged particles from the Sun takes several days to reach Earth, Earthlings can prepare for the impending onslaught.

One example of a space weather event on Earth is a geomagnetic storm. During a geomagnetic storm, Earth’s magnetosphere is disturbed. Sometimes Earth’s skies show beautiful aurora like that seen in the image below over Ringvassøya, an island in Norway.

Caption: Image of aurora courtesy of Svein-Magne Tunli under CC BY-SA 4.0

When Earth’s magnetosphere is disturbed, Earth’s usual magnetic field line locations are also disturbed; Earth’s magnetic field lines can change direction, for example. Since birds navigate by these magnetic field lines, space weather events that affect Earth’s magnetic field will affect a bird’s navigation. For example, homing pigeons often get confused and go in a wrong direction. Some homing pigeons never make it home; some take several days to weeks to return home. In 2008. NASA detected a massive breach in Earth’s magnetosphere by large solar winds, which resulted in enormous geomagnetic storms that likely affected birds and animals.

To determine if a space weather event is occurring or is predicted to occur, you should check out the Space Weather Prediction Center. The Space Weather Prediction Center (SWPC) is a laboratory and center of US National Weather Service and part of the National Oceanic Atmospheric Administration (NOAA). The 30-minute prediction of any aurora, intensity of aurora, and location of aurora can be found at this link to NOAA’s SWPC. Shown below is an example of what you will see at the center: In this case, we see a <50% probability of aurora occurring over Canada, Greenland, and Iceland.

NOAA also makes predictions to Earth’s geoelectric field due to any geomagnetic storms. This gives a prediction to the effects on Earth’s electric power lines, for example, and which areas of the United States are affected. The stronger the geomagnetic storm, the more states at lower latitudes are affected. As shown in the graphic below, as Florida has been impacted by a recent geomagnetic storm, the space weather event that hit Earth must have been highly energetic!

Caption: Snapshot of NOAA live Geomagnetic Field 1 minute 3D model

The main page of the SWPC at NOAA, like that shown below, gives a lot of data. Locate the “G2 Moderate Geomagnetic Storm WATCH Valid for 14 Apr 2022” in the center of the graphic shown below. The white arrow block that points to the G2 MODERATE Geomagnetic Storm Watch is informing the reader that a geomagnetic storm will likely occur on 14 April 2022. With the date of the graphic being Tuesday, April 12, 2022, as shown in the upper right, NOAA is giving a couple days warning. As explained in the white chevron arrow, a solar flare occurred on the Sun that sent charged particles in the direction of Earth. Earth will be impacted in a few days. As such, any homing pigeon races occurring in a couple days should be postponed so owners don’t lose their prized pigeons forever.

At the time of writing this post, Earth has been experiencing several geomagnetic storms. As these storms have been strong, states in North America as low in latitude as Florida have been affected. Birds navigating via Earth’s magnetic field lines in Florida may be confused in their travels; as such, these birds may collide with glass windows. Some birds like robins may squelch nocturnal travels and extend day travel activity when geomagnetic storms occur, other songbirds like chiffchaff and dunnock do not seem to alter their nocturnal or daytime migratory patterns during such storms2.

How To Minimize Bird Strikes to Windows

First thing you should do is analyze your outside areas. Move any bird feeders and/or bird baths away from any nearby windows. These relocations may help minimize bird strikes to windows.

One way to minimize bird strikes to windows is to line windows with a patterned film, which acts like a warning system. Bird tape, as it is called, is translucent but does obscure some of your view to the outside. The image below shows an example of a dotted grid pattern film that has been attached to th windows; bird tape has been shown to be a deterrent to birds striking windows. Notice the reflection of sky in the image that could be confusing the bird and a source to a bird’s strike.

caption: Image courtesy of Panek under CC BY-SA 4.0

Another inexpensive option is self-sticking stickers that are placed a few centimeters apart on windows. These stickers have also been shown to be deterrents to birds striking windows. Instead of stickers to the inside of a window pane, a netting attached to the outside can act as a deterrent.

Another option is to add exterior shutters to your windows or awnings. Birds will see the shutters or awnings and navigate around. Although effective, this option is expensive. A slightly cheaper option is to add exterior screens, which are good at keeping not only birds out but bugs as well.

Another example of a deterrent is adding UV absorbing film to windows. Birds can see UV band light but humans cannot. A one-way film that absorbs UV light allows humans to see though the window to the outside; birds on the outside of the window would see an opaque window, which is a window that appears dark from the outside or reflective from a silver colored film; opaque windows deter birds from striking.

The image below shows a human being subjected to UV light. The human is wearing a UV absorbing film on one side of his face, the side labeled ‘Sunscreen’; the other side of his face has no UV absorbing film. The sunscreen acts like the UV film applied to a window in this example: A bird flying towards the human would still see a face; however, one side would appear darker (i.e., left side of face in image) compared to the other side, which appears brighter as the face reflects some of the UV light. Since humans can see in V band light, the human would appear in normal ROYGBIV colors, but with one side of the face more reflective and brighter than the other. The reflective UV light would help deter the bird from accidentally striking.

caption: Image of human bathed in UV light courtesy of Spigget under CC BY-SA 3.0

An alternative to a UV absorbing film is UV reflective film. UV reflective films applied to the interiors of windows reflects UV light on the exterior of the window while allowing visible light to pass through both ways. Humans cannot see UV light and so humans would not notice UV light from the Sun reflecting off the exterior of the windows. Birds, however, can see UV reflected sunlight, which would look like a bright spotlight coming from the window. Like UV absorbing films, UV reflecting films also act as deterrents to bird strikes.

As nocturnal birds are affected by artificial light, install motion detection lights. Instead of lights that remain on all night in your garden or on your house that may cause nocturnal birds to continuously circle or otherwise not continue on their travels, consider installing lights that only come on when motion is detected. In addition, select blue or green colors, which are less disorienting to nocturnal birds than white, red, or orange colors.

If the cause seems to be a space weather event, then just wait a few days for the space weather effects on Earth to dissipate. Try adding any film that has a repeating pattern every few inches to deter birds from flying into your windows. For example, consider adding a simple spray paint like snow to your windows or soaping up your windows as a temporary deterrent for birds that are temporarily lost. For the short term solution of soaping windows, you will have to add more soap as the bubbles dry; however, this option is very inexpensive. The bird’s internal navigation should return to pre-space weather conditions after the event, once again navigating around your house.


  1. Wynn, J. et al., 2022, Science, v. 375, i. 6579, p. 446
  2. Bianco, G., Ilieva, M., & Akesson, S., 2019, RSBL, v. 15, i. 13

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About the author

Michele M. Montgomery earned a B.S. Degree in Nuclear/Mechanical Engineering from the Pennsylvania State University, an M.S. Degree in Physics from The University of Alabama with a concentration in Solar Physics, and a Ph.D Degree in Physics from Florida Institute of Technology with a concentration in close binary star systems. She joined the faculty at The University of Central Florida Physics Department in 2004 where she regularly taught astronomy, astrophysics, and cosmology. In 2006, she noticed that a large, urban college nearby to UCF did not teach astronomy at one of their largest campuses. She began teaching astronomy at this East Campus of Valencia College, a college that has more than 60,000 students; she still teaches four courses of astronomy each fall, spring, and summer semesters. The astronomy program atValencia College East has grown significantly with several more faculty added who teach astronomy.

By 2019, Dr. Montgomery has taught astronomy to more than 10,000 college and university students, both online and face-to-face. Many of her students have gone on to take her astrobiology, astrophysics, and space physics courses. 

By 2016, Dr. Montgomery had co-authored several astronomy texts and quiz/exam banks. Her work appears in several domestic and international astronomy text books (e.g., Horizons by Cengage, Universe by Cengage, Foundations of Astronomy by Cengage) that are used both at the higher education as well as at the high school levels. Starting in Fall 2019, Dr. Montgomery switched gears to authoring digital textbooks and research full time, while still teaching 12 courses of astronomy and up to eight conceptual, algebra, and/or calculus-based physics courses each year. Her research interests are numerical simulations using Smoothed Particle Hydrodynamics of close binary star systems. She also regularly is granted telescope time on the NASA's Kepler space telescope for observing eclipsing binary star systems. She has also observed using Gemini South, Keck, and Kitt Peak ground-based telescopes. Her major teaching areas are Astronomy, Astrobiology, Astrophysics, Cosmology, Space Weather/Space Physics.