Why Do Cardinals Fly Into Windows

Why Do Cardinals Fly Into Windows? 8 Ways to Stop Them

Reports say that about one billion birds die each year after flying into windows in the US alone, and cardinals are among the most common victims. Even if the bird was lucky enough to cheat death, it’d probably live with permanent injuries in the skill, bill, or wings. Why do cardinals fly into windows? There are three reasons:

  1. Cardinals may be attacking their reflections, thinking that another bird is invading their territory.
  2. If the window is crystal clear, cardinals may think they’re flying into open space.
  3. Cardinals that recently ate fermented berries may be too disoriented to see the mirror.

That was the short answer, but I’ve got way more to share on this topic. I’ll analyze all the reasons why cardinals fly into windows, and I’ll also share some ways to protect them.

3 Reasons Why Cardinals Fly Into Windows

do cardinals kiss

Technically speaking, you can skip directly to the solutions in the next section to learn how to protect cardinals from striking your window. However, understanding the underlying causes will allow you to devise your own solutions if the ones I’ll present don’t prove useful.

1. They’re Attacking Their Own Reflections

In case you haven’t already realized, the protagonist of the Angry Birds game is a male Northern Cardinal! This game’s creators couldn’t find a better species to embody the angry bird leader in the war against the nasty pigs.

When the mating season rolls around, male cardinals become super aggressive toward other birds, especially other male cardinals.

If a cardinal spots an intruder inside its territory, it’ll sound a series of warning songs first. Most intruders will back off after hearing this call because they know that cardinals shouldn’t be messed with.

When a cardinal stands in front of your window, it falsely perceives its own reflection as an intruder. And since the warning call won’t shake off the imaginary rival, the cardinal will start flying and pecking at the window until it gets injured.

Photo by Tina Nord

Cardinals Turn Peaceful in the Winter

Although cardinals don’t typically live in large flocks, their territorial instincts gradually fade away as they move into wintertime. It’s extremely common to see a group of ten male cardinals scouting your backyard for seeds during that time.

Of course, as soon as cardinals begin to accept other males into their territory, you should expect the window accidents to happen less often.

2. They Don’t See a Physical Barrier

I’m pretty sure you’ve seen hundreds of videos capturing unlucky people as they dash through glass doors. If the glass can deceive intelligent humans, birds surely don’t stand a chance!

Author Note: If your window is reflecting dense outdoor vegetation, cardinals may think they’re flying through a clear path. If you keep some potted plants right by the window, cardinals may feel tempted to go explore that untapped territory.

Photo by Skyler Ewing

3. They Might Be Disoriented

Cardinals, and all birds for that matter, have an excellent spatial perception, which is why they can weave through dense branches without breaking a sweat. However, that ability might become impaired for two reasons: eating fermented berries and looking at glaring lights.

Getting Drunk on Fermented Berries

As you might already know, cardinals aren’t picky eaters. They love to feed on a broad selection of seeds, fruits, and even insects, but berries are among their all-time favorites.

As berries become over-ripe, their sugar content doubles up, paving the way for fermentation and alcohol production. Because cardinals have tiny bodies, eating a few of these fermented berries can make them, well, tipsy! Yes, birds do get drunk!

That phenomenon becomes especially common after the first frost. The actual date varies according to your location, but it generally happens between September 1 and December 13.

The good news is, cardinals will sober up on their own. But if you happen to catch a drunk cardinal, you can put it inside a dark box until it soberizes. This way, you’ll be protecting it from dashing into windows or becoming a helpless prey.

Getting Distracted By Bright Lights

Birds use stars to navigate the sky, especially while migrating. But if they have to pass through busy towns, they might get distracted by street lights, lit windows, car headlights, etc.

Luckily, cardinals don’t migrate too far from where they were born. Besides, they usually head to their sleeping locations once the sun goes down.

However, if a predator wreaks havoc on their nest during the night, the cardinals will have no choice but to fly away, and that’s where accidents may happen.

7 Ways to Prevent Cardinals From Flying Into Windows

Photo by Skyler Ewing

Alright, now that we’ve explained all the possible causes behind these unfortunate accidents, let’s see how you can protect those precious birds from facing imminent demise.

1. Tape Your Windows

Attach 1/2-inch duct tape on the outside surface of your windows to make them more visible to birds.

For the ultimate results, make sure to pick a bright color that can be clearly visible from a distance, such as red, orange, and light green. Black tape won’t work because windows already look dark from the outside.

Author Note: After determining the color, now it’s time to think about the spacing. You can run vertical stripes spaced no further than 4 inches. On the other hand, horizontal stripes should be placed 2 inches apart.

Why these measurements in particular? Well, the average size of cardinals is 8 inches, meaning that they can squeeze themselves through any gap wider than 6 inches. So you should always make sure that the untapped areas of your windows are narrower than 6 inches.

2. Attach Some Decals

Although taping your windows would do the trick, it won’t look stylish. Instead, you could opt for colorful decals.

However, keep in mind that attaching only one decal won’t cut it. Like I said earlier, cardinals will think they can squeeze through the clear parts of your window if they’re big enough.

Put up as many decals as you can fit on the window. Then use your palm to evaluate the clear areas. If you find a gap that’s bigger than your palm, cover it with tape or another decal.

And again, those decals should go on the outside surface of your windows — that’s where they can really break up the reflection.

3. Attach a Fine-Mesh Netting

If you’re into DIY projects, you could have some fun implementing this idea.

Grab a fine-mesh netting, preferably one that’s made of polypropylene. Then, attach this netting to a wooden frame that’s slightly larger than your window. Finish by attaching this frame 2 inches away from your window by using shelf brackets.

Some people mount the netting directly over the window. Although this may make the window more visible to cardinals, it doesn’t actually make use of the netting.

When you mount the netting far away from the window, birds can safely bounce off it without hitting the glass. You’ll be basically creating a fancy trampoline for those cute birds!

4. Use Frosted Privacy Films

If you don’t mind covering your windows for the whole mating season, the Rabbitgoo Privacy Film should be your best bet.

These films will make your windows look like solid brick walls, making it highly unlikely for cardinals to fly into them. Better yet, the films can reflect 84% UVA rays and 99% UVB rays, which should make your house much cooler during the summer.

Once the mating season wraps up, you can easily take the films off your windows without having to deal with any sticky residue.

5. Paint the Windows with Tempera Paint

What Do Baby Cardinals Eat

If your kids like to paint, you can let them nurture their talent on the windows with tempera paint.

Author Note: The best thing about tempera paints is that you can easily remove them with soapy water. Plus, they don’t flake or crack with heat, meaning that they’ll last throughout the mating season.

Remember, the clear gaps between the painted patterns shouldn’t be bigger than 6 inches. Otherwise, cardinals will keep crashing into them.

6. Install External Shutters

If you want a permanent solution, consider installing electric external shutters. Keeping those shutters closed when you don’t need the sunlight will surely put an end to bird accidents.

Awnings and sunshades will technically block the external reflection, but cardinals may still fly into the window if you have indoor plants. If you still want to go with awnings, consider pairing them up with internal curtains or blinds.

7. Relocate Your Bird Feeder

If you have a bird feeder in your backyard, place it within 3–4 feet away from your windows.

This way, birds won’t gain enough momentum before hitting the window, which should minimize the risk of serious injuries.

8. Turn Off the Lights

As I said earlier, cardinals might mistake a lit window for a star when flying during the night. Always turn off the lights before leaving a room, or close the blinds whenever possible.

Photo by Chris F.


Cardinals are naturally territorial, so they’ll fly into windows if they perceive their reflection as another cardinal invading their territory. When the mating season ends, they may still dart at windows if they can’t realize there’s a physical barrier blocking the way.

To solve this problem, you should make your windows look opaque, or at least break up the outdoor reflection. You can use duct tape, decals, tempera paint, or privacy films.

Fly high friends!


How do I stop cardinals from hitting my windows?

To prevent cardinals and other birds from hitting your windows, you can use decals or stickers on the outside of your windows, install window screens, use bird netting, close curtains or blinds during the daytime, move bird feeders away from windows, and plant trees or shrubs near windows to provide a visual barrier. These methods can help to make the windows more visible to birds and reduce the chance of collision. However, it’s important to be persistent and patient as it may take some time for birds to adjust to these changes.

Why would a bird repeatedly fly into a window?

A bird may repeatedly fly into a window due to several reasons such as mistaking the reflection of the sky, trees, or other birds in the window for a clear flight path, perceiving its reflection as a rival bird entering their territory, becoming disoriented by the reflection of nearby trees or feeders, being more territorial during breeding season, or being ill or injured.

Why does a bird peck at my window every morning?

A bird pecking at a window every morning can be caused by a variety of reasons such as perceiving its reflection in the window as a rival bird entering its territory, becoming more territorial during breeding season, looking for food, developing a habit of pecking at a window or being ill or injured. To stop a bird from pecking at your window, you can try to make the windows more visible to the birds using decals, stickers, window screens, netting, curtains, and move bird feeders away from windows. If the behavior persists, it’s best to consult with a local ornithologist or a bird rescue organization for further advice.

Comments 9
  1. We have a male cardinal flying in to our windows on all sides of the cottage. He seems to go to any room a person is in at the time.

    This has been going on almost 4 months -October to January.

    He flies gently into the window them hovers or slides to the bottom and hangs on for a few seconds looking in.

    I tried most things recommended but clearly this is not territorial dying mating season. The female is there in the background as well but not hitting windows.

    1. I have the same issue for about 6 months he goes to every window in the house but it’s not just him she does it too?
      I feel like they need something 😩

    2. We are having the same problem and it has been going on for 4 weeks now. The female is present sometimes but not always. One female flew so hard into the glass storm door she killed herself. I have tried decals and pictures, etc. Nothing deters this bird. I have lived in this same house for 40 years and have had plenty of cardinals and this has never happened before. This is driving me crazy and I don’t know how to help this poor bird. I do not believe in killing anything so that is not the answer and I don’t want this bird to kill himself. What to do????

  2. Mine is just the female and the male is back in the evergreen she keeps flyinto the window.. and looks inside for months

  3. I have a female that is constantly trying to come through the windows. Not violently. I’ve put bright pink post it notes up on all the windows she has a problem with. The male is around but he doesn’t attack the windows. This is a first and we have been here for years. I also feel like they need something.

  4. My issue is not with house windows. The red bird (aka Fred) is busy on my pickup windows. Every single window Fred pecks on and the mirrors and poop everywhere. Any suggestions to help there. No garage space to put in. Drives me crazy. Help!!

  5. In Sept. of 2020 my Mom passed away,then in April of 2021 a red female Cardinal started to knock on different windows it became louder each time for about 2 weeks and would not stop then in early May my sister called crying and said she had stage 4 pancreatic cancer ,she passed away 2 weeks later and the Cardinal has stopped knocking

  6. SAME HERE! Like even my little tiny master bathroom window that’s on the side of the house on the 2nd story. Scares the crap out of me. He was gone for a couple of months and came back this week.

Leave a Reply

Your email address will not be published. Required fields are marked *

Why Do Birds Chirp at Sunset? Know the Facts
Why Do Birds Chirp at Sunset

Why Do Birds Chirp at Sunset? Know the Facts

You might be used to the bird’s song at night, but what about the bird

Best Wood Sealer for Bird Boxes, According to Experts
best bird safe wood treatment

Best Wood Sealer for Bird Boxes, According to Experts

Whether you’re planning to build a birdhouse or a feeder for the birds in your

You May Also Like