Clear, reflective windows are lethal to birds.
Scientists estimate that just in the United States, as many as one billion birds a year die after flying into windows.
The Audubon Society has calculated that about half of these bird deaths occur at private homes.
But the iNaturalist University of the Utah Bird Window Collision Project tried making windows bird-safe and found that about 85% of bird collisions can be prevented.
Some Fast Facts About Birds Flying Into Windows
A bird’s eyes and brain function differently from a human’s.
People can’t see glass, but even little children realize that glass is solid.
We all learn to detect glass from cues that tell us it is present. We are aware of glass because we see door handles, window frames, and our position relative to a building.
Birds never learn that glass is transparent but solid. They perceive reflections to be real.
They may fly into a reflection of the opening where they need to fly through brush, bushes, and trees.
When humans bump into a glass door, there is a very small chance that they will experience any kind of serious injury.
But because birds have small bodies and fly at high speeds, and their bones are hollow, flying into glass can leave them stunned, seriously injured, or dead.
Here are some important things to know for bird-proofing your windows:
- Citizen scientists have confirmed, not surprisingly, that continuous glass windows and glass walls result in more bird collisions.
- Having a fruit tree next to a window can increase collisions up to 1300%.
- Having any kind of tree within 30 feet (10 meters) of a glass window more than doubles the risk of bird strikes.
- Birds are more likely to hit windows in the late fall and early winter than at other times of the year.
- Highly social birds like cedar waxwings may have several birds hit the same window at the same time.
- Having the lights on indoors after sunset in late fall and early winter confuses birds so they don’t roost for the night. The more active they are at night, the more windows they hit.
- Not all birds are equally likely to collide with windows. Birds that migrate at night, such as sparrows and warblers, are more likely to hit windows at night. Birds that are used to flying through dense vegetation, such as thrushes, ovenbirds, and hummingbirds, are extra-vulnerable to collisions during the day.
- One- and two-story buildings get more bird strikes than high-rise buildings.
- Buildings with glass walls and windows in forest settings are especially dangerous for birds.
How to Keep Birds From Flying Into Windows
Now let’s look at 12 things you can do to stop birds from hitting your windows.
Lights at night confuse migrating birds. You can reduce window strikes by turning off lights you don’t need to be on all night.
This is especially important during migration seasons from early March to early June and from late August to mid-November.
Make sure that lights point down, not out.
Place grates, filters, or open plantation blinds over lights. Use warm light LEDs, rated under 3,000 Kelvins. Or switch to lighting activated by motion sensors.
Make sure your outdoor lights meet the International Dark-Sky Association’s Fixture Seal of Approval. There are wildlife-friendly light fixtures for both indoor and outdoor use.
Place tape strips on your windows
Another method of keeping birds away from your windows is reducing uninterrupted glass with strips of tape. Cut 1/4″ inch (6 mm) widths of white tape and place them vertically 4″ (10 cm) apart.
Or cut 1/8″ strips of black tape and place them vertically 1″ (25 mm) apart.
You could attach large window decals, sun catchers, or stickers to your windows.
In a pinch, you could use masking tape or sticky notes. Black flying birds silhouettes, such as live-sized stickers of owls or hawks, however, don’t do anything to stop birds from hitting your windows.
It isn’t enough to put just one or two decals on a window.
You need to cover the entire window with vertical tape strips that look too small for a bird to fly through.
If you don’t like the look of vertical frits on your windows, consider buying UV-reflective tape that is highly visible to birds, but that appears as just a slight tint to humans.
Place reflective dots on your windows
If you are looking for a more subtle bird deterrent for your windows than vertical stripes, consider covering them with a pattern of dots.
Birds will see a distortion of their own reflection that they won’t suppose is another bird crowding onto their territory. They won’t fight their reflection because they won’t know what it is.
Dots or reflective tape on your windows are noticeable from the outside, but they have greater aesthetic appeal than stripes. The experience from indoors is similar to looking out through a screen door.
It’s not like looking out through the clear glass, but at least you won’t have the regular thud of birds against your window.
The most widely available brand of this kind of dotted UV-reflective fritting is ABC Bird Tape.
This brand can be tinted to match the exterior of your home, or printed with small images to give your windows a unique style.
Install Zen curtains
Birds won’t attempt flying through openings that are less than 4 inches (10 cm) across or less than 2 inches (5 cm) high.
Zen curtains are decorative ropes that hang down in front of your windows and create openings less than 4 inches wide. They are installed outside, not inside.
Zen curtains perform the same function as tapes, dots, and decals, but they are easier to install, and they won’t block your view of your backyard.
Also known as Accopian bird savers, these protective curtains are available from retailers and are also something you can make for yourself.
Put up mosquito screens
Mosquito screens don’t just keep out bugs. They also can keep birds from flying into your windows.
There are several different styles of mosquito screens, but the screens that do the most to protect birds are made from dark polyethylene plastic.
Birds can see the dark plastic. And if a bird crashes into your window despite the screen, the flexible polyethylene plastic will cushion the blow.
You won’t need more than 30 to 45 minutes to install mosquito screening on a single window.
The Secure Screen brand has a roll-up and roll-aside system that has a built-in brush that cleans your windows every time you roll up the screen. You can customize Secure Screen so it fits your windows.
Install one-way transparent film
Birds can’t see clear glass. They can see tinted glass. A one-way transparent film allows you to see out, but your windows will appear to be opaque from the outside.
The one-way transparent film reduces the amount of light coming through your windows and lowers your summer air conditioning costs.
It is essential to clean your windows — no streaks — before you apply the one-way transparent film.
You will want to measure your window carefully so you don’t have any gaps. You will need for the film to be a one-half inch (12 mm) wider and taller than your window so you will have full coverage.
You will just trim the film before final placement.
Let the window dry thoroughly before taking the paper backing off the film to expose the adhesive. Dampen the entire surface of the window with water from a spray bottle to ensure better adhesion.
Use a bird net to keep birds out of eaves and open spaces.
Bird nets are most often used as a form of pest control. They keep birds off berries and fruit and vegetable crops. They can also be used to keep birds from flying into windows.
Bird nets for preventing bird collisions with windows need to be hung so they are taut about 3 inches (75 mm) in front of the glass they protect. They need to be made of durable polyethylene plastic to prevent injuries to the birds.
Clear polyethylene won’t stop collisions as well as black polyethylene, although it will be easier to see through.
The ideal size of the mesh for bird nets over windows is 5/8 inches (15 mm).
That’s small enough that birds won’t get their heads caught in the net but large enough to allow birds to spring off the net should they fly into it.
Bird nets can be mounted on storm windows for easy installation and removal, or attached to eaves with clips, hooks, or a staple gun.
Install external sun shades or awnings
Sun shades are “blinds” on the outside of your windows.
They can be cranked down to control reflectivity during the day in sunny weather and cranked up to allow more light in your home on cloudy days when the glass in your windows will be nonreflecting.
Awnings make glass nonreflecting. Birds can look into the window and see the blinds, plantation shutters, or curtains inside.
They will steer away from your windows. You can use awnings as protection for a shelf of shade-loving plants that form an interesting architectural feature while adding a layer of protection for birds.
Sun shades will need maintenance after dust or sand storms.
They can be vacuumed or cleaned with a feather duster, and then rolled up for cleaning the window glass behind them.
Place bird feeders and bird baths either up close or far away
Moving a bird feeder or a bird bath to within 3 feet (about a meter) of a window ensures that a misdirected bird won’t take off for a fatal collision with your window when they leave it.
Otherwise, moving a bird feeder or a bird bath at least 30 feet (10 meters) away from a window ensures that flight patterns will be directed away from glass windows.
It can also help to attach bird feeders directly to your windows. Birds will come in for a landing to test the feeder, and ignore the window behind it.
Hang up a string of loose feathers in front of your window
When birds are attacked by predators, usually only feathers are left. Birds that see loose feathers will fly away to avoid becoming the predator’s next meal.
Hanging up a string on which you have mounted 10 or 12 feathers in front of your windows will direct birds away.
You make a do-it-yourself feather deterrent with some feathers and some fishing line.
Tack the ends of the fishing line to your window frame. Or you can buy a commercial product called Feather Guard.
Install exterior window shutters
If you want to minimize the number of birds hitting your windows but there are times you want to take in the view unobstructed, install external shutters.
You can roll down exterior shutters to cover your windows when you aren’t at home, in extremely hot sunny weather, and during storms.
You can roll them up again when you want the view.
Installing shutters is a home handy person task that takes about two hours per window.
You won’t need tools any more sophisticated than a screwdriver and a drill. If you are installing shutters on brick or masonry, be sure to wear eye protection.
If you need illumination at night, use motion-sensor lighting systems
Artificial lights disrupt birds’ internal navigation systems.
They can fly around light for hours trying to get their bearings so they can continue their migration.
Red and white lights are particularly disorienting for birds, blue and green lights less so.
Sometimes you need nighttime lighting for security and property protection. In the spring and fall, at least, try using motion-sensor lighting systems for nighttime security.
There will be less disruption of migration patterns, and you won’t be advertising the presence of windows that birds can strike.
What to Do if a Bird Hits Your Window
If a bird hits your window, and it seems to be alive, don’t pick it up immediately, unless it is in imminent danger from a lurking cat.
Some birds recover in just a minute or two after their collision. If the bird doesn’t come around quickly, place it in a box with an open top and put the box in a quiet, safe place.
Check on the bird an hour later. If it is able to fly away, let it go. If it is injured, call your local wildlife rescue center.
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