Death by window strike – millions of birds die this way but you can help save them with these tips

Staci-lee Sherwood
2 days ago
7 min read

Updated: 1 day ago

By Staci-lee Sherwood

Every year billions of birds migrate from their winter home to their nesting grounds, and back again. For anyone who’s traveled long distances you know how exhausting and sometimes tedious the journey can be. When we travel to the same place we often use markers so we know we’re on the correct path. Birds do the same thing using a variety of navigational tools. Their flight paths might have been formed thousands, sometimes millions, of years ago by their ancestors using their own internal clock and cues. Sea turtles have a similar ability, being born with their own unique honing system. Modern life with tall buildings and reflecting glass windows have altered what used to be a long but relatively safe journey to one that is extremely dangerous.

The mystery of migration

Why do some birds migrate while others don’t? Some species travel just a few hundred miles while others travel several thousand miles over mountains and oceans. These are amazing feats of nature no human would want to do twice a year. It’s exhausting and dangerous with no guarantee a bird arrives alive. For mated pairs, it’s even more uncertain that both will arrive safely and able to breed and raise young. After breeding season the newly hatched chicks, just learning to fly, have the task of following in their parents footsteps. Unlike humans, birds don’t have a choice they have to follow flock.

Migration through New York City is called the ‘Atlantic Flyway’ from wintering areas in the southern U.S. to as far as South America. These species can travel to the northern U.S. or even the Arctic to breed. Then back down after breeding season. The ‘Mississippi Flyway’ connects birds traveling between South America to Canada through the Midwest of the U.S. Tens of millions of birds travel these two routes so it’s easy to see how many die hitting windows and buildings that didn’t exists a century ago.

Migratory birds have an internal clock that signals when and where to travel. While they inherit from their parents which routes to take they use several natural cues to guide them. At the start of their journey birds use the sun, the stars and the Earth’s magnetic field to steer them in the right direction. When they encounter storms they can be blown off course. Some will eventually get back on track when the storm passes, others seem to choose to stay where they landed (in south Florida we have a yellow-headed caracara living here for three years) and others die from exhaustion from an extended trip or landing where there is no food for them. Scientists still don’t really know how birds learn to migrate or how the ever changing climate and landscape will impact them.

Click here to read more about it

https://www.scientificamerican.com/article/how-migrating-birds-use-quantum-effects-to-navigate/

Red Knots have the longest migration well over 9000 miles each trip. They can travel from as far south as southern Argentina to breeding ground in the Arctic tundra

Black Skimmers mostly live year round in South America but some populations travel north to breed, from coastal Florida up to coastal Massachusetts

Swallow-tailed Kites can travel over 5000 miles from northern Florida to southern Alabama and Louisiana down to northern half of South America, mostly Brazil

Rufous Hummingbirds can travel 4000 miles to get to their breeding grounds. A miracle since they only weigh about .02 ounces. Their migration is from western Mexico up to their Alaska breeding ground. A few have made it to Florida to winter. Their lifespan is only 3-5 years so this is an extraordinary migration

What causes window strikes?

Birds have been around, what scientists refer to as the ancestor of modern birds, about 85+ million years since the Cretaceous period. Human made obstacles like buildings and artificial light are a very new but deadly obstacle birds have had to learn to adapt to. Artificial light comes in two forms, direct and indirect (skyglow). Direct light can be lights inside or outside a building that draws a bird to it. Skyglow is the cumulative effect of all light; from street lights and car lights to cell phones, store signs and building lights. This type light brightens the entire horizon. Nocturnal birds and owls end of disorientated by this because it interferes with their night vision making it harder to navigate and see prey. When your eyes are designed to see in darkness a bright sky is deadly.

New York City skyline in 2010, with more skyscrapers now. Just a couple of hundred years ago this landscape was open and filled with trees, flowers and ponds. A feeding ground and rest stop for weary migrating birds

Chicago skyline in 2006. For a bird this is a wall of glass and reflections

Many modern buildings in cities look like this, a giant wall of super shiny glass. At night the buildings are light up inside so nighttime navigation can be just as dangerous. Imagine being a bird flying into this and thinking you’re flying into the sky. Buildings like these cast a reflection that can be blinding. Unlike skyscrapers, lower buildings can reflect trees and vegetation making it seem as though they are flying toward a safe landing. Many buildings have parking lots from above look like ponds often causing birds, even huge flocks, to crash or strand once they realize they’ve landed on concrete not water. This building reflects another building but also the sky making it seem as if the bird need only to fly over the reflected image, not the actual building.

This is an excellent example of what birds see when the reflection is vegetation. It’s easy but deadly mistake. Photo credit: Minnesota Bird Coalition

Artificial lights confuses and disorientates birds (and sea turtles) often until they run out of energy and die

Death or injury from window strikes and light pollution IS something we can prevent. If we can send a man to the moon, we can and should figure this out.

By the numbers

It’s estimated over a billion birds die from window strikes, the second most deadly cause of death after outdoor cats. The NYC Bird Alliance research shows between 90,000 and 230,000 birds are killed in the city each year in these tragic often preventable collisions. Mortality rates are high and the types of injuries show varying release rates. A bird with head trauma is the least likely to survive while stunned birds have a release back into the wild rate between 40 – 60%. These are poor odds especially for something modern life has caused and has the power to rectify. As if that wasn’t bad enough, millions more die from the use of pesticides which kill them directly via aerial spraying and indirectly by killing or poisoning their food sources. It’s little wonder birds in general are in serious decline.

Click here to read the NYC Bird Alliance study from 2025 https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0306362

How you can help save birds

In 2020 a landmark piece of legislation was passed by the NYC Council called the ‘bird safe bill’ and in 2021 became NYC Local Law 15. This requires all new construction to be bird friendly to reduce death by collision. However it left a loop hole of the millions of windows already in place. New York City became the largest city so enact such a law. With millions of birds still dying from exempt windows there is a lot of work still to be done. If you wish to help birds in other areas contact your local Audubon group or bird rescue and get a bill like this started.

Click here to read more about the bill https://www.nyc.gov/assets/buildings/pdf/ll15of20_sn.pdf

Some companies have gotten on the bandwagon to help our feathered friends, even if the law was their true inspiration. Tri State Sun Control uses 3m Bird Strike Window Film ‘Our bird safety film has proved to be 100% successful. It is installed at the Philadelphia Zoo and Bronx Zoo and they have reported no fatalities since the bird safety film installation. The lines are specially designed to break reflections on the glass allowing the birds to see that there is an obstruction.’ If you are looking to make your windows safer for birds this could be an option.

Another solution

Project Safe Flight began in 1997 by founder Rebekah Creshkoff who noticed a huge crisis of birds dying from building collisions. This program is all volunteer and run by the NYC Bird Alliance. There is also a project safe flight/bird strike rescue groups run in Atlanta, Georgia by Birds Georgia and in Minnesota by the Minnesota Bird Coalition and in Chicago run by Chicago Bird Collision Monitors. These three states have millions of birds migrating every year and always need help.

If you find a stunned bird time is everything. Be very gentle but swift. It’s best to take any stunned or injured bird immediately to a rehab. If you are not near one this is the next best thing to do.

There are many other ways to help migrating birds, or any bird, stay safe while in flight. The following are things for both residential and commercial buildings. Some are very easy and inexpensive but the lives saved are priceless.

Keep bird feeders and baths away from windows
Remove plants from windows if inside, for outdoor plants keep trimmed below the window
Click here for several ideas on window treatments to reduce collisions https://abcbirds.org/solutions/preventing-collisions/
Volunteer with a local bird group to record and recover injured/dead birds, injured birds might be rehabbed and released. Get a group together to ask the building owner if they could reduce nighttime light or put a treatment on the windows. Education is key to changing people’s minds and behavior.
Contact your Congressional Rep at https://www.house.gov/representatives - ask they support and bring to a vote this bill H.R.3268 - Federal Bird Safe Buildings Act of 2025
click here to read the bill
https://www.congress.gov/bill/119th-congress/house-bill/3268
Click here for a guideline on making buildings bird safe https://www.darkskysociety.org/handouts/birdsafebuildings.pdf
Support and volunteer with these groups…or start your own. They all have volunteer groups that rescue birds from building strikes and educational opportunities for the community to get involved: