Bird migration is on: Are your windows bird-safe?
46% of deadly bird-window collisions occur at homes and other buildings under four stories high
Bryan Lenz, who helped make Milwaukee Bucks’ Fiserv Forum the world’s first bird friendly arena, turns his attention to home windows and shares his tip for easy, inexpensive and effective fixes
WASHINGTON, D.C. – Nearly half of Wisconsin’s birds migrate for winter, and we can help give them a happy homecoming this spring by preventing them from colliding with a home window that’s been a problem for birds in past years.
Up to 1 billion birds die every year in the U.S. when they fly into windows, and nearly half of those at buildings of three or fewer stories, the majority of which are homes.
“Window collisions are a conservation crisis where everyone can quickly make a difference,” says Bryan Lenz, a leading national expert on bird-window collisions who has Wisconsin roots and was a featured speaker at the March 24-25 Bringing Birds Back conference in Oshkosh.
“I challenge everyone who reads this to make at least one window bird friendly,” says Lenz, now Glass Collision Program Manager for the American Bird Conservancy based in Washington D.C.
A UW-Madison graduate, he was previously the director of Bird City Wisconsin and chief scientist at the Western Great Lakes Bird & Bat Observatory in Belgium, Wis. While in Wisconsin, he worked with the Milwaukee Bucks to see them use bird-friendly glass in their new arena, and with Madison Audubon to encourage the City of Madison to adopt bird-friendly glass requirements for new large buildings.
Lenz is now turning his attention to collisions work where all of us can make a difference: home windows. “You can’t ignore the collisions at home and expect to really do the best you can to address this problem,” he says.
“My main message to a homeowner is, you can do this and you don’t have to do all the windows to make a difference. Just try one.”
Windows on buildings one to three stories high cause 46% of bird-window collisions and buildings 4 to 11 stories are responsible for 54%. Buildings 12 stories or higher account for less than 1 percent of the collisions; a single building that big can individually kill a lot of birds, but there are not a lot of buildings that big.
“Another positive thing about working to address collisions at home is you don’t need permission from anyone. It’s your house, it’s your window, if you want to do something, you can fix it,” Lenz says.
Most homeowners or tenants will know which window the birds hit and which needs to be tackled first. Windows across from bird feeders or bird baths and picture windows or sliding glass doors are also top candidates to address, he says.
Windows near bird baths and bird feeders often are bird-collision threats. Golden-winged Warblers, like the one perching on the edge, are super-colliders. They fly into windows at a rate disproportionate to their low numbers. Photo: Ryan Brady
Why birds collide with windows
Birds collide with windows because the glass is invisible to them. Reflections of trees, flowers and open water appear to be habitat the bird can fly through. “To a bird, reflection is reality,” he says.
Windows without a strong reflection may still be a problem if birds have a clear view to a window on the other side of the house where habitat or sky is visible. Glass railings pose a problem for the same reason. Newer construction can pose more of a problem because modern energy efficient windows are often more reflective.
Research has shown that bird-window collisions are a problem year-round, but that spring and fall migration are the worst times for such collisions because there are more birds flying around. The toll during fall migration is the highest, reflecting that bird populations are the highest in the fall, after young birds hatched in the spring make their first fall migration, Lenz says.
Some easy, inexpensive and effective fixes
American Bird Conservancy has tested hundreds of products for new construction or to retrofit existing buildings to understand which are effective at preventing bird collisions. None are guaranteed to bring collisions down to zero, but they will reduce bird strikes if used correctly.
Lenz says the research all points to a few rules for effective fixes for retrofitting home windows:
Solutions work best on the outside of the window
Solutions applied directly to the outside of windows should be spaced 2 inches apart for horizontal or vertical lines to deter hummingbirds and other very small birds from trying to maneuver through those small spaces to the other side
Solutions applied directly to the window should be light colored if the reflections are dark. For glass railings outside or if the window is reflecting sky, dark colors are best
Decals and stencils applied directly to the outside of windows with nontoxic Tempura paint or oil-based markers can be effective if spacing of 2 to 4 inches and color rules are followed.
Other inexpensive, easy-to-install products proven to prevent bird strikes on existing homes include:
Full-window external insect screens, which many Wisconsin homes already have, or bird screens that can be purchased and applied to the exterior window with suction cups.
Feather Friendly, rolls of adhesive dots applied to the outside of windows.
Acopian Birdsavers, a curtain of parachute cord that hangs in front of exterior windows, that may be purchased or made following DIY instructions on the website.
Bird Divert, adhesive dots that can be applied. Free samples are available through the website.
Patterns placed directly on the outside of windows, like this Feather Friendly product, can help prevent bird collisions when habitat is reflected in windows. The patterns should be spaced 2 inches apart to prevent hummingbirds and other small birds from trying to maneuver between the spaces. Photo: Jeff Sweet
What to do about problem windows that are hard to reach
Most bird-window collisions happen low to the ground because birds spend most of the day at the height of trees or below them, Lenz says.
If people can’t reach a problem window on a second story or higher, there are a few options. The best is to call a house painter, window washer or contractor who can use a ladder to install products discussed above.
If that isn’t possible, turn window blinds at an angle so it creates a bar for birds to see. These might be hidden by reflections and not work, but it is easy and could make a difference, he says.
Or, they can put one of the retrofit products on the inside of those windows to try to prevent bird crashes – but remember, the product is going to need to be bolder when you place it on the inside so it shows through the reflections.
He suggests running a test first: place a few sticky notes on the inside of the glass, and then go outside at several different times during daylight hours to look for the sticky notes.
“If you can see them from the ground, it’s likely birds will too at least part of the time, which is better than nothing,” he says. People can then follow the general rules regarding spacing and color.