It’s just bad luck for birds that cities tend to develop in biodiversity havens. “The same things that make a landmass or an area good for people are also usually good for birds,” [Dustin] Partridge [director of conservation and science at NYC Audubon] says. “These long-term routines are ingrained over millennia … they are not just going to stop flying along the flyway because the city is here.” 1
In fact, because of our city lights, the modern city may attract a higher density of migrants today than the area did centuries ago. 1
What has never been a mystery is that our illuminated cities coupled with man-made structures make a fatal combination. Our bright skies draw in wild birds, and the hazards we’ve erected kill them. 1
Creatures once well equipped to meet the challenges of their environment suddenly face a world in which their fine-tuned behavioral adaptations are no longer adaptive at all. 2

*Sharp-shinned Hawk following a window strike. Image copyright 2024 by Mark Haindfield, used with permission.*

On one October night of 2023 hundreds of migrating birds collided with one building in Chicago. Volunteers with the Chicago Bird Collision Monitors (CBCM) collected 964 dead birds along with an estimated 80 stunned live birds.

While collision events as large as this are rare, bird collisions are not. The tragedy is that these events are preventable. Artificial Lights at Night (ALAN) can be disorienting to night-migrating birds. Once drawn into cities and neighborhoods, the combination of artificial lights and glass can become disorienting and deadly. A study found that turning off just half of the lighted windows during spring and fall migration could reduce bird deaths on Chicago’s lakeshore by 60 percent. 3

Humans “see” glass because humans understand buildings. Birds don’t see glass that way and will fly into windows and other surfaces that reflect the surrounding landscape or try to fly through glass that appears transparent and invisible. Collisions with glass occur year-round, day and night. There are simple steps to help make windows safer, including creating patterns on the outer surface, making glass appear opaque, or putting up physical barriers; make windows visible to birds. These methods, when installed properly, can greatly reduce window collisions. 4

A 2014 study by the US Fish and Wildlife Service and the Smithsonian Institution estimated that between 365 million to one billion birds are killed annually by building collisions in the US. 5 High-rise buildings are not the only culprits. Many collisions also occur with residences (1 to 3 stories) and low-rise buildings (4-11 stories). 1

A few low-cost solutions include 5:

Close blinds or curtains.
Window screens – when installed on the exterior of windows – are one of the most effective collision deterrents. They also keep bugs out.
Move interior plants away from windows. Visible plants may be perceived as habitat by birds causing the birds to fly towards the plants.
Create patterns on the outer surface. Closely spaced hanging cords secured above and below the window or even left to dangle can prevent many bird strikes. Ready-made films or tape of dots space no more than 2-inches vertically and 4-inches horizontally may be placed on window exteriors.
Move feeders and bird baths. Either place feeders on the windows or move feeders and baths within three feet of the nearest window. This prevents the bird from reaching full speed as they take off. Or move the baths and feeders more than 30-feet away to provide room to maneuver.

*Feeders away from windows. Image copyright 2024 by Jon Nylen, used with permission.*

Wildlife Rescue / Rehabilitation:

Iowa State University Contacts for Wildlife Rehabilitation: https://naturalresources.extension.iastate.edu/contacts/wildlife-rehabilitation/woodbury
Forever Wildlife Lodge and Clinic: https://www.facebook.com/foreverwildanimalrescue/ or (712) 898-8355, services available 24-hours per day.
Iowa DNR Wildlife Rehab List: https://www.iowadnr.gov/portals/idnr/uploads/files/wildliferehab.pdf
Saving Our Avian Resources (SOAR): https://soarraptors.org

References:

Breyer, M. Reflections of a Bird Collision Monitory. Audubon Volume 126, Number 1. Spring 2024. Available online as: The Surprisingly Long History of the Movement to Make Buildings Safer for Birds, https://www.audubon.org/news/surprisingly-long-history-movement-make-buildings-safer-birds.
Dugatkin, LA. Anthropogenic Evolution. Scientific American Volume330, Number 6. June 2024. Available online as: Humans Are Driving a New Kind of Evolution in Animals, https://www.scientificamerican.com/article/humans-are-driving-a-new-kind-of-evolution-in-animals/.
Wetzel, C. Turning Off Lights at Night Could Halve Bird Deaths on Chicago’s Lakeshore. Audubon magazine. Available online: https://www.audubon.org/news/turning-lights-night-could-halve-bird-deaths-chicagos-lakeshore, July 6, 2021.
Beilke, S. Mass Collision of Birds in Chicago Reminds Us of the Important Steps We Can Take to Protect Migrating Species. Audubon Great Lakes. Available online: https://gl.audubon.org/news/mass-collision-birds-chicago-reminds-us-important-steps-we-can-take-protect-migrating-species , October 17, 2023.
Reducing Collisions with Glass. National Audubon Society. Available online: https://www.audubon.org/news/reducing-collisions-glass.