What Happens When a Bird Hits a Window?

by Stephanie Herman, Assistant Conservation Director-Wildlife Care Center

During June and July the Wildlife Care Center received 70 birds that had hit a window—and this is our “slow” season for window strikes because most birds have completed their annual migration to summer breeding sites. As this article lands in your mailbox, birds are beginning their fall migrations, and here at the center we’ll start to receive dozens of calls and admissions each day due to window collisions. This is a tragic and avoidable pattern that we at the Wildlife Care Center watch occur each and every year. Window strikes are consistently among our top five reasons for injury, and last year was number three, behind only cats and cars. We also know that we’re only receiving a tiny percentage of the birds injured by windows each year. The majority aren’t observed or found afterward, and many birds don’t survive that initial impact or the untreated injuries they receive from the trauma.

Red-breasted Sapsucker patient at WCC - window strike
This Red-breasted Sapsucker is suffering from a number of injuries from their encounter with a window: a fractured jaw, an injury to the left coracoid, and head trauma that has left them quiet and slow to respond. In this case, the jaw fracture is the most serious injury, because of how reliant woodpeckers are on the strength and structure of their beaks and skulls. Unfortunately, these injuries were too severe for this bird to recover from, and we ultimately opted to provide the bird with humane euthanasia to spare them from further pain and suffering.

In our work at the WCC, we often run into the perception that hitting a window is a minor thing for a bird to experience. We envision a quick cartoonish bonk and maybe a few minutes sitting stunned before flying off, no major harm done. I think sometimes we wildlife rehabilitators reinforce that notion by advising folks to wait and see if the birds who hit their windows “recover” before driving them to us. Although we’d prefer to see and examine any bird that hits a window, we continue to give this advice because some birds are truly only stunned, and it can be quite a stressful experience for the animal to travel to the center unnecessarily. However, the ability to fly off doesn’t mean that that the birds haven’t received life-threatening injuries that can still lead to fatality, which is why this is a practice that those of us in the wildlife hospital wrestle with, and frequently discuss changing.

This Dark-eyed Junco fledgling has subcutaneous emphysema, which means there is damage to their respiratory system that is allowing air to leak out of the air sacs and into the space underneath the bird’s skin. Although this bird’s injuries were caused by a cat, we see this symptom frequently in birds that have experienced collisions as well. Although this can look scary and be very uncomfortable, this type of injury does often heal well with treatment.

It doesn’t help that injuries from window strikes can have extremely subtle initial symptoms, even if they are quite serious and life-threatening in the long term. It’s true that a large percentage of birds that have hit windows are unable to fly away because they have serious head trauma that damages their balance, coordination, or awareness. Many also have a fracture or dislocation of the coracoid or clavicle bones, essentially the “struts” in a bird’s chest that the muscles pull against to flap and fly. Others, though, may be able to fly away despite their injuries. Because birds hit windows head first, we tend to see jaw fractures and eye injuries that might not prevent a bird from flying away but can make it impossible to hunt or eat normally. There are also injuries that can take hours or even days to show up, like swelling and bruising, or even injuries to the bird’s respiratory system that result in air leaking into places it doesn’t belong. These injuries might not be visible and won’t necessarily interfere with the bird’s ability to move right away, but can become very severe later on.

This radiograph of a Green Heron that hit a window shows a left coracoid fracture, an injury that is difficult to notice from the outside but can result in a bird being unable to fly. The bird is currently in care at the WCC and on cage rest as the fracture heals. We won’t know whether the heron will be able to fly and return to the wild for several more weeks. We have high hopes, though!

Ultimately, taking the time to bring a bird that hits your window into the center for an evaluation by our trained medical professionals is the safest option and is, in my opinion, worth the peace of mind even if we do send the bird home right away. But I also hope that as a society we can take this threat to birds more seriously, especially since prevention is truly as simple as properly treating exposed glass so that it is visible to birds, reducing light pollution, and using bird-safe designs in our new buildings. We make this plea regularly each and every year, and this migration season is no exception: go out and make at least one more window or light in your life bird safe! For more resources and details, visit the Bird Safe Building page of our website.

This Lesser Goldfinch is suffering from head trauma after hitting a window. Because their balance is affected, they are struggling to hold their head up in a normal position. Neurological injuries from window strikes can range from extremely serious to mild, and it isn’t always easy to tell the severity of the injury until we have provided a bird with treatment for several days. In some cases, extremely severe symptoms can resolve beautifully over a matter of hours with the right treatment. But in others, symptoms that seem mild at first can be so persistent that they can prevent a bird from surviving in the wild. In cases of head trauma, only time (alongside professional medical attention) will tell.