Leading Scientist Calls On Bluebird Lovers To Protect Birds.

February 1, 2021

Mr. Bernie Daniel
President
North American Bluebird Society
P.O. Box 7844
Bloomington, Indiana

Dear Mr. Daniel.

We have lost about one-third of our birds over the last 50 years. That is why I am writing to ask you to launch an organization-wide effort to provide safe homes for bluebirds by promoting the installation of systems to protect against bird-window collision deaths. Your past successes in recovering the bluebird population show that you can make a major difference.

For the past 47 years, I have been studying, writing, and teaching about bird-window collisions in the human-built environment. There is now a broad scientific consensus that sheet glass in the form of windows in all types of human dwellings cause many bird deaths, Eastern Bluebirds among them. We also know that more birds die striking residential home windows than any other type of buildings, including the large number of dramatic collision kills that occur at urban skyscrapers periodically covered by media reporters. Single-family homes are estimated to cause 44% of window collision mortality, which is between 1/3 of a billion to a billion birds dying each year in the U.S. alone, billions worldwide.

Most often, we humans recognize an opening in a human structure is covered by glass. Birds do not. Scientific studies have repeatedly confirmed that clear and reflective windows are invisible to birds. They are killed hitting these invisible barriers trying to reach habitat seen through or reflected on their surface. Only by uniformly covering a window with an effective strike-deterrent pattern will birds see and avoid it. Research also has repeatedly validated that effective strike-deterrent patterns consist of elements separated by 2” in horizontal rows or 4” in vertical columns. More restrictive, smaller spacing between elements, offers even more protection. The science about bird-window collisions also reveal that one out of two hits results in an outright fatality. Those birds that initially survive a strike to fly off are known to die later from life-threatening injuries. Just how many die after flying off is still an open question, but given what is known about the severity of collision injuries the suspicion is grim with few being able to complete their migration or retain and maintain good health on their breeding and non-breeding grounds.

It was not enough for us to identify the immensity of the problem. We had to find solutions. They have been found. Aesthetically pleasing effective collision prevention options cost between $2 and $ 30 for a typical window. The best source for information is “The Consumer Guide to Window Collision Prevention” which I have endorsed https://ornithologycenter.com/sdm_downloads/consumerguide/. This site only shows scientifically validated collision prevention options. The common option of placing a bird shaped decal or two on the window does not work because its presence does not alert a bird to an invisible lethal window barrier.

Without applying the life-protecting pattern coverage to windows, birds attempt to fly through, and most often die trying.

I cannot put it any better than the advice you give your members:

Putting up a nest box is a responsibility that should not be taken lightly. When you put up a box, a commitment is made to provide as safe a place as possible for bluebirds to raise their young.

Therefore, I urge you to launch a bluebird community wide effort – like designating a “Window Collision Prevention” month – to focus the bluebird community on the imperative of protecting our birds from window collision deaths. There are resources to help you deliver this message at http://aco.muhlenberg.edu/, and personal assistance is available and welcomed from my research colleague Peter G. Saenger (psaenger@muhlenberg.edu).

Sincerely and respectfully yours,

Daniel Klem, Jr., Ph.D. D.Sc.

Sarkis Acopian Professor of Ornithology and Conservation Biology

Muhlenberg College

Allentown, Pennsylvania 18104-5586