Turning Off Home Lights Saves Birds? NO Scientific Justification
Jim Cubie Ornithology Center at Muhlenberg College
As part of the Lights Out campaign homeowners are urged to save birds by turning off a few home lights. This way, it is claimed, they can help save the “500 million to 1 billion birds killed by window collsions every year.” The phrase “turning off a few home lights can make a big difference” keeps showing up in outreach material. Since it defies common sense, I traced this quote, “turning off a few lights at home can make a big difference” all the way back to its source at Cornell Lab. When asked the question, “How could this be?” I was referred to the Van Doren paper. It is the only study showing that light management in a building can reduce window collision deaths. His text says that it applies to low rise buildings with large window spaces and with lights which are often on all night. It does not apply to homes, with a few lights on for few hours. I confirmed this in a phone call with him. (fn 1.)
If homeowners think that they can help birds by just turning off a light, why would they install a permanent system?
No outreach document should deliver the message that turning out home lights saves birds anymore than a doctor should tell his patient that exercise will cure his cancer. There is no scientific basis for either claim
I urge the Lights Out campaigns to deliver this message: “while we are working hard to prevent bird collisions downtown, the best way for you to help is by installing bird window collision prevention in your home. As many birds die hitting home windows as die hitting low-rise buildings.” A few local campaigns are delivering this message.
For information about these scientifically tested systems which protect against bird window collsions see the “Consumer Guide to Bird Window Strike Prevention.” FN. 2
Home lights should be off — or on motion detectors — all year, to save insects.
Wrong Information Causes Real Harm.
It may be said, “but it does no harm” if we tell people to turn off lights at their homes. That is wrong. It does cause harm. If you advise a friend that he use natural treatment for cancer, but he needs chemotherapy, your advice certainly harms him. He dies. It is the same if we advise people that they can save birds by turning out lights in homes. Birds die — thousands of them. These birds would have been saved if we had convinced homeowners to install permanent window collision prevention systems. If the Lights Out campaign convinced 100 homes to install bird window collision prevention, it would save 2,000 birds over the next 10 years – twice that if they feed birds.
Home Lights Out – zero saved;
Permanent Installed Systems – 2,000 birds saved.
No ALAN Effect. It equally defies common sense that turning off a home light – even two thousand home lights – can have any effect on the over all light level above a city. In Chicago, there are 250,000 street lights and about as many again in the surrounding cities. The 250,000 street lights in Chicago emit 2,250,000,000 lumens. Note that is a “B”- billion. Add to that all the other lights in tens thousands of buildings. If a campaign convinces 1,000 bird lovers to turn off two (2) security lights, and they in turn convince a 1,000 of their neighbors to do the same, the lumen reduction is 0.0267% of the street lights. How many birds will be saved?
Drivers of fatal bird collisions in an urban center; Benjamin M. Van Doren,1 , David E. Willard, Mary Hennen, Kyle G. Horton , Erica F. Stubera, Daniel Sheldond ,Ashwin H. Sivakumare , Julia Wanga, Andrew Farnsworth, and Benjamin M. Winger. PNAS 2021 Vol. 118 No. 24 e2101666118, https://doi.org/10.1073/pnas.2101666118
Footnote 2. For information about these scientifically tested systems see the “Consumer Guide to Bird Window Strike Prevention.” It includes a description of all the scientifically validated systems, compares prices, compares the effect on vision out the window of options and includes DIY directions for all.https://ornithologycenter.com/sdm_downloads/consumerguide/
Contact: Jim Cubie Ornithology Center at Muhlenberg College Jim Cubie1@gmail.com