Wednesday, March 10, 2010

Bird Mortality and Science Denialism

An article was published yesterday on the Mother Nature Network re: bird collisions with windows by Nature Conservancy bird expert Dave Mehlman. While the tragic number cited in the article isn't new to avian enthusiasts, it's disheartening to read comments posted by the incredulous and ignorant.  Apparently, they would like to know where the scientist got his data from other than his own gluteus maximus. It's not enough to be skeptical that one billion birds may be killed in North America each year from colliding into windows, I guess it's also proper form to be exceedingly mean-spirited. Notice I said "may" in the preceding sentence because if one were to do a little digging, this staggering number comes from a US Fish & Wildlife fact sheet where it states "may account for … deaths each year."

Check out some of the comments (some have been deleted):

"A billion birds! LOL That would be....well no math skills here but that would be like hundreds of birds hitting windows every *second* ....that would be like a scene out of Hitchcock with literally stacks of birds that we'd have to push aside from our doors to get to work."

"The billion number is completely asinine not to mention the incredibly wide range of '100 million and 1 billion.' a 1 to 10 ratio? let's say the # is true...that would be a billion more birds in the air if we try to save some with these many more plane crashes via jet engines, how much more bird crap on newly washed cars."

"It has been my observation most of the birds that hit my picture window do so around the time of the vernal or autumnal equinox. Maybe it has something to do with the angle of the sun at this of the year. My picture window faces the north and doesn't usually have shades down the way that the other windows do."

"This guy obviously learned math at the school of Numbers I Just Pulled Out Of My A**. This might be believable if there were dump trucks of dead birds being piled up with nowhere to put them. I thought science was supposed to be objective."


"Aren't there around 300 million people in America? So wouldn't that mean that every single one of them would have over three birds a year killed at a window close to them? A family of four would have 14 birds EVERY year killed at a window on their home? What kind of idiot compiles these statistics? Certainly not a math major. Worse, who gives these people credibility?"

"All this time I thought it was the wind turbines generating electricity that were killing the birds. Sounds like another environmentalist wacko who won't be happy until we are all living like it's 1800. If a bird is too stupid to avoid a window, then Darwin was right."

"Oddly, at the age of 46, in my entire life I have yet to see a single bird actually killed by a window collision - barring windshields, of course. I've lived in rural, suburban and urban settings. I have witnessed a grand total of *perhaps* 6 window v bird instances in that 46 years, and in every one of them the bird simply flew away afterward, albeit a bit less enthusiastically. Since Mr. Klem and the author of this piece of reporting seem so convinced, I would certainly like to see how Klem came to his number totals. Did he personally see a billion birds kamakazi into windows and expire, or did he perhaps see one or two and multiply them by a random figure he pulled dripping out of his nether orifice? Inquiring minds want to know."

"I'm not ankle deep in dead birds here in a major city. OK so there are some birds that fly into glass. Boo hoo. Who counted all these dead birds? And how many of the dead birds are simply pigeons that had been poisoned? I walk down city streets among tall buildings and I don't see a bird on the sidewalk or street. WTF kind of idiot writes this stuff? And WHO TF is the idiot that gives this any publicity at all, even on the internet? How about I write an article about Martians kidnapping my canary?"
What a bunch of fallacious piffle.

Dead birds collected from Toronto during migration (

It's an irrefutable fact birds die from window collisions, especially during spring and fall migration when tens of millions of birds are on the move during the night. The question we would like answered is just how many perish this way. Since there's no conceivable way to collect every single bird that dies, we have to rely on making a reasonable estimate and perform data modeling in order to discern the scope of the problem. This has already been done. If these impish critics were to have actually followed references cited by the author, they might have found this paper (complete with its own references) by Dr. Daniel Klem's on his website stating:

"Researchers differ in their evaluations of the magnitude of the toll that glass exacts on individual species and bird populations overall. Before much was known, annual deaths attributable to windows were hypothesized to be 3.5 million in the 1970s. Since then, extensive studies over the past three decades have been used to estimate the annual toll to be between 97 million to 975 million birds in the U.S. alone. The wide-ranging difference among these figures attests to the complexity of attempting to determine accurate amounts from a source in which every individual bird is a potential victim and sheet glass of every size is a potential killing site in the environment. The roughly 100 million to 1 billion toll is based on the assumption that 1-10 birds are killed at one building in the U.S. each year. Another independent study produced similar results, and evaluated this current range of annual mortality figures to be reasonable. This confirming study examined records of 5,500 volunteers who optionally recorded bird strikes at windows while they counted visitors to feeding stations at their homes. To put these numbers in perspective, annual U.S. bird populations are estimated to be 20 billion in the fall, and annual glass kills are estimated to be 0.5 to 5.0% of this figure."

An independent confirming study with empirical data!  How about that?  It's a fact that North American songbirds are experiencing steep population declines. We can choose to ignore window collisions as a prominent cause of bird mortality, but then risk making a mistake when trying to put these population declines into proper context with the other causes. I guess we can't assume Americans actually care about the future of wild birds in our country.  Science denialists come in a variety of forms, all of which are devoid of credibility and virtue. Clearly, there's a lot of sarcasm, apathy, and general mistrust of the scientific community out there, especially when it comes to environmental issues.  Where does that come from, I wonder?