Just saw a report on the evening news saying that the general bird population has decreased about 25% in the last 30 or 40 years. Then I vividly remembered when I was a kid (50’s & 60’s) driving cross country with my parents and seeing the state of the front of the car. It was litteraly covered with bug corpses. Gas stations even sold bug screens that covered the grill and headlights. I recently had a chance to do this again and couldn’t help but notice how few bug splats were on my car and other interstate cars I saw along the way.
Could the apparent decrease in bugs be responsible for the decline in the bird population or could something else be at work?
Modern cars have gotten much more aerodynamic in the last 20 or 25 yrs going from a coeff. of drag of ~.5-.6 to around .35 -.4. Could this account for the difference in bug splats?
Losing birds is one thing but losing bugs is a much more serious problem. Anyone have any insight on this?
The decrease in bug splats has been noticed by many people and is known as the Windshield Phenomenon. The meaning of it is unclear, but many researchers think it points to a real decrease in insect populations.
The loss of insects certainly contributes to the loss of birds. However, the loss of habitat is probably the biggest problem. Both insects and birds decrease when habitat is destroyed. Every time you see a new subdivision or new highway built, it’s a loss of habitat. It’s especially bad if those are built on previously unfarmed land. I’ve been doing lots of research lately involving looking at various parts of the US and Canada with streetview and see a lot of this happening. It’s depressing.
This seems like it would be pretty easy to test. All you need is a classic car collector–or better yet, a group of them, at a convention or a car show.
Just ask them to show off their stuff, and drive for an hour or two.
Then follow alongside in the next lane with a bunch of modern aerodynamic cars.
Then count the bug splats.
A recent study showed a loss of 3 billion birds in North American since 1970.
The study wasn’t designed to investigate causes, but in a CBC Radio interview one of the authors blamed environmental changes and particularly human encroachment on bird habitats.
It’s funny, different searches can give very different results from different sources. My previous claim of 6 billion birds in North America was based on a result that said 3 billion birds was a population decline of 29%, or about 1/3, which would leave behind about 6 billion.
But then there’s this search, which says 10-20 billion birds in the US alone.
Still, your abcbirds source is claiming up to one in ten birds in the US killed every year by window collisions. That seems awfully high. :dubious:
I’m not sure if I can find the study I read a while back, but someone did try test this. The gist was that there is a small difference between modern cars and classic cars regarding number of bug splats, due presumably to aerodynamics (though driving habits are also likely to have changed), but not nearly enough to account for the differences recorded. You’d need to look at it for much longer than an hour though, seasonal differences and weather can have huge effects on short-term bug numbers. But yes, classic car owners are also reporting a big reduction in bug splats.
It’s backed up by other studies of invertebrate numbers as well, so it’s not just a car thing.
The concern is less absolute numbers than disproportionate impact on certain species, particularly raptors. Soaring hunters like buteos and eagles [are extremely vulnerable](https://bioone.org › volume-52 › issue-1 › JRR-16-100.1 › JRR-16-100.1.pdf). There have been a variety of attempts to mitigate these impacts but it continues to be an ongoing problem. Beyond just hurting those species, disruptions to the populations of apex predators like the above could potentially have a variety of downstream and unpredictable ecological impacts.
