Splat!
Steve Mirick
https://www.refugeassociation.org/birding-community-e-bulletin
One section in the recent bulletin that was kind of disturbing was on the decline of insects. Perhaps something we can all relate to.....what happened to all the insects that used to hit our windshield?! :-( It's depressing to think of what our future will look like if insect declines continue.
SPLAT!
Then there is the “windshield phenomenon,” something the public has noticed in recent years. This refers to the observation at this season where fewer flying insects accumulate on our car windshields, grilles, and front bumpers compared to past decades. This phenomenon has been noticed particularly since the early 2000s. Yes, even drivers who previously cleaned their windshields frequently – and used up lots of windshield-washer fluid – are now noticing far fewer bug splatters.
This is all significant, since insects form the main diet of many of our common birds. And it’s not just in North America where this has been noticed. One 2004 survey in the UK by the Royal Society for the Protection of Birds (RSPB) found one insect collision per 8 kilometers driven, but a 2019 follow-up survey showed a 50% reduction in insect impacts. Similar trends have been observed in Germany and Denmark, where insect biomass and abundance have decreased over recent decades, particularly among flying insects.
If you’ve noticed fewer swallows, swifts, nighthawks, and flycatchers, maybe there’s something serious going on! We are unaware of road-associated studies in the U.S., but one long-term study in a subalpine meadow in Colorado, monitored for two decades (2004–2024) found flying insect abundance dropped by 72.4%.
Also, a study released last month out of the University of Michigan found that a 62% decrease in insect biomass over a half-century altered the morphology, survival, and breeding phenology of Tree Swallows. Years with low insect abundance led to the size (i.e., smaller) nestlings and adults. The study is summarized here:
https://www.pnas.org/doi/10.1073/pnas.2607714123
Some of this important data has been accumulated at archives of the Long Point Bird Observatory in Ontario. (Their swallow records stretch from 1969 to 2024, with insect counts running from 1977 to 2011.) But what is driving the insect decline remains an open question. The decline does not simply track rising temperatures, so that a heat factor alone cannot account for it. Still, one pattern stands out. The losses sped up in the 1990s, the same time when neonicotinoid pesticides came into general use.
You can read a piece on Tree Swallows and insect numbers by Sanjana Gajbhiye here:
https://www.earth.com/news/tree-swallows-are-shrinking-as-insect-numbers-collapse/
Steve Mirick
Bradford, MA
amy highstrom
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George DeWolf
Hi Steve et al.,
I'm a little late in getting to this one, but I felt compelled to respond. The decline of insects is quite disturbing.
The day before this was posted, Mike Thomas and I were together for the Squam Lakes Butterfly Count. Prompted by this year's noticeable decline in so many butterfly species, we found ourselves reminiscing about the old days. We talked about how, years ago, a drive down a country road in New Hampshire almost guaranteed that your windshield would end up splattered with insects. I mentioned that I still have an old can of Turtle Wax Bug & Tar Remover in my basement that hasn't been opened since the Clinton administration. Anyone over 50 probably remembers the dense clouds of insects that used to swarm around streetlights and porch lights—moths, June bugs, crane flies, dobsonflies, and countless others. I distinctly remember reaching a lit doorway and having to hurry inside just to keep a dozen moths from following me indoors. Even the vibrant firefly displays that once lit up my backyard meadow are now only a shadow of what they used to be.
There is little doubt that this quiet thinning of insect populations is having profound, far-reaching effects throughout the food web. It seems to me that insects are the foundation of so much of the natural world—serving as pollinators, decomposers, and a primary food source for birds, amphibians, reptiles, fish, and countless other animals. You don't have to be an entomologist or an ecologist to appreciate how damaging their decline can be.
George