When I stopped in Billings I was surrounded by a swarm of yellowjackets. Luckily, they weren’t after me. What looked like every insect in the Great Plains was smeared across the front of my car. Yellowjackets are scavengers and I had brought them lunch.
I thought about that trip when I saw an article proposing reduced speed limits to save a rare dragonfly. A biologist drove a truck at various speeds and watched the results. The faster she drove, the more dragonflies hit the truck.
Press coverage said “speed limits could save rarest dragonfly.” There are two problems with that statement.
First, most of you reading this already know that numbers on signs don’t have much effect on traffic flow. Second, what the study showed was the fatality rate for dragonflies impacting one kind of truck. If you looked at my car beside the others that crossed the Plains at similar speed you would see mine was a lot messier.
The body count depends on aerodynamics. Something about my car is bad for insects. Maybe because the grill is designed to suck in a lot of air for cooling. I expect a pickup truck would also be bad because the corners deflect airflow too abruptly. Air makes a sharp turn and heavier bugs go straight. The critical speed for dragonflies might be 60 for sports cars and 30 for semis.
On some beaches, speed limits are set for shorebird conservation. The idea is, people driving on beaches should drive slowly enough that birds can get out of the way. In my opinion, this is on firmer scientific ground. The safe speed for birds has little to do with vehicle aerodynamics. It is based on bird behavior. There has been a lot of study of the distances at which birds alert or fly away from humans and their pets and devices. Also, humans behave differently on beaches and our experience with road speed limits might not translate well.
I can’t say that any particular beach speed limit is good, but at least the truth may be out there.
In the less scientific direction, look to Colorado. A 2010 law doubled fines and reduced speed limits in wildlife areas. Or as I think of it, halved fines in human areas. That was an emotional act, like most speed laws, and it didn’t work.
As my city’s traffic engineer used to say in between recommending illegal stop signs, “people drive the road the way they see it.” When there are swarms of migrating tree swallows darting in front of my car, I drive slowly. When there’s nothing in sight, I drive fast.
A recent article from Texas discussed a plan to re-open a wildlife refuge road with a lower speed limit to protect ocelots. In my opinion that’s doomed to failure. Unless drivers see an ocelot, or have seen them on past trips, they’re going to drive it the way they see it.
There’s no such thing as a road that’s perfectly safe for wildlife. I’ve seen roadkill on a driveway in a wildlife refuge where nature-lovers drive 10 mph or slower.
There are times when you have to choose one side or the other. Promising anti-road groups that speeding tickets will be written does nobody any good, but it’s been government policy for decades. People will drive 70 mph on an interstate-type highway no matter how many consent decrees you sign.
Back in Billings, the yellowjackets cleaned my car while I filled up inside. I left them behind and picked up a new batch of bugs to feed to the paper wasps in Idaho.
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