Where I live in Montana hundreds of deer each year are struck and killed by automobiles and trucks. From what I can tell this has been going on since there have been cars around.
I have been able to avoid a deer strike myself by driving slower than the speed limit and watching for any kind of movement on the side of the road. I am especially careful when driving at night, but some amount of my good fortune is just dumb luck. My wife hit a deer and mangled the front of her SUV when it jumped out from a grove of trees. There was no way she could have seen it there.
I often see deer foraging on the side of the road and they don’t try to cross. But there have been many instances where it seems that one deer has successfully crossed the road but the rest of his group is stuck on the other side. One by one they try to cross the road and often times they don’t all make it.
Since we are weeding out the deer that make the worst decisions why aren’t deer becoming more wary of cars and trucks, or are they? It sure doesn’t seem like they are getting any smarter about this over time. Evolution should favor the ones that are natually more cautious and fearful of vehicles.
Eventually the deer should get smarter about roads and cars or die out. However that could take many hundreds of years and by then our mode of transportation could change bringing new challenges to wildlife.
Then you need to consider that places like Montana are so vast that deer may not see cars and trucks up close very often.
Q: Why did the chicken cross the road?
A: To prove to a possum that it actually could be done.
Mortality from cars may not be very large relative to other causes of death when averaged over the entire population. Some percentage of the population may rarely cross highways. There thus may not be a very strong selection pressure to avoid cars.
Behavioral changes to avoid cars may be detrimental in some other way, such as making them so jumpy anywhere near cars that they feed less. Or they may make them more vulnerable to predators.
There hasn’t been enough time for selection to have a major effect on the entire population. Cars have been a threat for only about 100 years, compared to the deer’s evolutionary history of millions of years.
I live in a place called Hidden Valley Lake in SE Indiana. There’s about 1,800 homes in my neighborhood, we have lots of trees, some lakes and our own herd of deer that are not allowed to be hunted but get culled by hired hunters every year to keep the herd population in check.
These are the smartest deer WRT cars and avoidance of them I have ever seen. They see a car, they wait until it passes before they cross the roads. I have seen mothers teaching their fawns this. Once they start crossing they almost always do it in a single file line and if a car comes while more than one are crossing in this manner, they may stop for a second and assess, but then they continue to cross.
Its the weirdest thing I have ever seen. They are also really used to being around people. I get them in my yard all the time and I can get really close to them before they bolt.
So I am not totally sure how this fits into the OP. I guess I am saying that even dumbass animals like deer can appear to learn to adapt to their environment. The fact that this is all in a residential neighborhood helps with its slower speed limits. On the interstates, sometimes there’s just no avoiding them if they run right out in front of you. Usually 18 wheelers get a lot of them around here on the freeways as there’s a lot of furry, bloody bundles of rag-a-bones littering the shoulders.
It seems this is just the does and fawns. All bets appear to be off with the bucks, which, when fully grown, don’t ever seem to stop moving. Every time I have seen one they are usually running.
Behavioral changes like this will happen much more rapidly due to learned behavior than due to selection for genetic changes. And whether deer learn such behaviors may depend on the frequency of encounters with cars, and whether there is some clear positive reward for avoiding them or negative one for not doing so but surviving. (If a deer is hit by a car and killed, obviously it can’t learn itself to avoid them in the future.)
My observation is the same – they are very stupid, skittish animals. I was once speeding, then decided to slow down, and at that moment, a deer ran in front of me, slower or faster and I would have hit it. If it heard my engine, or my wheels screech, it still ran toward the hazard. They have simply not been under a selective pressure to avoid these sorts of threats.
I looked in my rear-view mirror to see another crossing behind me. Most animals are more cautious than that around unfamiliar incidents. But the second deer just didn’t see my vehicle as a threat. I don’t really get it: my Jeep is faster, bigger, louder than a bear or mountain lion. Its made of metal, and smells like burning petroleum, something that doesn’t occur naturally. I guess, its so out of the ordinary, it probably just looks like the scenery.
Their only understanding is that something big will chase them and kill them, so they’d better run like hell instead of standing around reading the “Deer Xing” sign.
I think the rats would be insulted by the comparison.
Deer are kinda like chickens - being the dumbest they can possibly be and still continue to exist. And like Chickens, they basically exist to be food. Only, we got rid of the stuff that ate them, which leaves us.
First, evolution takes time. Automobiles have only been around for, what, one century? Not enough time to override millions of years of deer evolutionary psychology.
Second, Montana is different from most of America (larger, emptier, more wide open spaces). As it is, there are loads of deer who are thriving in suburban settings. A modern American suburb is like Deer Paradise! After all, humans in the suburbs have driven out all the deer’s natural enemies, and they’ve planted nice yummy lawns and flower gardens for the deer to eat. Heck, we even WATER those lawns and gardens all year.
In much of America, we’ve created ideal conditions for deer to live and breed in. So, even if X number of deer get run over by cars and pickup trucks, the population is bound to stay high. People don’t run over nearly enough deer to offset the population boom we’ve made possible. Even “dumb” deer who don’t avoid all the cars going by will probably live long enough to make babies.
I don’t believe behavior is an influence in evolution, is it?
Perhaps adults could learn to stay away from roads and teach their children, but that isn’t passed on genetically.
I think this is key. I’m not sure what part of Montana dolphinboy is from, but here in Carbon County we have a population density of 3 dwellings per square mile (yes, I said “square mile” not “acre”). There are quite likely deer that have never set foot upon a road.
The last population survey I saw estimated that there were 35,000 deer in the county, and 10,000 people. I do see dozens of dead deer along the road each year, but dozens doesn’t even make a dent in a population that size.
I was going to suggest we’re likely to see behavior change in small animals like squirrels since they’ve had more generations than deer since the advent of the car, but looking it up I’m surprised to learn whitetail deer must be pretty dumb - they don’t live longer than gray squirrels outside of captivity, and only 1/3rd to 1/5th as long as their bigger cousins, moose. Guess there’s too much stupid to have been affected much in 20 or so generations of deer.