I'm always hearing about cars hitting deers. In my neck of the woods it's cars hitting squirrels.
Maybe in your neck of the woods. I-70 in Pennsylvania has those Jersey barriers running all up and down the road, with no gaps or dips or anything.
One night at 4 AM I was driving down I-70 and right after a blind curve my headlights fell across a herd of deer in the middle of the freeway, all trying to figure out how to get past this stupid concrete barrier that's too high for deer to jump over. So of course I find myself slamming on the brakes and swerving the car through a wild stampede at about 50 mph. The car slammed into one of them. It rolled up the left side of the windshield and landed on the asphalt behind the car, like a soon-to-be-converted atheist in a Christian movie.
I pulled over, and was trying to figure out WTF to do, with an injured deer lying in the middle of I-70 struggling to move around. A minute later a beat up Ford F-150 came down the road, swerved around this deer, skidded around, and managed to come to a stop on the shoulder.
A scary-looking old dude jumped out of the car and ran over to me and this deer. He said its leg was broken and it was going to die anyway. Then he said he had a tire iron in the truck.
He fetched it and came back. As he approached, it was still wriggling around on the road and glaring at this old haggard dude, like Hank Schraeder in his last Breaking Bad episode. Then he bashed it in the head with the tire iron. It struggled to drag itself away and he bashed its skull again. Then it stopped moving.
We both managed to drag the deer off the road just as a cop pulled over. We explained what happened, and he decided, "OK, I don't see anything I really have to write up here."
All three of us ended up hauling the deer into the back of the guy's pickup. He must have been eating that thing for weeks.
But I digress. Most roads don't have dividers and animals can make it across if they can avoid the cars. But roads that are set up like the Berlin Wall are a problem. Animals like deer are going to evolve into two species separated by I-70.