Based on the erotic manga by Akazawa Red.

What is the most fascinating thing you have seen an animal do?

The pet stories I’ve seen here are either similar to or better than the ones I could share,* so I’ll stick with a wild animal story, plus two small bonus stories. *Although one of my two cats, who loves having her face rubbed, has the cutest habit of gently petting my face when I’m petting hers, as if she’s trying to reciprocate.
Granted, she’s more likely to do it when she’s hungry and trying to cute me into feeding her, but still. Main story: I lived for many years in a very rural area with a LOT of deer, and a lot of windy hilly roads.
Deer cause a lot of accidents in that area; hitting a deer generally results in a totalled car, and sometimes in the death of the driver/passengers.
Oh, and the deer too, sometimes, although often they’ll be the ones to walk away.
Since I drove home most days during the times that they were mostly likely to be out and about, their status as a serious road hazard has largely ruined any cuteness factor that they once held for me. On a typical night, during a 20 minute drive I’d have to brake 2–4 times to avoid hitting a deer.
One evening at dusk, on my normal drive home, I saw a deer crossing about a hundred yards ahead of me, so of course I slowed down—a cardinal rule in deer country is that if you see one, you should expect another.
I looked to the side of the road that the deer had crossed from, and sure enough, there was not one but two deer about to cross the road. But as I got a bit closer, I saw the oddest behavior.
The one that had crossed went back to the edge of the road, waiting for the other two, with concerned ears.
The larger of the two that hadn’t crossed yet was in front, blocking the smaller of the two… and I saw it very carefully looking both ways on the road, spotting my car, then herding the smaller one back away from the road! It’s hard to describe the exact movements, but it was just like a human mother teaching her children how to cross the road safely.
As I passed them (at about 5 MPH), I saw all three watching me, patient but not panicked, and once I was past them (by about 15 yards) the two looked both ways AGAIN, then finally crossed, with the larger one herding the smaller one. For those who don’t spend a lot of time dodging deer on roads, this might not sound too impressive, but it was the first time in my life that I ever saw a deer do this; usually their approach to crossing a road is more like just flailing their way across at varying speeds with their eyes focused on the other side of the road, hoping for the best.
After seeing the crossing guard deer, I kept a closer eye on deer road-crossing behavior, and though I never noticed any looking both ways again—and a good 90% of what I saw was clearly the run-for-it-and-hope approach, or the amble-slowly-and-stupidly-across-with-utter-disregard-for-jammed-brakes-and-honked-horns approach—I did start noticing that about 10% of the deer made a habit of running along the side of the road, parallel to traffic, then popping across once the traffic was gone. Deer are even more dangerous than I thought.
They’re LEARNING. Bonus stories: An animal that does not seem to learn, at least not when it comes to roads, is the wild turkey.
They’re also a major road hazard, but we had one male in the area who was even more in need of the ability to learn than most.
The males are very territorial, and this one made the particularly bad mistake of claiming a stretch of road as his territory.
The speed limit along that stretch was low enough that this didn’t result in the turkey’s death, but it sure resulted in a lot of annoyed late drivers who had to slow down to 3 MPH while an enormous angry bird strutted around on the road and flew aggressively at them, attacking their windshields and tires. The title for the most hilariously human expression I’ve ever seen on an animal’s face has to go to a coyote.
(Yes, there are coyotes in VT.
And coydogs.
And coywolves.) Before I built my much fancier compost bin, I just had more of a compost heap behind my garage with chicken wire around it.
In order to get to it, I would walk along the side of the garage, then turn the corner.
One afternoon I was walking out to the heap, and rounded the corner just in time to see a youngish coyote pawing through my compost.
(No, there was no meat in there.) The coyote looked up at me, and froze, with its paw in mid-air.
Oh, how I wish I’d had a camera: I had no idea coyote faces could be that expressive.
It was the guiltiest, oh-crap-you-saw-me, kid-caught-with-his-hand-in-the-cookie-jar expression I’ve ever seen in my life, on any animal, including humans.
Completely frozen, with staring at me with wide eyes and dropped jaw, then the ears started to slowly wilt, the eyes started to swivel left and right, the tail started to droop, all with that paw still frozen in mid air… it was like a live cartoon.
You could practically hear the ‘Yipe!’ Imagine a blend of these images: Since I know that coyotes can be dangerous in pack form, I followed my first instincts for a second or two by going right back around that corner and picking up my trusty pick-mattock, but curiosity got the better of me and I rounded the corner again, only to see the coyote hightailing it for the hills in a panic.
Except its tail was a lot closer to being in between its legs than being held high… I built a nice sturdy 60″L x 32″ D x 36″ H three stall bin of pressure treated lumber and heavy duty wire mesh not too long after that.
(Kept out the coyotes; didn’t keep out the groundhogs.)