Although actually a farm pest, I’d put the crow as the smartest.
A crow was recently observed trying to get a grub our of a rotting log. After a few unsuccessful minutes, the crow flew away and returned with a piece of wire. He then held the wire down with his feet and used his beak to bend and fashion a hook. He then used the hook to pull bugs and grubs out of the log.
I don’t ever remember reading about any other animal actually modifying something to make a more efficient tool.
As annoying as crows can be at 5:30 AM if you have a bunch near your house having a loud, er...”discussion”, it is hard not to admire them. They are very interesting creatures. My favorite story was related by a hunter:
Every year when he went deer hunting on his property, the crows would silently follow him around, making no noise, waiting until he bagged a deer and removed the gut-pack, after which they would swoop in for the feast. That part didn’t surprise him, he figured they knew a good thing when they saw it.
What he didn’t understand is how they seemed to know the exact day the hunting season would begin. When he would come out of his back door, ready to go, the crows were ready to go as well, sitting everywhere getting ready to follow him.
What the Hell...could crows read signs or calendars??? Then he realized one year, that they figured it out by watching him through his windows. As soon as he started pulling out all of his hunting gear, putting it on his dining room table, waterproofing his boots, cleaning his gun and such, the word got out in the crow world: He’s almost ready to go...be prepared to follow!
I thought of mentioning dogs. I didn't grow up on a farm, but spent summers and holidays there. When in high single digits I remember a huge, to me at 8 or 9, bull which with his own enclosure who would approach snorting when I walked by. Little farm dog, orange guy, would come roaring to my rescue biting the bull at the heels. Mr Bull would walk off. I would have nominated dogs as the smartest, but someone would argue for cats. But both are farm animals in this context. Crows though, they're smart. Horrible voice.
My ex-FIL had a pet crow growing up that would follow him to school then be there when school let out and follow him home.
I’ve never paid much attention to them other than watch them chase hawks and learned something new the other day.
I throw out bird feed so my elderly father can watch the critters through the window. The other day there were a dozen dove, five squirrels, three chimpmunks and about a 1/2 dozen other birds partaking of the feast.
A crow landed about 50’ away in the yard and started walking towards the feed. Every single critter scattered to the wind by the time he got there.