Junebugs and flies are pretty dumb, but it might be a stretch to call them animals.
For creatures with actual brains, I need to nominate killdeer. We wondered why mama killdeer lost so many chicks this spring… 'til we saw them sleeping in the middle of the road. Mystery solved.
Elizabeth Hasselbeck.
I opened this thread because I knew someone would mention sheep…
Sheep, like dogs, have different breeds and levels of intelligence. I own hair sheep (Kathadins & Dorpers) and they are very good at what they do- raise lambs. They are better at raising lambs than most humans are at raising humans. I get all warm and fuzzy about my sheep, and while I agree SOME sheep do incredibly stupid things, most have a good reason for the things they do, especially if they are designed to exist in harsher environments i.e, range sheep in the Western U.S.
Go to a sheepdog trial sometime (a good one- border collie style is best!) and you’ll see sheep outsmart dog and human both- not always but enough to make them worthy opponents.
Dogs, all dogs.
I mean what animal can be trained to go to the newsagent in the pissing rain to collect a newspaper it can’t even fucking read.
Cats OTOH just sit smugly watching this idiotic animal making a fool of itself, again
In support of the Basset Hound, an acquaintance of mine explained to me one of the ways the experts have ranked “intelligence” among dog species.
They put a blanket over each dog and timed it to see how long it would take the dog to get out from under the blanket.
The Border Collie, of course, got out in a nanosecond. The Basset Hound lay down and fell asleep.
My brother.
Yeah, agreed. If someone put a blanket on me, I’d be right there with the Basset napping!
I think that he doesn’t like what you fed him. He can’t figure out why you’re too stupid to understand that! LOL!
“If we pull this off, we’ll eat like Kings!”
I don’t know about the stupid part, but I can vouch for ornery. I had chickens for several years - they all lived a long long time for chickens. But that rooster was ornery. If I wasn’t carrying food, he wanted to fight.
They figured out how to “tell me” it was time to refill the feeder - they’d sit next to the bin where I kept their food, and would follow me all the way to the feeder (single file like a parade), to make sure I did my job. They also liked to come in and watch television, but always went outside to poop. Pretty smart for chickens.
Or a crow. My brain isn’t working too well, but that internet lecture series (Ted something) has a program on them.
I apologize in advance for the further hijack of this thread, but:
I probably shouldn’t be surprised that my Beagle, Boomer, is 72/79 on the list. He’ll be 18 in April (I really think he’ll make it, despite his ailments), and he continues to irritate me with his inscrutable behavior.
I also want to nominate for the OP those South American sloths that move so slowly and infrequently that moss grows on them. How the hell do they ever “get lucky” and procreate? What are South American sloth frat parties like?
Chickens definitely. But I nominate spruce hens. These birds are so dumb, you can shoot at them, have a near miss (as in it gets so close it ruffles their feathers) and they’ll STAY THERE! Yeah, they’ll look around a bit like “what was that? oh well must not have been important”. But seriously!
(and no I don’t hunt, despite being here 40 years, I"m not a “real” Alaskan, I find hunting/fishing/snowmachining HORRIBLY boring :D, this was observed way back when I was a kid “hunting” with my granddad, and later when I stupidly went hunting with a boyfriend).
Children are worse than dogs. Children will dash out in front of your car, only realizing you’re there oncel they’re directly in your path, at which point they freeze and stare at you like a deer in the headlights.
Ordinary humans respond to dangerous situations with a “fight or flight” reflex. Children only have a “freeze” reflex. I’m surprised children have lasted more than a year or two after the widespread adoption of the automobile.
Three of my favorite breeds are on that list. 
The fish aweoweo. They live in caves. They are bright red or bright silver and very tasty. I would aim my sling at them from outside the cave with difficulty because I was aiming around my head. I would often miss. On the first or the second miss, this bright red or silver fish would think: “he can’t see me.” and continue cowering against the cave wall. On the third miss the fish would rush out of the cave, often hitting my face mask in the process.
the website: Family Priacanthidae, Bigeyes
From my own personal experience : A guy who is “aroused”. 
You are probably thrown off by the stupid grin and odd jerky motions. Some of us prefer the term “single-minded.” In any case, I’m pretty sure I’m smarter than a chicken in … Huh, what? What was I saying? Sorry, I was thinking about boobs for some reason.
I have to nominate poultry. When I was a girl I grew up on a ranch. The chicken coop had a large uprooted stump next to it. When a hawk circled over, the chickens would shove their heads into/under the stump, thinking Whew! that hawk is gone now! Problem was, their bodies were still in full view of the hawk, who would swoop down and grab one of the unfortunate hens.
Secondly, I have been living in close proxmity to wild turkeys the last seven years. I have many acres of pasture that are fenced and cross-fenced with non-climb wire fencing. Flocks of turkeys pass through the pastures daily, eighty percent will hop over the fences with no difficulty, but the remaining twenty percent of the turkeys will run up and down the fence-line in a panic because they can’t figure out how to get over the fence-line. I’ve observed them in their frenzied attempts to find a magical opening in the fence-line for hours. “Oh, if only we could fly!” It’s very Gary Larson.