Hello Biophiliac.

I've read a couple of published papers on this subject, one in Nature I think, can't remember the other.
I think what I'm about to write was accurate at the time of reading the papers. A friend of my niece is currently doing a research project on avian brains. Tbh, I don't know enough about biology to follow the stuff in the papers.
I think, chickens have the largest relative brain size of any bird/fowl.
There is a story that some American aeronautical engineers were frustrated by the inability of the flight computers in combat aircraft to make the same maneuvers as a bird.
As the story has it one engineer mentioned that if a bird can decelerate from say 30 mph to zero and land on a branch with perfect balance, jump and do a 360 turn and this bird has the brain the size of a very small walnut then we either need to examine the birds brain, or reinvent the computer.

Apparently it's not just the neuron density, it's the firing speed. I can't recall exactly how much quicker the firing rate is but it's double integers faster than humans. Bird brains are like a modern hyper threading multi core computer processor while ours, while powerful are like old main frame computers from the 60's.
There has been a problem with human interest in animal intelligence for quite a few centuries now. Firstly, there was no profit seen in it. The next problem was trying to define intelligence. The term is used a lot but there is no short definition.
Some scientists stopped making the rather pointless comparison between human and avian intelligence. You're then left with the possibility that in this case chickens could be just as intelligent as we are but with a different skill set that makes different demands on their brain depending on physiology.
That is getting into very hot territory. Very few people, let alone academics want to go down that route. You can imagine the outcry from the various institutions that have elevated man above the other creatures on the planet.
I think the chickens here are very smart. Their ability to adapt which I consider a major component of intelligence is incredible. I've seen incredible levels of cooperative behaviour with the tribes here. That I think is also a factor in intelligence.
Sry, going on a bit.

Mind you, I did join BYC to chat about chickens.