I think any animal that can learn their name has some sort of intelligence. My first chickens that I kept in the house at night and on very cold winter days (like today) when in town, all knew their names, certain commands, like "time for bed", "get down", "up", "NO" and probably about 20...
I forgot to mention the red sexlink hen that rolls the dog ball, I dont use it at all in the winter, but she still "remembers" how to use it when I give it back to her in the spring/summer.
The other hen got killed in a dog attack this fall. They would have been four years old this coming...
Probably anyone that has chickens that have been highly socialized with humans will realize how smart they can be.
My red sex link learned how to use one of those rolling dog balls that has the holes in it that will spill out treats if you roll it. Her and her EE friend love to roll it around...