Alex the Parrot was able to identify over 50 different objects, he could count up to six, knew 7 colors and 7 shapes. Alex also understood the concepts of 'same and different' and 'bigger and smaller'.
You can see him pictured here at the left.
Usually dogs get all the attention that cats haven't grabbed up first, with horses, dolphins and elephants in the running as smart animals, but pound for pound I think that birds take the cake.
Alex has been compared to a 2 year old human child in cognitive ability and temperament. He'd throw tantrums when he got frustrated. He used to slam the door of his cage when he got back from the veterinarian.
(apparently birds don't like going to the doctor either) :)
An excerpt from his last night on Earth:
"You be good. I love you." said ALEX
"I love you too." I replied. (this is Irene Pepperberg speaking, Alex's trainer/scientist/friend)
"You'll be in tomorrow?"
"Yes, I'll be in tomorrow."
That's eerie. It doesn't sound like the sort of conversation you'd expect to have with a parrot. Perhaps it's all contextual but still that's pretty impressive.
It also makes me pretty sad. My cockatiel never learned to speak but I know she was pretty smart herself. The sweetest thing, she used to call for me until I'd whistle back. They do that to check on their flock, you know? She'd worry about me if I was out of sight until I let her know I was doing all right, then she'd settle right back down.
Poor Alex. He died tragically young. He was supposed to live for another 20 years. Imagine if he'd had his whole lifespan to work on his science? He was learning simple math at the time of his death and he'd just started to show us that birds see the same optical illusions that trick our own eyes.
Alex told Irene that the line on the right is longer.