CAGS are flock birds, and should not be raised in isolation. The more they get interacted with, and the more involved they are, the better they do psychologically.
They are as stubborn as a mule. Possibly more. The old saying down at the rescue was "Where there's a will, there's a gray!" Meaning if they get OCD'ed on doing something, they are gonna keep trying... (which is why, when they develop plucking disorders, it can be so hard to get them to stop.)
They also have tempers, and a beak like a scissors. You can tell when they are getting mad. Continue to push it at your own risk. They must be taught to control their tempers and their bite pressure. DO THIS AT THE YOUNG BIRD STAGE AND IT WON'T BE AN ISSUE. TRY IT WHEN THEY ARE HEAD STRONG ADULT BIRDS, AND YOU WILL BLEED. So, NOW is a good time to bite pressure train.
I taught mine to push fingers away rather than bite them when he doesn't want to do something...
Mr. Towel taught him that, sometimes, even if he doesn't want to, he's gonna. With a CAG you choose your battles wisely.
CAGS need more of a say in being handled, than, for example, a macaw, that needs more of a firm hand and discipline to keep them from running amuck...
A little reverse psychology goes a long way with these guys. Pushing them to do stuff makes them mad. TRICKING THEM into wanting to do it, triggers that birdie OCD and has them doing it all the time for you...
You get more from sugar with these guys. They'll come to you on their own when you are part of the flock.
These are the highest IQ birds. THEY STUDY EVERYTHING AND EVERYBODY! Which also means if they sense danger, they are outta there. Skittish at times. They need to be introduced to things to feel safe. Stuff has to be "explained" to them. Then they start to relax.
Skittish also means they can have a propensity to displacement bite (objects frighten them, and they bite you to call the object to your attention.)
Birds that displacement bite are not appropriate shoulder birds.
Skittish also means that they WILL fly off if spooked. So harness trained or clipped if this bird is going to be an "outside" bird. Otherwise they are on the number one most likely to get lost list...
A psychologically healthy CAG is curious and an instigator. They get into things. When they feel safe they mess with people, and other living things. They play practical jokes on you... They play with toys. Investigate things. Figure stuff out.
They tend to be stand-offish, and they want to be handled on their own terms. They do not tend to be cuddle birds until and unless they want that for the moment, and at that it tends to be in limited amounts. (Similar to most amazons in that respect.)
A not psychologically healthy CAG is the opposite. They obcess over every little thing. They turn that intellect against themselves. They cower and sometimes remain frozen for hours studying shadows on the wall... You can give them toys, but that's just one more thing to be afraid of, and pick yourself over.
Abundance weaning and fledging is a KEY factor in raising a psychologically healthy CAG. It's vital.
These birds are exceptionally awkward and clumsy when they are young. If you take away their flight capabilities before they develop their skills, they remain awkward and clumsy... and this leads to psychological issues later in life... a lot of these birds' problem stem from a basic lack of confidence. Bolstering that confidence makes a world of difference. INCLUDING PLUCKING. And that relates back to allowing them to fully fledge.
As is the need to feel "involved" and "a protected part of a flock." (Without a flock, a CAG is a sitting duck for predators, and they know it... there is nothing more stressful than "any minute now something is going to come and eat me!")
Weaning, of course, food is love for a bird. That's why feeding behaviors are so often the ultimate expression of love. And that's why FORCE WEANING leaves scars, and triggers "abandonment issues" with birds. Again, these relate back to plucking disorders and other psychological issues.
MANY OF THE BAD BEHAVIORS WITH THESE BIRDS RELATE BACK TO HOW THEY ARE RAISED. PLUCKERS AND PHOBIC BIRDS ARE CREATED... THE WILD BIRDS DO NOT ACT THIS WAY EVER!!! So, that is the responsibility you take on, when you take on a CAG.
And finally, if you use language in context, and appropriately with a CAG, actually teach them, they will pick it up in context and use it in context with you... Which really is the highest level of involvement with a CAG.
They're fascinating birds to work with.
I've had mine from the weaning process on. He's happy, well adjusted, will go to anyone for the most part. Seeks stuff out. And is more likely to pluck you than ever pluck himself.
And that's most of what I've learned about successfully raising CAG's over the past 15 years or so.