👍 This.
Note, though, that many residents who enter a general psychiatry residency with the intention of pursuing child/adolescent fellowships later opt not to. I have read that this is due to the very demanding interaction (and documentation trail) that is required for each case. You'll be communicating not only with your patients, but also with their parents, grandparents, siblings, legal guardians, teachers, principles, school psychologists, child psychologists, law enforcement officers, social workers, and the like. It's definitely a team-orientated profession! Best of luck.
Though just a hSDNer (so, therefore, I would have no idea), I also can't help but wonder if it's also because exposure to C & A are limited in medical school (unless one opts for an elective), while both (general) psychiatry and pediatrics are. I would assume that a medical pediatrics patient is a very different interaction than a psychiatric one, in that the medicine one leaves a person with a more "awww! cute kids! I love kids!" reaction. Then they just assume, to some extent or the other, that C & A psych patients will invoke the same reaction; however, once they actually have to deal with it in residency, they find out that the C & A psychiatry has a lot more frustrations are less "aww! cute kid!"-ness than just pediatrics. Did that make any sense?
I think it's an important point, too. Though I tend to think all kids are inherently cute, a lot of the ones that are in need of a psychiatrist struggle with aggression, violence, self-injury and are more defiant and non-cooperative than the many of their healthy peers; this would be more true of adolescents, I would think. Then when you throw in the fact that, though in many cases the parents are functional/concerned/otherwise good at it, you are going to also be dealing with a lot of parents who are ill themselves/dysfunctional/just want medication for the kids/the cause of the problem and, unless there is actual abuse (what's considered so by the state), there is nothing you can do about it. Schools can be just as awful, as well: they push for unnecessary medication, not accommodate all needs or put up a fight, etc. A lot of the time, I don't think law enforcement officials know what they are doing and may brush off the child as bratty or, in the case of the adolescent, in need of punishment. So, in many ways, it's not just that you have to communicate with everyone; but with a group of people that may or may not be looking out for the kid's best interest, which I'm sure brings its own layers of frustration. Or I could be wrong, that just seems to be the impression I've gotten.
EDIT: By the way, OP, just to clarify. To become a child and adolescent (it's the same fellowship for both) psychiatrist, you will need:
A BA or BS degree from an undergraduate college: usually 4 years
To go to medical school to pursue your MD or DO: 4 years
General/adult psychiatry: 3 - 4 years depending on what you do
A child and adolescent fellowship: 2 years
