I think hand raising birds may be "fine" as long as the birds are raised around other birds. Birds hand raised alone are going to have more problems weaning than birds raised in groups. Birds that continue receiving socialization with their own species even after weaning may be less likely to imprint on humans than those that don't get that kind of socialization.
I just finished reading one book and started another. Both mentions that the critical socialization period of puppies is 4 and 12 weeks of age (or before 12 weeks in age) and (first book) the critical period for kittens is the first 7 weeks of life. It's not that they can't be socialized after this point, just that it's most effective during those specific weeks. The critical socialization period for parrots has not been mapped out - probably specifically why is because birds wean and mature at different weeks in age. A budgie could wean at 6 weeks and be mature at 6 months, however a macaw may wean at 2-6 months in age and be mature at 3-7+ years in age.
Not only do animals (in general) need to be socialized with a variety of humans, but they also need to be socialized with other animals at a young age. If they lack this important socialization period, it can lead to aggressive or scared adult animals. (
FACT: Colts raised alone without other horses around become rapist stallions as adults.)
Puppy Socialization | Fur and Feather Works, LLC - Dog Training and others!
With parents, we often buy hand raised individuals and take them home shortly after they are weaned. After the birds are weaned, many do not get socialization with other animals or birds, or maybe humans besides those that visit the home. We then end up with hormonal birds that think they are humans and choose favorites in the household. Often times these birds do not get along with other birds of their own or similar species once they are adults and haven't been around other birds.
Charlie, my mitred conure, lived with a man for about 10 years of his life. He's definitely a one person bird in the sense that he takes a while to warm up to new people. He's not a people bird, so he doesn't like strangers, but if someone were to work with him and earn his trust, then he'd willingly go to them without clinging to me. In his foster home he did bond with a lilac crowned amazon but in my home he has not bonded with any other birds. When I got him he was terrified of dogs and would scream his head off if he heard a dog barking. I don't know why.
(in contrast, my first conure was afraid of cats, and for good reason! he was previously attacked by a ferret, so to him all small furry creatures were probably scary. He didn't mind [med/large breed] dogs, however.)
Jayde, my red throated conure, I believe was raised in a family setting and seems to take a preference to older people. She is an attention whore! Loves it when people pay direct attention to her, and it doesn't have to be physical attention! She also seems to prefer women over men, which could be because women really do "baby talk" more so than men, and that's the kind of attention that she eats up. She's sat on my shoulder while begging for attention from someone else, and has even flown to another person to get attention from them. As far as I know, she has never bonded with another bird. She seems ok with dogs, less so with cats.
My conures do not get along. They can tolerate each other, and they do squabble and bicker, but they are not friendly towards each other.
It's often recommended to not house different sized species together because often the larger species could seriously hurt the smaller species... yet, in the wild, various sized species co-habituate without issues. If you look at the "macaw clay licks" for example, you may find macaws eating clay with amazons, pionus, conures and orange cheeked parrots. That's quite a size difference between species! And yet, you rarely ever see a wild parrot with a nasty, bloody injury caused by another parrot. In captivity, well, things don't work out quite as well...
It is rather interesting though that humans prefer hand raised birds over parent raised birds, and yet when it comes to other animals such as dogs, cats, horses, etc we purchase animals that were parent raised. (A bull raised by humans can be a danger to humans as an adult.) All other animals are allowed to be raised by their parents and are socialized with humans. It could be a difference between big boned creatures vs slender bonded creatures - in that slender boned creatures tend to be more flighty and afraid than big boned creatures.
Although I mentioned that hand raising may be "fine", I still think there may be other methods to raise birds that could potentially result in better adults.
Co-parenting Experiences with Companion Sun Conures
Concepts in Behavior: Section II - Early Psittacine Behavior and Development (read part about Socialization and Co-parenting)
Taming Parent-reared Orange-winged Amazon Parrots by Neonatal Handling
Ethical, Moral & Spiritual Considerations of Companion Parrot Care (interesting and thought provoking article in itself - page 4, last two paragraphs talk about the behavior differences in african greys clipped or not clipped at an early age)
Hand raised birds can indeed make great pets, however there may be some unwelcomed behaviors due to it. Most people want dependent birds that hang out with them all the time, when in reality an independent adult is probably a healthier bird, mentally speaking. Parrots are flock creatures, they were not meant to be "alone".
