By definition any bird breeding facility, that is operating by basic industry standards, is a bird mill.
Get the definition for a puppy mill and swap out dog for parrot. The parent birds are kept in barren cages their whole lives. No enrichments, just a perch, nest box, food and two parrots period for their decades-long lives. And most breeders seal off the sides with metal sheets so they can't see the parrots in the cages around them. Bird breeders don't want them to be distracted! They figure w/out distractions they'll just breed round the clock.
There are no baths, or if there are, they're only in cases where it's a warm climate and they get hosed down with the cage when it's cleaned. They can't bathe at will ever. These places are not set up for the comfort of the breeder birds. Breeder birds are just pieces of an assembly line. It's factory farming parrots.
The babies are taken from them before they're weaned so these breeder birds have nothing. The vast majority, of all kinds of species, are featherplucked.
That's a parrot mill and any breeder with pairs of breeder birds living without toys, baths, a large enough cage to be comfortable (they keep them in the smallest cages possible. Less room to move = closer proximity to the mate & supposedly = more sex. Not. And smaller cages = more room for more breeder pairds.
These hard conditions exist because the majority of people are treacherous to non-human animals in general and with parrots it's so hard to breed them they go to extraordinary lengths to try. Obvious fact is they, especially the larger birds which are the hardest to breed, are not meant to be bred in captivity. Duh.
It doesn't matter if a breeder has forty pair or four hundred pair, it's a parrot mill if the dynamic above is in place and knowledgeable sources I found when researching my book said to a one they are all parrot mills without question.
Here are the links to "Parrots in Peril" the expose' on Martha Scudder, a breeder with 800 parrots. She kept them in a concentration camp like situation for decades and she still does. Even after a Sunday cover story in the Tacoma News Tribune (she was in that county) she wasn't shut down. There were city council hearings you can't imagine. The anti legislation faction did what they did at the hearing last month in San Fran only it was worse in Tacoma. Way worse.
This was the lead story and there were several sidebars I wrote as well. All told it was a 10,000 word expose! Took up the entire first section of the sunday paper. The only one I found online at the paper's site was the lead. So I'm attaching the one on factory farming of parrots as a PDF. And any other elements I find that was part of this big expose'. Took 7 months to do.