I've had turkeys, peacocks, geese, chickens and guinea fowl all sharing the same yard, 2 cages and 5 acre paddock before. Not for long but I didn't see any reason it could not be prolonged; if it's achievable even once it can be replicated. The reasons why it didn't last long are varied and detailed below.
But it can be done peacefully if you take a strong stance against those individuals inclined to violence, and by strong stance I mean cull or rehome. For the majority of the time it was peaceful but I culled some geese and ganders for violent attitudes and left those that could get along with turkeys, chooks etc. The violent fight-starters are in the minority but they make enough trouble to keep the whole flock stressed 24/7 and give the impression they're all just incorrigibly violent creatures, but they're not.
Here's my experience, anyway. How it went: Peacocks decided to abandon the place quickly (within two weeks) but there were no fights. Guineas, I abandoned early (as in, rehomed) due to them trying to eat turkey babies. They never reached adulthood on my place, so I have no advice on how to get them to get along with each other; mine did, but they were juveniles, and my issue was with them attacking turkey babies. Culling the violent trouble-starter seems to be the way to go in general though.
Eventually I also rehomed the remaining geese, because their family bond was too strong and the increasing depletion of their flock into our stomachs was making them more and more anxious. (We never culled in front of them, and were never violent or anything like that, but they couldn't cut it as livestock kept for meat because they missed each family member too much. So they suffered and stressed and I have rules against that because happy meat is healthy meat).
The geese did not break up chook fights, ever, though they did bully my chooks for the first little while. I ate the most violent ones, and the nicer ones learnt to get along with poultry. I lost some good ganders to them taking nighttime flights into poles, fences, etc. There was one huge showdown between my last gander (nasty bird, that one, hostile to humans) and my only adult tom turkey at the time, because the tom was rolling eggs out from under the geese and trying to sit on them to brood them. The tom won by a narrow margin. He had never been violent before or after that. Some tom turkeys have quite a lot of maternal instinct and take offense at seeing any female except turkey hens sitting on eggs. They think all eggs are turkey eggs.
For a while, my turkeys (from the first lot I got) were too violent, but again it was mainly due to one bully, in this case, a stupid chicken. There was one nasty rooster I named B*stard because he abused my hens and attacked my face. First rooster we culled. Hens refused to mate with him, that's how much the rest of the flock hated him. They would crouch, keep their tail down and just refuse to mate and he'd start ripping out all their feathers in anger.
He would wait until the turkeys were relaxing, lying down or with their backs turned, and attack them. Once they turned around he'd flee. But they would all chase and gang up, and turkeys can get stuck in killing mode, as you've probably seen with your toms. I trained them to stop when told with clapping, shouting, etc whenever they started making their angry noises, and if they didn't listen I'd chase them around kicking their tails or throwing very soft small objects --- never connecting with their bodies with either my foot or any real force with thrown objects. Soon they were more worried about me than chasing the rooster. This worked for the first lot, especially once I separated and culled the nasty rooster who kept starting it. The turkeys were destined to be eaten anyway, but I needed them to reach adulthood for that. The bad rooster nearly forced my hand there. My other roosters quickly learnt to not square up to a turkey, and that was all; peaceful from then on.
But this lot had come from someone who breeds toms who attack whenever your back is turned so the toms started doing this to humans and the females as adults were too scrappy, always looking for a fight, so I culled the lot and later bought in new turkeys from another place. These were much better but did include the male who fought with the gander, which was a once-off anyway. No issues once the geese were gone, though the new female did get violent on another turkey hen she disliked. But that hen had the rain-drowning issue, that inbred spasm that makes her neck twist back whenever she hears water drops. She had to be culled anyway. She was a nice girl though.
With the chooks, I steadily culled for the following faults: bringing excessive violence to a hierarchy dispute; drawing blood more than once; harassment or unwillingness to be peaceful; aversion to humans; aggression towards chicks; aggression towards ill or injured birds; males abusing females or being clumsy as a rule, not just because they were young/inexperienced; males who would not listen when a hen protested she wasn't wanting to mate; males who tried to mate with hens who were trying to lay on the nest; and of course, aggression or sexual attraction towards humans. This may sound like I culled the majority but it was in fact the minority, and the most severe faults among them arrived in the first generation with chooks I bought in and did not breed myself. The lesser faults cropped up occasionally for the next few generations and I culled for them, but the violence was almost 100% gone with the first generation.
This is partly due to freeranging, not breeding nasty birds, and feeding them a rich diet. Kelp is a complete multivitamin and mineral containing feed item you can supplement them with. It's just seaweed, but once their entire nutritional needs are being met, they can be overpopulated and not mind at all. (It's a large part of how I can run a 50:50 ratio of roosters to hens peacefully). Often the 'complete' feeds from the stores are survival rations rather than the full spectrum of everything they need, and this leads to them being aggressive and anxious because the solution to their dietary deficiency is to depopulate so they receive more nutrition. It triggers powerful instincts. It helps to not breed from commercial hatchery birds, which often have warped social instincts at best, and are often the most violent, cannibalistic, baby-killing chickens of all.
In a nutshell if you amp up their nutrition and kill/rehome those inclined to start fights nonstop, you will very soon have a peaceful combined flock. I can't speak for birds caged nonstop but I doubt you're doing that with so many species. What behaviors you allow are being reinforced every time they are successfully acted upon, and will become behavioral patterns that will be inherited by the offspring. It's fairly crucial to break the habit/pattern of violence. Often the only way to do that is to cull the violent ones. Whatever your choices, best wishes with it all.
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