Extreme violence and cannibalism is pretty common in commercial breeds or any animals intensively farmed for recent generations, it takes a good half dozen or so generations to breed out the negative traits once you buy the initial stock from such a place, but my turkeys are backyard-bred mongrels and I've also had violence issues among them. But, the issues remain in backyard keepers as with most hatcheries, as they're intensively caged and violent animals are bred on. Just giving them a free range environment doesn't magically make them nice and happy birds, they are still running a 'cage mentality' in their heads and will for generations to come. May help to think of them as violent prison inmates, if that's not too bizarre... They often can't cope in normal society and lack basic social skills and resort to extreme violence over the mildest causes, or for no reason at all. This is common with all intensively caged animals.
Ganging up and obsessive aggression are very, very strong traits in almost all turkeys I've seen, mine or others'. Once they start they get stuck into a killer mindset and can't stop.
The tiny babies at a few weeks old would get into epic battles and savage one another and be unable to stop. I'd separate them and they'd be right back at it, for hours and hours on end, instead of free ranging with their mother.
One turkey hen I had showed escalating violence towards another hen until she and her daughter smashed than hen to the point that she died a slow and painful death.
To give you an idea of the sheer amount of force they used, there was a stainless steel pot in there with them for water, and they dented that flat in one side, into a D shape instead of an O, if you're viewing the pot from above. That's enormous force, it was a thick quality stainless-steel pot, large enough to hold two roast chooks, about 7 inches deep.
Shouldn't have happened, I had them separated; but a nice old lady who thought she knew better (even after I explicitly explained to her the reasons for their separation, and the likely outcome or putting them together) put them together when I wasn't around, and that was that. It was kind of a good thing because she later put a tiny damaged bantam hen who's a family pet in with the turkey after she was smashed and separated again, and if the turkey hadn't been dying the bantam hen would have been killed by her. I'd also explicitly told her why that bantam hen had her own living quarters (her skeleton was broken and had weakly healed but remained a liability). Still rankles a little even though she had all the best intentions, there was nothing malicious in what she did. I don't blame her but I've had a gutful of people doing whatever they want behind my back with my animals, despite me telling them certain issues will occur if certain situations are brought about.
Anyway... Most turkeys I've had are extremely violent, it's due to people keeping and breeding violent turkeys, as it is with chickens who exhibit extreme violence. The cure is to either work to breed it out or cull them and buy a calmer lot and continue to cull excessively aggressive individuals with every generation until they stop being produced. I did that with my chooks, worked like a charm, no bullying, no killing, no cannibalism --- all of those are strongly heritable and abnormal traits --- but I've yet to do the same with my turkeys due to moving house and only retaining one. I'm going to start from scratch if this one looks like she'll be alright, but I doubt it, I may end up buying more in. Wild pigs broke into a cage and ate my best male and female while I was agisting them on another property, such a shame, I'd bred for Blackhead resistance to the point where they weren't affected, only to lose the pinnacles of that breeding program. Eh, at least now I know how very achievable it is.
They were also the least aggressive I'd managed to breed, I had no issues with either. Back to square one now.
Best wishes.
