A couple of things. First, jungle fowl, live in .... jungles. Heavy cover, harder for raptors to attach using speed. Harder to spot the chickens.
Back in the 70's when game chickens were still allowed to be raised, people would "farm" young stags. Six to eight months old, too big to let run loose or they would kill each other, but they would place one stag per house out in the country. The stags tended to stay put, roost in trees, browse for its own food. If it survived it was a pretty healthy and pretty smart rooster in excellent shape flying up in the trees to roost. Owls would get some of them by flying up into the tree and climbing along the branch to get to the rooster. Possums, same thing.
Game fowl owners would also have a lot of "yard" birds living free range, usually fed once a day. Lots of free, no work chickens, usually young stags running around too, before they became old enough to be territorial and would start fighting. And meat birds of course. Good luck finding the eggs though and few of the yard birds would be useful for fighting as their lineage was unknown. Owls and possums were know to take out a half dozen chickens on a branch, killing them one at a time, the birds rarely being able to fly or see at night.
Chickens are prey species, like rodents, so they have large clutch sizes and reproduce several times a year, depending upon their numbers to provide for some of the chickens making it through the year to repopulate. The down side to trying to raise free range no coop birds is that they will draw more and more predators of all sorts.