I was just about to start a thread about this!
Since I let my chickens live a natural 100 percent free range life they are really healthy, reproducing like crazy.. I have a population explosion now!
I have lost no birds for about a year since they live 'wild'. I had about 10 birds and now I have lost count.. but easily over 50... all ages and sexes.
When I kept the birds in the coop.. I had roosters fighting, hens attacking chicks, bad hatch rates, lots of fowl pox and other diseases. It seemed to go from one disease to the next with my flock.. and cost me a lot for medication. I got through so much feed too. The coop was big, well ventilated and dry.. I kept is clean and dusted for mites etc... it was hard work.
I lost many birds to predators when they were in the coop.. The chickens were trapped in the coop and run when a mongoose or dog would break in.. and they were easy to catch and kill with no chance to escape.
I was going to give up keeping them after several months of diseases and predator attacks, 2 costly coop rebuilds and the heartache of nursing sick birds which usually died.
One night I got home late after dark and the coop door had blown shut so the birds could not get inside.
I shone the torch around and spotted them high up in the mango trees.
Ever since that day they live 24 / 7 outside the coop.. and since then I have not had any disease with them.. only one cut its eye.. and that healed with no treatment. None of the roosters (must have about 10 now) are fighting.. the hens are all in perfect feather condition and there are big swarms of different sized chicks running about everywhere.
My feed bill has reduced to next to nothing.. they find most of their own food on my land.. which is a big fruit orchard. I have no coop, feeders or nestboxes to clean out... the chickens drink from the lake.. and I throw feed on the concrete area near the old coop. They nest in their own secret places.. usually under bushes.. sometimes up in the trees in old bird nest.. and even in old flowerpots.
They are really alert to predators.. doing all their natural alarm calls and behaviours.. and I have not lost a single one.. even a tiny chick!
There is plenty of cover for them..dense thorny bushes, log piles, and scrap wood and 'junk'. They have about 100 trees to choose to roost in.. but they always use the same one. The go right up into the top most branches. I am always surprised how very young chickck can scrabble and hop their way up.. I have seen them climbing vertical tree trunks.. grabbing hold of the rough bark with their feet.
Now I have so many of them.. I can afford to loose a few to a snake or mongoose.. and dogs have no chance to catch them now.
I am lucky to live in a hot climate... I would not do this in a place with ice and snow in the winter.
Now I am going to have to decided how to stop them breeding... have to go nest hunting this week!