Excellent. I'm looking forward to you adding more to it.
I read a lot of it thinking that it doesn't really help me in my backyard, then right at the end you brought it back in nicely. I'll pass the link along to my neighbor (who does keep a couple of chickens in his back yard) - although with 3 small children also sharing the back yard I'm not sure if he will be able to have the large areas you mention. Knowing him, I suspect he will start looking at getting a llama "for protection" (nothing to worry about here except cats).
Went back to Hawaii about 6 or 7 years ago -- Kauai to be exact. And to my surprise, the whole island was infested with chickens. I don't remember the chickens, on the previous visits many many years before. Where the heck did all these wild chickens come from? So, I asked some of the locals...
Apparently, a hurricane hit the island in the early 90's, and quite a few farm chickens got free. The farms decided it was just easier to purchase new chickens than to catch the ones that escaped. Many years later, the whole island is full of wild chickens...
Personally, I am totally surprised. I thought domesticated chickens would have just died if they are left in the wild.
Not in Australia. No - there are domestic cats that have gone feral, and even some of the domestic cats are only domestic in name only. Many areas of Australia have a permanent cat curfew - cats aren't allowed out of the house between dusk and dawn. Despite this there are a large number of cats out and about after dark.
When thinking of predators I forgot about foxes. Some bright person in the early days of Australian white settlement decided that it would be a good idea to bring some foxes over so he could still have his hunts. Of course with no natural predators the fox population exploded.