wild scrapy chickens/ducks

I am in the process of moving to a new property where I am going to have a large garden space they merges into a large natural/food forest the whole area will eventually be fenced in the with osage orange living fence. I want to introduce some kind of poltry that I can mostly let free roam the fenced in area as pest control.  I have no interest in eating them or using their eggs for food so I was wondering if there are any chicken or duck varieties that are well suited for this type of living with me being involved in they're lives as little as possible?

If you are really looking to go "hands-off", there's Guinea Fowl.  

In my limited experience;

Pros
Great watch/alarm bird
Extremely self sufficient
Eat pests, tend to leave your vegetables alone
Don't dig holes like chickens

Cons
Great watch/alarm bird (the noise is very annoying to some)
Extremely self sufficient (tough to catch/control)

I second the choice on guinea fowl and find a way easy way to get em in coop at night, like a special treat.  I heard millet only given at dusk is a way to coop em.  Predation is always a problem.  If chickens, you can an automatic door.  

With guinea fowls if they go un-cooped will they roost in trees? In the food forest area there is a number of large trees that they could roost in if that is some thing they will do.

Yes, they will find their own place to roost.  I had some that found my house and began roosting on top of my chicken run, which is an A-Frame about 12 feet tall.  They can fly better than a domesticated chicken, so are tough to contain.

I have some very large oaks that may do well as roosts for them. I have basically no experience with have poltry of any kind so guinea fowl sound right up my alley. Now I just need to track down a good source for them.