Tips & Hints to Deter Hawks

I am slowly wading through the many awesome threads on BYC for all things chickeny. If there is an appropriate thread please refer me! Appreciated.

I am interested in protecting my growing number of various flocks from hawks. I would like in the near future, on a rotational basis, to allow them to roam over 2 well fenced paddocks covering a hectare. One has less tree coverage so I currently lock it off. Only the one mature flock has a mature rooster and even he couldn't keep up with the distance the young ones boldly went (hence locking off the second paddock). I really do want my chickens to enjoy time out of their pens and "free range" before they go into the pot.
Our soil is not so great for new tree seedlings so it will take me a few years to develop more tree cover that the cows and donkeys do not eat and the lovely trees we do have loose leaves in the cooler months. Netting is not a practical option (costly and too big an area), I would really like to avoid tractors. So I accept there may be the odd loss but wonder if there are a few other tricks and tips old timers have e.g. scare crows or fluttering string lines that do not look hideous so I can maintain family harmony. (find & insert juggling emoticon here).
Gracias

Lets start with raptor species that operate in your area. I think it may also need to include eagles and fast running falcons.

You are correct with your start point, but I really have no idea, when I ask I am given a Guarani name or a shrug! Guarani is not easily translated into written words.
I can't see the hawks up close they generally fly very high in circles. I've not seen one sitting in a tree nearby watching, and we have tried to keep a look out. It seems they are shy around people.

You have several species that look similar to those in North American. Some look to be variations on the Coopers Hawk and one looks like a melanistic Red-shouldered Hawk. You may have to speak with the local poultry keepers for more insight, especially those that keep game fowl as they have vested in their birds and likely rear them free-range.

Are you in lowland, upland, forested, savanah area?

We're in lowland with a large hilly area in the distance, most forests around here are being converted to cash crops. People either have a few chickens running around in the yard under their shade trees or in small pens under trees or large commercial sheds. I haven't yet found anyone who can/does them roam on pasture land, but I have only been here a year and it does take time to find folks! Tree coverage does seem to be a common theme here with non-commercial chicken keepers (but then it gets very hot so houses need shade!!).