Observing Amazons in their Natural Ranges is possible as more and more Central and South America countries are providing ECO Tours as specific Government areas are set aside for such viewing.
There has been several field studies supported by grants for those individuals completing their Masters and Doctorate degrees. Organizations like the Amazona Society, England (not sure they are still active) have provided limited financial support in the past. The majority of those Studies had been with the Blue Fronted Amazons.
There are several organizations that have, are beginning, or now are reporting under the CITES International. So, that will be a good source. Historical Books regarding the Amazon Species is also a wonderful source and near every one is now on the Web. As with any web searches it is important to be aware of Junk Science and Arm Chair Research.
It is important to remember that in the recent past, the use of rainforest in place of jungles has become problematic as rainforestes are areas that have fairly long periods of freezing temperatures. This all came about as a small group of individuals came to believe that by referring to jungles as rainforestes that people would become less willing to allow them to be cut down and converted into farm land. There are sad stories of Park Rangers finding bird cages left open as individuals in NorthWestern North America or from other areas would drive to the real rainforest to release their Parrots.