Just two weeks ago I came back from a 20 day trip in the peruvian amazon, beginning in the Andes cloud forest and ending in the flatland rainforest along the Madre de Dios river. The biodiversity is just amazing but the conditions for wildlife photography quite hard. You have to cope with changes from extreme highlights in the hole of the forest canopy with a bird sitting as a perfect silhouette, which forces you to compensate exposure or block the AE on a similar (hopefully) lighted object to absolute darkness when your subject is in the middle of the thick rainforest vegetation. There is no ISO to compensate (I was using up to ISO 2000 on a Canon 5D Mark II). Flash is often useless as it bounces from branches and leaves which are more close to you than the object. All that meant that every picture has to be "chased" which also gives you a lot of satisfaction and moreover, many pictured species are not present in the DT database! All in one a unforgettable experience..
Photo credits: Hans-Peter Egert.