Brazilian tree climbers help scientists by collecting samples of fruit and branches and installing cameras on tree tops to film birds and monkeys. These tree climbers are very important in an area where scientists believe they know only about 30 per cent of the biodiversity. Jose Raimundo Ferreira, known as Zelao, says the job is "very risky" and that's why there are only a few people doing the job. Zelao has already undergone surgery four times on damaged ligaments but has no intention of slowing down. IMAGES AND SOUNDBITES