The men have large bows made from forest hardwood, which they use to hunt for animals including tapirs, monkeys, deer, wild pigs and other small mammals.
They have also painted themselves with the red dye, urucum, commonly used by tribes in the Amazon. It is made from the seeds of a fruit similar to the horse chestnut. The seeds are ground into a paste to form the dye.
The body paint is most likely a show of aggression, possibly in response to the plane's first flyover.