Instructions
Navigate to the checkpoint at the wide river crossing with the piranha after rescuing the woman from her parachute harness. She will point you in the correct direction so you can rescue her husband, Rodrigo.
Turn around at the piranha crossing and head southeast to a little inlet near the pond you crossed previously. Crouch here and watch for movement in the tall grass. Occasionally, a capybara will walk to the water to swim or take a drink. Carefully aim and take a shot, because capybara run very quickly when shot at. Not being detected is key to bagging one.
Pick up the capybara, then return to the river crossing. Select it in your inventory, then throw it in the water to keep the piranha busy while you cross.