This is a pretty simple quest, there are two groups of three Barnos, one in AREA 2 and another in AREA 9. These flying pests are most easily slain with ranged weapons, but if you provoke them, they’re usually willing enough to come within melee range for easier slaying. Just avoid any large monsters - the Bazelgeuse and Azure Rathalos both like to travel around - and you should be fine.