For the more natury rangers/druids and pcs out there, (although non rangers/druids would have a bit more trouble), would it be possible to add physical nests in the areas where ravens, stirge, howls, and falcons lives to harvest? It would make more sense. This way a ranger or druid would not have to kill the birds to get the feathers.
They could range for about the same as the bee nest/hive and gum arabic trees gets for the harvest.