After you investigate the flying creatures reported by the peddler, Lothaire wants you to visit the Hedgetree.
This quest is only available if you started the game in Gridania, you have completed the quest Migrant Marauders, and have reached level 13.
Starting the Quest
Talk to Lothaire in the Central Shroud to begin the quest.
Speak with Leonnie
Go southwest to the location marked on the map and minimap. Speak to Leonnie.
Speak with Armelle
Go north, then east, then south to the Mirror Planks dock. Talk to Armelle to complete the quest.
Next Main Scenario Quest
After completing the quest, talk to Armelle to accept the next quest: Salvaging the Scene.