The overall drop rate on these is a lot closer to 35% than 5%.  However, most nights when I'm doing this quest, I end up killing 10 or 15 animals before getting any drops.  Once or twice, and I'd think it was just bad luck, but this seems to be a consistent issue, which makes me think (not for the first time) that there's a secondary mechanism at work on quest-item droprates beyond a simple percentage chance per loot.

This will definitely not be one of the quests I do for money once I hit Exalted with Netherwing.  What a pain in the ass.