In the Thousand Needles, a set of quests leads you into the Roguefeather Den, which is filled with harpies. These quests include:
Test of Endurance
Stop the Screeching
Stolen Freewind Supplies
The problem with the Roguefeather Den is that layering appears to be broken inside this cave, leading to a massive number of players in a tiny area. This creates heavy competition for spawns, especially when trying to tag certain mobs for quest objectives. Both Grenka Bloodscreech and Screeching Windcaller have rarer spawns and these quests may take a long time because of the layering issues.
Lots of people.
Inside this cave, you can see other players attacking things, but not what they're attacking. In addition, you seem to get hit by the AoE silence effect of the harpies in other layers, but can't see anything in yours. This seems to indicate that the layers are only partially combined and there's some weird bug here.
There have been some weird layering bugs since the launch of WoW: Forever, with players complaining on Day 1 that zones feel too empty, but now players have been complaining that zones feel too full and they're having to compete for quest spawns. If you pick up these quests, you may wish to do them later or after the layer issues are fixed.
P.S. There's also a bug with the Test of Endurance quest. If your quest objective doesn't update after looting the claw, you'll have to relog to get it to trigger.
