I started soloing these guys at level 62. I am a solo Mage and had approximately 95 AA's at the time. Don't think I could have solo'd them any lower because they hit hard and are big mana burners. Their respawn time is 19-20 minutes. They have a very small aggro range. Also, they not run when below 20%. This won't help non-pet types much, but here is how I do it.
When I enter I go close to center and have my pet guard ( being careful not to get close enough to draw aggro ). I then move myself to the burning bazier to left of entrance. This puts me far enough away from pet to avoid the Silence AE they cast. I then have him attack the one on the right of entrance. They will hit him with the AE but as I stated, it will not reach me. I use air type pet, Ward of Xegony.
Once pet has the aggro I cast Malosinia to weaken the mob. Always watching pet HP's I then put the two Mage DoT's on them ( Wrath of the Elements and Elemental Maelstrom ). From that point on I just heal pet as necessary and recast the two DoT's as they run out. When Mob just below 20 percent I cast my best DD, Firebolt of Tallon, and the fight is over.
I then do same to the one on the left, then the center one. This lowers chance of aggro as they repop because they will be on opposite sides of room since the center one will pop last.
They conned DB to me at 62 and still do at 63. Also, from time to time a Small Blood Raven will pop ( LB to me ) and he WILL run at 20%.
Have killed many many of them. Loot so far has been " Blood Raven Beak ", " Blood Raven Parts ", and Ethereal Parchments.
Tried soloing these punks several times but got stymied since they run real fast, hit me 400+ *and* silenced me for too long. Couldn't cast anything so couldn't backup my pet when he was getting keeping the mob busy. By the time I got my voice back I couldn't figure out whether to cast DD or heal since my pet was almost past half hp. And that was just the single pull on the left side of the entryway; I'd hate to see what happens if I pull the two on the right.
Just so you solo folks know. These guys seem to still run/fly REALLY fast even when snared. I have never seen any mob move that fast when snared before.
Just got through killing in this zone. We killed alot of these birds and not once did they con even or lower to me... only yellow. So their lvl's can fluctuate but more often than not they're gonna be higher than 57. Also... if you get down the ramp some when these are pulled you won't get hit with the silence spell. That ae sucks... puller pulled two and it casted the silence spell... none of are healers could cast and do to these being yellow to me I couldnt mezz. Needless to say... tank died quick along with 2 others. Careful for the silence.