Not sure, yet - they may start spawning after server maintenance, if they haven't done so already.
BTW, Harbingers vs. Turkeys is almost as fun as Turkey vs. Turkey.
I once had a mass of 8 Turkeys fighting each other at the Lyceaum and it was total chaos - well, except for when Illwill didn't know what was going on and wandered too close, and died (and kept dying, trying to loot his corpse)