Using both latest spigot and then later latest bukkit build. Posted here as well: https://bukkit.atlassian.net/browse/BUKKIT-4487 What I wrote is also true for latest spigot builds. This was using b1017, b1009, and b1006. EDIT: last paragraph I meant mobs spawned in with 1.6.1 vanilla will despawn using bukkit or spigot. However, tamed wolves seem less affected and require more chunk unload/load to finally despawn...however they will despawn eventually. Their progeny, haha, however will persist if bred using bukkit or spigot.