Yes they can be killed. I want to thank Blizzard yet again for making it possible for trolls to ruin bet battles.

Ya, I farmed that...ALL 2000...what a pain. I yelled out in the area and invited a few friends and guild members to get them while they can! A few weeks later I went there to finish out the quests to get my mounts and someone had opened one and there was a bunch...oh well, live and learn!