Like here:

The same is true for the rabbit's head.
So you might want to test this out to verify that it's working as you intend once you've got the thing "rigged".
The underlying issue is that each vertex is associated with exactly one bone, and there are no weights. Consequently, if the head is rotated, all the associated vertices are rotated along with it 1:1. So you might end up with neighbor polygons crossing over and things like that, that leads to flickering and other visual artifacts.
Edit: Worse even, the part of the neck that's connected to the back of the head will stick out if the rabbit looks down. Weighting would solve that, but there is none.
I know, it sucks, but you might have to work around this flaw in some way.
David just made a stump for the neck that's high enough so that the head never exposes the flat part on top, no matter how it's rotated.
It looks best if the connecting vertex is somewhere near the rotation pivot of the head bone.
