Rabbits thump for a few reasons ... Usually fear or anger.
They might hear a''scary noise!''- And thump (sometimes several times.)
They might be scared of your appearance - especially if you wear clothes that it is not used to. (A few of our rabbits will thump when I wear a large black coat)
They might be annoyed at some behaviour of yours - - perhaps you reached into their cage (its their house!) Or you grabbed them unexpectedly or some such thing.
And sometimes there seems to be no real reason at all - one rabbit spent a fairly long evening sitting on my chest and would * thump * on my stomache about every 2 or 3 minutes. Never could figure out a reason ...
