New Challenge

It often happens, when I take Rainey out, that we (ok, mostly she) find several deer. It also often happens, that we stand staring at the deer, and the deer stands staring at us. This can go on for quite awhile. Eventually, the deer invariably begins raising and lowering one leg, and then the other, in a sort of stamping motion. Very slowly, though.

So...I've been wondering...why?

Perhaps the deer are seeing if we will react to its motions? Is the deer trying to find out if we see it? And/or find out if we intend to do anything other than stare at it?