Mourning Dove Headshake

So pigeons and doves are known to do something a little odd--after spying their food, instead of just snatching it up off the ground, they move their head right down close to the ground and quickly pause to apparently focus on the potential food one last time before they grab it.  This happens so fast that it is hard to notice, but if you watch closely, you can see it as a bit of a shudder in the head motion of these Mourning Doves on my patio this afternoon.