shortage of rocks? really??

see the guy carrying the rock? They would go to great lengths to find just the right sized rocks from which to construct their little nests (is that what you call them?) Anyway, the odd thing I noticed is that adult Adelies seriously fight over rocks, no kidding! If you look at a pic below, you can see one adult that appears to be somewhat bloody, and yes he was. I saw more than one bird appearing fairly injured (at least to my eyes) after getting into a pecking war over some rocks. weird.