By Lisa R. (Sisugirl) on Sunday, June 10, 2012 - 11:11 am:
Getting to this one very late, but in case anyone visits this page... Building on what Mary and Eugenia already said... Notice how the eggs look like stones... alright, not the stones in the immediate vicinity, but if they were just on a plain surface taken by themselves, they look like stones. This species may have evolved to laying eggs on the ground because nesting sites up high are often harder to come by, whereas potential nesting sites on the ground would be more plentiful. To compensate for the increased risk of predation, they evolved the trickery behavior and eggs that look like just another pile of rocks.