Everytime I see this, my brain focuses on the bone cupping the bottom of the egg, and it hurts me. I don't know what actually happens, but I know it hurts. Poor little birdy. What fruit in what garden did you eat, little bird?
And yet bbc had the audacity to gloss over this and claim the male does the hard work. While paternal care is normal for birds related to the ostrich, the male kiwi, has it the easiest.