sentences:  Around 20 days of age, the chicks generally start standing, which becomes the main position over the course of the next 40 days.The whitish down continues until around 25 days of age, at which point it is gradually replaced by dark contour feathers that eclipse the down and the birds attain a general piebald appearance.After hatching, 80% of food items and 90% of food biomass is captured and brought to the nest by the adult male.