Robin chicks politely open wide and wait for the food to be brought.
American Robin
On the other extreme, Anhinga chicks shove their heads deep into the parent's gullet searching for food. This went on for several minutes! If you look at the first image in last week's blog, you'll see in the center the mangrove that this chick was perched in. I suspect it fledged that day or the next.
Anhinga feeding