Great Blue Heron Chicks: Sounds of begging and rivalry
First the kids are playing and watching. At 0:30 they start their begging sounds and soon after mom arrives. Did they see her or did she hear them. The begging started abruptly so I suspect they saw her coming. They do their feeding thing (beak biting and pulling mom's head down) until 2:40. At this time, mom appears to have regurgitated a large piece of fish, hold it in her mouth and then deposits it on the floor of their nest. She tires of all the noise, so she sneaks off to the right, and departs.
In the background are two not so small chicks from the other nest - on top right and one behind the nest. The upper chick took her first leap (that I've seen) from one limb to another. Usually she hops from one limb to another using her wings to maintain balance. I suspect this is the last step before full flight.
Some photos of the Great Blue Heron 6 week old chicks
Green Heron Series - I've found a green heron nest under the great blue heron nest. The male and female have built a nest and she has produced 1 egg. Here are some photos of the mom, dad and nest
Mom in assertive mode (feathers erect)