The chicks have grown very big. Here is a photo of all four of them in the box, the floor of the box is 8 inches square:
And here's a side by side comparison, Mom on the left and a chick on the right:
One chick has been brave enough to venture out of the box, first flying to the camera platform and then flying to the top of the box:
His first attempt to return to the box ended in a fall, presumably 15 feet to the ground, his second attempt got him to the door, but he couldn't get in and ended up on the roof again.
We also got a few odd shots of Mom and one of the chicks on the camera platform, click on a picture to see the larger version: