Does that round big thing mean danger?

I made a bit too much noise, so mama blackbird looked quite terrified. But she had just taken a bath and looked wonderfully fluffy.
The first extra shows the head of the hatchling.
The second extra shows both hatchlings now completely filling the bottom of the nest. You can see more feathers, but also still pink skin.
Today both hatchlings pushed mama blackbird upwards. So much power in just one week!