As in our human kingdom, sibling rivalry is quite apparent inside a birdhouse. Primarily, rivalry is about food. Nestlings jostle for position. Getting closest to the door, and reaching highest with gaping mouth, seems to be the alpha pose. I truly do not know what cues the parents use to determine whom to feed next, but they obviously have it figured out. Rivalry, or not, everyone eats.
I remember having a furnace replaced. I had a small computer screen connected to the bird camera’s recording device in the area where the technician was working. The tech couldn’t help himself. He was caught-up in the world of the Chickadee nestlings; remarking on how taken he was with the fact that the parents made sure to feed each and every one.
Occasionally, rivalry takes a different shape — who gets to look out the door and see what’s going on outside. Every once in a while, pushing and shoving leads to an “oops moment” … an accidental fledge. Such is the case with the Chickadee siblings in the video. (FYI — the nestlings were old enough to fledge. I expect all went well in the world outside.)