The little one had lain motionless at the side of the nest for several minutes. We thought it had been killed. Then it stood up and walked back into the nest, jousted with the larger sibling a bit, then they stood side by side preening like nothing had ever happened. Elapsed time from the image with the invading chick to this one is about 6 minutes.

Our friend, Alan, later explained that this is called "Siblicide". A number of bird species have this behavior, wherein the eggs hatch a day or two apart. The first born gets the better deal on food. Basic purpose is to make sure the first one survives, especially in lean years, while the the second chick is basically a back-up if the first doesn't make it. What doesn't make sense is that this was a good water year. Many of the other nests had two, and at least one had 3 chicks. In all other cases, the chicks appeared to be of comparable size. So we don't know why this nest had the size disparity.

I had thought at the time that if this little one makes it, it will be one tough bird. Sadly, two weeks later we went out there to see an Egret hanging dead in tree branches below the lower nest. Presumably it was this little one.