They seem so helpless. I waited but saw no sign of their mother. They do not need to be rescued. The mother would not return as long as you remained near the nest. Just replace the top of the nest you uncovered and leave.
Cottontail rabbits leave their young for hours while feeding themselves.
Typically, they feed their young only three times per day. If you want to be certain the mother has returned, you can place two pieces of thread in an X over the nest and check the nest the following day. If the thread has been moved, mom has returned. Q. A baby bird has fallen out of its nest in a tree in my backyard. I am afraid something might happen to it if I leave it on the ground.