I was looking at that earlier and wondering the same.

Momma won’t hunt again herself until the babies have left the nest. Mr Owl is in charge of hunting for the whole family, and he will stash stuff nearby so they have meals as needed. Great Horned Owls can take some pretty big animals, and these little ones are pretty small yet, with the younger one still being so downy, so momma probably needs to cut up their meals for them yet.