Egg no. 4 happened sometime today. Four eggs is the normal size for a screech owl clutch (well, a mean of something like 3.75 is, if memory serves, what Gehlbach came-up with), so this is probably the last of the eggs. Now, Mme. Owl settles into relentless incubation for the next 30 days, and then continues that task for some weeks afterward as she broods the owlets.
It must be mighty boring for a born huntress, but she knows what needs to be done, and, of course, so does her mate, who'll be supplying almost 100% of the family's food for about the next seven weeks.