In case you're wondering, a clutch is the term for a group of eggs. (For those of you who enjoyed the analogy questions on the verbal section of the SATs... Clutch is to eggs as litter is to puppies.) Robins typically lay four eggs before they begin the incubation process. Our robin laid egg #4 today, so, by my calculations, we now have a full clutch!
According to my sources, the mother robin is supposed to start incubating the eggs once the clutch is complete. However, Mrs. Robin has been conspicuously absent from the nest tonight. There could be any number of perfectly good reasons for her absence. Perhaps she decided to spend one last evening gathering worms to fortify herself for the incubation process. Or maybe Mrs. Robin is an over-achiever, and she's planning to lay a fifth egg (although this seems somewhat unlikely, given that the nest is already pretty crowded with four eggs). I don't want to accuse our dear robin of being an unfit mother, so I will give her the benefit of the doubt for now.
In other news, Bill just finished installing a webcam (or, as we like to call it, a "robincam") so that we can monitor the nest remotely. I think Mrs. Robin will appreciate this development, because she doesn't seem to like it when we come near the nest. As I'm sitting here typing, I just saw (via the robincam) that Mrs. Robin has returned to the nest and started incubating. I'm glad that I gave her the benefit of the doubt, because it appears that she is indeed a very caring and devoted mother.