Sorry to take so long to getting back to you good followers but, I have been trying to get confirmation. Many keen observers are always helpful. Here is what I’ve seen and believe is happening.
Yesterday, Sunday, the few hours that I spent at “the rock,” the female was in the eyrie and out of sight. The tiercel returned to “the rock” with prey. He went into one of his larders. The female, hearing his chupping on arrival, peeked over the edge of the nest site, thinking he would probably bring it to her. When he did not, she returned to brooding, not being off the eggs more than 30 seconds.
The tiercel then perched high above the eyrie on the skyline. You could see his stomach soiled with reddish brown dust from the nest. Most likely, he had previously been sitting on the eggs. I had to leave before I saw any incubation exchange. Today, I think that I will. So, I believe, that would make Sunday, March 3, 2013, the first day of incubation.
Happy trails, Bob