On Monday the two red-tailed hawks starting sitting on the nest full time. The male and female take turns on the nest.
Gary and Diane noticed on Sat March 26, 2011 that the female was sitting for a hour and a half the flew off, on Sunday March 27, 2011 same thing. By Monday afternoon they made sure the nest was occupied full time.
So 35 days we should see female dipping to feed a eyas. End of April or first week of May.