I think they’re on eggs.
On Thursday I saw them bringing the top nest material into the bird box – bits of soft rabbit fur and feathers. On Friday, I didn’t really see any activity. Saturday, though, one stayed in the bird box while the other two stood watch and brought seeds to the one inside.
That got me looking through my photos for timing of things last year. Here was the one and only time I checked the nest to try and get an idea of the timing of the behavior I saw. Obviously they had recently hatched. That gave me a good timeline for their nesting behavior.
That was on May 15, 2011. Working backwards based on the 12 days of incubation according to Peterson’s Western Birds’ Nests, would mean the first week of April the eggs were laid. If they are laying eggs this week, which I strongly suspect they are, that’s two weeks earlier.
Also, last year I managed to catch the last of the fledgelings just coming out of the bird box for the first time on June 14, 2011. So, we’ll have a month and a half to wait to see that again.