On 3/26 - http://www.pbase.com/ed_k/image/41262003 - it was nest building. A little over a week later, it's five eggs. The nest monitor - we have about 30-40 of these houses in the community with an active effort to grow the bluebird population; they keep data on nesting habits, etc. - called me & gave me the opportunity to snap this during a routine "opening" of the bird house. One of my few ever hand held shots. The egg & back of nest seem fairly good at 1/10 sec; the front is DOF (I think).