foreclosure?

so our robin stopped coming back and the eggs were gone (no idea what happened there).  the nest sat vacant for about three weeks.  then one day a new bird was in the nest and we can probably count on one hand the number of times we have seen it leave.  even when matt walks within a few feet of it going to and from work, it doesn't move.  we were even starting to wonder if it was alive.  we will see if any babies come.  love.