My parents have hung a wren house in their yard for as long as I can remember.  Every year, a little male comes and builds a nest.  Then he sings and sings for a mate.  Sometimes a female will come to lay eggs and raise a brood.  Other times, the nest will be abandoned for my father to clean out at the end of the summer.  This year, a pair has moved in, and while babies have not shown their beaks, there are signs that little ones should soon appear.