We have had bluebirds nesting on our property for about 10 years here in west central Louisiana. They typically lay the first egg around the end of February/first part of March and continue on to raise 3 clutches of 4-5 eggs through the blistering heat at the end of July/mid August. We have 5 boxes on our 1-acre property and have had bluebirds nest in all of them at one time or another, though the birds do tend to favor a couple of the boxes over the others. Per usual, the first egg was laid 03/02/17, one egg each day after that until the 5th was laid on 03/06/17. Nothing unusual about their behavior. I check all the boxes each day in the early afternoon. Up until Friday afternoon 03/10/17 everything was progressing along and nothing appeared unusual...had seen the parents in and out of the nest each day. Yesterday, Saturday, I made my check and my first impression was oh, no, all the eggs are gone! Then I looked closer and saw that another thrown-together looking bluebird nest had been built on top of the nest with the 5 eggs in it. We have never seen that happen. Today, everything looked the same at first glance...no egg in the "new" nest. I looked underneath at the eggs in the primary nest...and there are only 4, not 5...nothing looks disturbed AT ALL. I will continue to observe. Just when I think I have the birds' habits figured out...something unusual happens...never gets boring! If anyone has any input on this, I would love to hear it.