I would not despair yet. Often they don't hang around until she starts brooding. I assume there are no eggs yet? Just be patient. They know where the box is and more than likely will be back. Blues will often start more than one nest, so if there are other nest boxes nearby they could have chosen another one. But I'm betting they'll be back when she's ready to start laying eggs. Please remember to put up the sparrow spooker after the first egg is laid to protect them from HOSP. Once they have young to feed, you will see them all the time.

I agree with Kendra, same thing happened to me this year when I put my box up. I swear they were teasing me, as they would come and go, come and go. There were many days I didn't see them at all. Now that the Mother has layed her eggs I see her peeking out frequently throughout every day!

Thanks for the encouragement. The nest is ready for eggs, so I will keep checking before I put up the Sparrow Spooker. I read fishing line is a good deterrent. Any experience with that for keeping HOSP away? Thanks again!

I have used fishing line on all three of my boxes when i saw a couple of HOSP hanging around one of them. It does seem to deter them, but I put up a spooker on the one that has the eggs.