David is absolutely correct – clean out box now. They usually want to build a new nest & start fresh. P.S. Many site also recommend a very light bleach solution when washing out the box and then rinse it very well. I always do this, as one time a nest of TRES (which all 5 perished) had mites in it when we cleaned out box after the babies died (probably from the mites). They were crawling all over us – UGH!! Doesn’t cost anything and leaves box disinfected for next nest. Just BE SURE to rinse it very well with clear water & Leave out in sun to dry good. P.S. Yeah, I know – out in the wild no one washes out their nesting site, but then again this is what we are trying to do is improve on nature, aren’t we?