I had something similar happen last season. My mama was incubating 5 eggs, and one day I found an egg on the ground, under the pole, no sign of trauma or anything. She continued to incubate other eggs & they fledged. I came to the conclusion it was removed by them for some reason, probably not viable, but like Gin says, we never know for sure. Good luck on the other eggs. I have no full nest yet – my pair are strange in that they want to build 2 or 3 nests first and finally decide which one to use later.
P.S. Mullybirds – it is highly recommended that the sparrow spooker NOT be put on before the first egg is laid. Looks like your pair accepted this early, but this is not the usual thing to do. We wait until they are committed with the 1st egg, and then put up the spooker. Also, the HOSP can get really accustomed to the spooker if it is part of the box right from the start. But looks like you have done great for the first attempt at bluebirding. Good luck!! By the way, where do you live – must be in a warmer state to have eggs being incubated for several days already.
