•Two of the eggs mysteriously disappeared. These were probably carried off by the adults and dumped. Robin parents probably don't like infertile eggs to be trampled by the chicks after the eggs get a bit rotten. ( Remember Templeton in Charlotte's Web?)

•Two of the eggs never hatched at all. When all the robins had gone, Wayne found them embedded in the dried mud at the bottom of the nest! He also saw that the very bottom of the nest wasn't actually closed or solid. Perhaps Mom Robin just couldn't find enough mud, or she is still learning to be a good nest builder.