A robin has successfully raised 3 or 4 robins in a nest in my shed. Yesterday, the nest was empty so I presume the fledglings have left but both parents were still on the fence by the shed when I emerged and no sign of baby fledglings. The female parent has been in the same place more or less till the end of the day yesterday, often whistling and going in and out of the shed but still no sign of babies or male. Today, she is still outside on the fence, alone. I worry that something has happened to the babies and she is looking for them. Or could it be that she is planning to reuse the nest for her second clutch?