Egg in front garden in Sheffield

Egg in front garden in Sheffield

Observation - Egg in front garden in Sheffield. Description: I found this egg deposited in my front flower bed. There is no sign of a nest, but the egg is fully intact. Can anyone suggest what bird has left it there and why at this time of year?

I found this egg deposited in my front flower bed. There is no sign of a nest, but the egg is fully intact. Can anyone suggest what bird has left it there and why at this time of year?