On Tuesday morning ( Feb 7th.) when I went into my shed to feed my horses I found half an egg shell. To me it looked fresh, and had not been there the evening before. I am almost sure it is a blackbird's egg. Is it possible it is this year's egg? I live in Perthshire and we have had minus temps for a week. The only other possibility is that is is last year's but it was very clean and undamaged and where didi it come from?
If you can take a photo of it and post it in here, someone will be able to ID it for you. I found a couple in February last year that turned out to be from a collared dove. They mate at any time, so not unusual to see one of their eggs.
As to where it came from, this is anyone's guess. It could have been predated by a corvid and dropped.
See my photos on Flickr