On 3 December, I posted a shot of this bird in the same place, on our substation parapet, looking immaculately groomed. A fraction of a second later, it gave itself a good shake, allowing this last one before flying off. Looking at its rear end, is that grey mass poop, on its way to join the other marks, and for whatever reason, looking grey?
Thank you for your comments, stay safe and well, and good birding!
John