Three of the Cayuga eggs are an unusual green colour. Cayugas are famous for laying coal-black eggs, but usually only the first eggs of the season are coal-black, as the black colour is a 'paint' deposited by a gland in the duck's laying tract. With subsequent eggs the black colour gradually diminishes until the coating leaves just a faint grey overlay. The egg underneath can be green or white according to the Cayuga standard. My old duck laid white, and most of the other Cayuga eggs I received in this batch are also white, so the green ones are a bit of a novelty. I will try to keep track of any ducklings from the green eggs, as these were obviously laid by a different duck to the others, and if they are of good type this might be an interesting trait to breed for.