This was sent to me from a former colleague, a keen birder, an item on the home page of the West Midlands Ringing Group.
The quoted test as follows: "Whilst on car park island @LaneMarsh we noticed an Oystercatcher was sitting on 3 eggs, one being a strange one. Today J.Hunt took video footage of a Mallard sharing the brooding of eggs, has anyone else seen this behaviour? Check below for nest photo "
If you look to the right of the home page, and follow their twitter view (accessible to all, on twitter or not), and one of the postings shows a video of said mallard.....
Unknown said:The infamous Cuckoo Mallard, perhaps???
LOL
Or even cuckoo oyster catcher!