Smew Mergellus albellus x Hooded Merganser Lophodytes cucullatus hybrid
This hybrid is sometimes recorded in the wild (whether or not the pairing that produced the hybrid occured in the wild) but I've only seen them in a wildfowl collection.
The owner of the collection where the following birds were photographed confirmed that they were acquired from another collection, hence their appearance despite no Smew having been present previously. Two similar birds were present initially, subseqently reducing to one - I am not 100% sure if both birds appear in the photos below. Initially both birds had grey flanks with virtually no hint of orange. Over a number of year the flanks of the remaining bird became increasingly orange.
captive Smew x Hooded Merganser hybrid, Blakeney Quayside collection (Norfolk, UK), 11th April 2009
captive Smew x Hooded Merganser hybrid, Blakeney Quayside collection (Norfolk, UK), 26th April 2009
captive Smew x Hooded Merganser hybrid, Blakeney Quayside collection (Norfolk, UK), 16th May 2009
captive Smew x Hooded Merganser hybrid, Blakeney Quayside collection (Norfolk, UK), 9th January 2010
captive Smew x Hooded Merganser hybrid, Blakeney Quayside collection (Norfolk, UK), 13th February 2010
captive Smew x Hooded Merganser hybrid, Blakeney Quayside collection (Norfolk, UK), 4th December 2010
captive Smew x Hooded Merganser hybrid, Blakeney Quayside collection (Norfolk, UK), 12th February 2011
captive Smew x Hooded Merganser hybrid, Blakeney Quayside collection (Norfolk, UK), 15th October 2011
captive Smew x Hooded Merganser hybrid, Blakeney Quayside collection (Norfolk, UK), 25th September 2012
captive Smew x Hooded Merganser hybrid, Blakeney Quayside collection (Norfolk, UK), 1st December 2012
captive Smew x Hooded Merganser hybrid, Blakeney Quayside collection (Norfolk, UK), 19th January 2013
captive Smew x Hooded Merganser hybrid, Blakeney Quayside collection (Norfolk, UK), 9th November 2013
For comparison, here are photos of the parent species.
captive Smew, St James's Park (London, UK), 16th March 2018 and escaped (?) Hooded Merganser, Radipole (Dorset, UK), 2nd May 2009
For more photos of these species follow the links below: