Ross's x barnacle goose hybrid at Rockcliffe Marsh, Cumbria

Today I came across this remarkable looking hybrid goose on Rockcliffe Marsh on the English Solway, with 500 barnacle geese. It's similar in size and structure to barnacle goose but it has pink legs and bill, with a dark back and flanks and my initial impression was that the most likely parentage was either blue phase lesser snow goose x barnacle or Ross's goose x barnacle. My problem with the latter was that the dark flanks seem to indicate that one of the parents must be a blue phase bird, but blue phase Ross's goose is extremely rare to the extent that some authorities consider that they only exist because they are themselves likely Ross's x blue phase lesser snow goose hybrids.  Only 1 in 10,000 Ross's geese are blue.

However, having discussed the bird with @BirdHybrids my concerns about the dark flanks and back seem to be unfounded. They have commented "Ross's x barnacle hybrids typically (not always) show dark flanks. Presumably the genes for dark flanks are carried by all Ross's geese and are just not normally expressed in pure [white] birds - hybrids often show characters that aren't present on either parent.". Furthermore, Ross's x barnacle hybrids are often slightly larger than either Ross's or barnacle, as appears to be the case with this bird. This in itself is interesting and leads to further questions. For example, why would all Ross's geese carry the genes for dark flanks when blue Ross's geese are virtually unknown and may only be hybrids themselves?

It also begs the question, is this bird the result of a wild pairing or was one or both parents feral or escapes from a collection? The bird is unringed and with huge flocks of wild geese, around 15,000 across the wider marsh, but the barnacles wintering on Solway breed in Svalbard whereas Ross's goose and lesser snow goose are from North America. However there was also a North American vagrant Canada goose with the flock (Todd's).

It's not unknown for escaped geese to join up with wild flocks and often accompany them back to their breeding grounds, so perhaps at some point an escaped or feral Ross's goose has paired up with a wild barnacle? Personally I prefer to believe that both parents were wild, but we'll never know for sure. Whatever it's parentage and origin, it's a great looking bird and one which I was delighted to see. For further reading on blue Ross's goose from an American birder, I recommend this blog post (opens in a new window).

A very similar looking bird was photographed in Norfolk in 2009 and this bird or one very like it has been seen in the Caerlaverock area for several years.