Sunday, 23 February 2014

(Swan Goose x Greylag Goose) x Canada Goose

probable (domestic Swan Goose x Greylag Goose) x Canada Goose trigen, Ythan Estuary (Aberdeenshire, UK), 18th March 2014 - copyright Dave Appleton
(photo ID: 1555)


Many domestic geese contain a mix of Swan Goose and Greylag Goose genes and when such mixed-species domestic geese hybridise with Canada Geese the offspring may resemble either Swan Goose x Canada Goose hybrids or Greylag Goose x Canada Goose hybrids - sometimes both in a single brood. Consequently it is often impossible to tell whether the domestic goose parent of a domestic goose x Canada Goose hybrid was a mixed-species domestic goose or a single species.  For all of the birds on this page there is some reason to think that the domestic goose parent may have had both Swan Goose and Greylag Goose ancestry.

(See also: Swan Goose x Canada Goose, domestic Greylag Goose x Canada Goose, wild-type Greylag Goose x Canada Goose)


This bird above showed a predominantly black bill suggesting Swan Goose involvement, but a small amount of pink on the bill, suggesting a different Anser species was also involved (Swan Geese may show a little orange on the bill so perhaps not definitely so).  Some more photos of it follow:








probable (domestic Swan Goose x Greylag Goose) x Canada Goose trigen, Ythan Estuary (Aberdeenshire, UK), 18th March 2014 - copyright Dave Appleton
(photo IDs: 1556-1563)


The Thetford birds below were a group of eight, accompanied by a domestic goose and a Canada Goose.  The domestic goose closely resembled domestic Greylag Goose but showed some features suggesting Swan Goose ancestry, including a dark nail (see the Swan Goose x Greylag Goose page).  The hybrids varied in appearance, some looking much like typical Greylag Goose x Canada Goose hybrids.  Others were longer-necked, as is often the case with Swan Goose x Canada Goose hybrids.  Curiously some of these birds showed darker body plumage (with contrasting paler bellies) than is typical of Greylag Goose x Canada Goose hybrids, or Swan Goose x Canada Goose hybrids - not sure what significance this has, if any, but I don't see any reason to invoke any of the species that might be expected to show this (White-fronted Goose sp. hybrids and Snow Goose hybrids can show such dark plumage, but no evidence of their involvement here).











probable (domestic Swan Goose x Greylag Goose) x Canada Goose trigens (with apparent domestic Swan Goose x Greylag Goose hybrid and Canada Goose), Thetford (Norfolk, UK), 9th February 2013 - copyright Dave Appleton (photo IDs: 0029-0039)


There were still seven birds here 3.5 years later, though I can't be sure they were seven of the original eight of course but they were associating closely with one another in exactly the same spot so my guess is they were the same or younger siblings.







probable (domestic Swan Goose x Greylag Goose) x Canada Goose trigens (with apparent domestic Swan Goose x Greylag Goose hybrid and Canada Goose), Thetford (Norfolk, UK), 19th November 2016 - copyright Dave Appleton (photo IDs: 2808-2814)


The following four birds were together, so I assumed they were likely to be siblings.  The two birds in the first two photos could have been domestic Greylag Goose x Canada Goose hybrids but the two in the third photo both had black bills, suggesting Swan Goose ancestry.  Note that one of each showed white flecking on the neck, and unlike many domestic Swan Goose x Canada Goose hybrids, all showed ochre-yellow legs, not orange.



probable (domestic Swan Goose x Greylag Goose) x Canada Goose trigens (with Greylag Geese), Drift Reservoir (Cornwall, UK), 1st October 2005 - copyright Dave Appleton 
(photo IDs: 0049-0051)


The following photos show birds from a small group.  The bird(s) with an all-dark bill, sloping head/bill profile and bright orange legs looks like typical Swan Goose x Canada Goose hybrids while the others look more like typical Greylag Goose x Canada Goose hybrids.  The fact that they were together doesn't prove they were related but if they were siblings then the odds are they were all offspring of a domestic Swan Goose x Greylag Goose hybrid.




probable (domestic Swan Goose x Greylag Goose) x Canada Goose trigens, Kammerslusen (Denmark), May 2006 - copyright Lars Michael Nielson 
(photo IDs: 0911-0914)


The structure of this bird suggests Swan Goose involvement and the white plumage clearly indicates domestic goose parentage, but given the amount of colour on the bill I think the domestic parent was unlikely to have been pure Swan Goose.

probable (domestic Swan Goose x Greylag Goose) x Canada Goose trigen (with Canada Goose), Danvers (Massachusetts, USA), October 2013 - copyright Davey Walters 
(photo ID: 1912)


I wouldn't argue with Steve's commentary on the next bird:
Presumably Canada x Anser sp.; plumage-wise it looks like a fairly typical Canada x Greylag, but perhaps the head/bill shape suggests domestic Swan Goose parentage?  (Also apparent white on the forehead resembles some Barnacle Goose hybrids, but size and structure make this unlikely.)"
The white forehead patch does seem unusual for Canada Goose hybrids, at least those involving the larger feral forms of Canada Goose (such markings on smaller Cackling Geese are more frequent), but I don't see any case for an alternative at the moment.



possible (domestic Swan Goose x Greylag Goose) x Canada Goose trigen, Gorton Reservoir, Manchester (Greater Manchester, UK), June 2011 - copyright Steve Graby 
(photo IDs: 1978-1980)


Swan Goose Anser cygnoides 
Greylag Goose Anser anser 
Canada Goose Branta candensis

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