Friday 28 February 2014

Snow Goose x Canada Goose

 Snow Goose x Canada Goose hybrid, Sweden, 10th October 2006 - copyright Carl Gunnar Gustavsson
(photo ID: 1102)


At the time the next bird was first discussed its identity was not fully resolved, but I think with what we know now the ID seems pretty solid (though please comment if you disagree).  It lacks a grinning patch but Carl Gunnar informs us that accrording to Randler (Alula 2, 2001) this does not exclude the possibility of Snow Goose heritage; the bill colour is similar to that of Snow Goose but much darker.  It has pale tips to the tail feathers and pale tertial edges that point to Snow Goose and Carl Gunnar notes that the leg colour is similar to that of a Snow Goose x Barnacle Goose hybrid.







Snow Goose x Canada Goose hybrid, Sweden, 10th October 2006 - copyright Carl Gunnar Gustavsson
(photo IDs: 1096-1101)


The next bird is trickier.  Apparently appeared in four successive years and one local breeder was sure that it was Snow Goose x Barnacle Goose.  Indeed the neck did not seem so long as the Snow Goose x Canada Goose hybrid above, but the brownish plumage is certainly more reminiscient of a Canada Goose hybrid (or Cackling Goose) rather than a Barnacle Goose hybrid.  It does seem to have a hint of blue-grey in the wing-coverts, which could be attributed to Barnacle Goose heritage, but it's so Canada-coloured that the proposed identification of Snow Goose x Barnacle Goose feels uncomfortable.  It's identity is not certain therefore, but its similarity to other Snow Goose x Canada Goose hybrids is striking.  The wing-stretching in the photos below reveal a white leading edge to the wings.






possible Snow Goose x Canada Goose hybrid (or possibly Snow Goose x Barnacle Goose hybrid), Lomma, (Sweden), probably autumn 2002 - copyright Carl Gunnar Gustavsson
(photo IDs: 1088-1092)


The next photos show what is presumably the same bird, the year after the above photos were taken.  It's appearance is very similar, although by now it appeared a little bit whiter.



possible Snow Goose x Canada Goose hybrid (or possibly Snow Goose x Barnacle Goose hybrid), Lomma, (Sweden), 19th April 2003 - copyright Carl Gunnar Gustavsson
(photo ID: 1069)



possible Snow Goose x Canada Goose hybrid (or possibly Snow Goose x Barnacle Goose hybrid, with Barnacle Goose), Lomma, (Sweden), 26th April 2003 - copyright Carl Gunnar Gustavsson
(photo ID: 1070)




possible Snow Goose x Canada Goose hybrid (or possibly Snow Goose x Barnacle Goose hybrid, with Barnacle Goose), Lomma, (Sweden), 27th April 2003 - copyright Carl Gunnar Gustavsson
(photo IDs: 1071-1072)



possible Snow Goose x Canada Goose hybrid (or possibly Snow Goose x Barnacle Goose hybrid), Lomma, (Sweden), 28th April 2003 - copyright Carl Gunnar Gustavsson
(photo ID: 1068)


Presumably feral birds are responsible for this hybrid when it occurs in Europe but in North America it is a naturally-occurring hybrid involving wild birds.

Steve notes that the following bird dwarfed the nearby Cackling Geese.  The dark plumage suggests blue morph Snow Goose, but apparently pure blue Snow Geese are more unusual than hybrids in this location in winter.





Snow Goose x Canada Goose hybrid, Frederick, Weld County (Colorado, USA), December 2013 - copyright Steve Mlodinow
(photo IDs: 1118-1121)


Concurring with Carl Gunnar's observation above, Steve notes that the grin patch on this hybrid varies, with the next bird hardly showing it.  He points to the "blocky" head shape indicating Snow Goose parent rather than Ross's Goose.  To give an idea of how regularly this hybrid occurs in some places, this was about the 20th Steve had seen in NE Colorado during the winter.





Snow Goose x Canada Goose hybrid, La Salle, Weld County (Colorado, USA), 17th March 2013 - copyright Steve Mlodinow
(photo IDs: 1190-1193)


Steve points out that the very dark brown (almost purplish) body combined with blue Snow Goose like head pattern seems to be a fairly typical pattern for Snow Goose x Canada Goose hybrids, probably even when a white morph bird is the Snow Goose parent.  The wing coverts are paler as well, as one sees in blue Snow Goose.  Steve also notes that the next bird lacks pink on the legs and bill, unlike most Snow Goose x Canada Goose hybrids, but it has the more rounded head of a Snow Goose (vs. Canada Goose) and thicker bill.  Based on size and companions, the Canada Goose parent is a Lesser Canada Goose (form parvipes).




Snow Goose x Lesser Canada Goose (parvipes) hybrid (with Lesser Canada Geese), Loveland, Larimer County (Colorado, USA), 15th December 2012 - copyright Steve Mlodinow
(photo IDs: 1202-1203)


The next birds, with their big bulky body and bill, are larger than the accompanying Lesser Canada Geese (form parvipes).  They were two of six such hybrids at the site.


Snow Goose x Canada Goose hybrid (with Lesser Canada Geese), Poudre River Trail, Greeley, Weld County (Colorado, USA), 3rd February 2013 - copyright Steve Mlodinow
(photo ID: 1217)



Snow Goose x Canada Goose hybrid (with Lesser Canada Geese), Poudre River Trail, Greeley, Weld County (Colorado, USA), 3rd February 2013 - copyright Steve Mlodinow
(photo ID: 1220)


The next bird is not so typical in its appearance, showing a black neck ring and not being as dark as usual below.  But Steve points to its size (about the same length, but much bulkier, than the surrounding Lesser Canada Geese, form parvipes) and the large head as indicative of the ID.


Snow Goose x Lesser Canada Goose (parvipes) hybrid (with Lesser Canada Geese), Prospect Pond, Larimer County (Colorado, USA), January 2013 - copyright Steve Mlodinow
(photo ID: 1232)


Another hefty bird with large head and moderately large bill:





Snow Goose x Canada Goose hybrid (with Lesser Canada Geese parvipes and Cackling Geese), Severance, Weld County (Colorado, USA), 19th February 2014 - copyright Steve Mlodinow
(photo IDs: 1522-1525)


Steven draws attention to the next bird's size compared to the Lesser Canada Goose (parvipes) immediately to its left (well, slightly behind) and the behemoth moffitti behind that.

Snow Goose x Canada Goose hybrid (with Lesser Canada Geese parvipes and moffitti), Firestone Gravel Pits, Weld County (Colorado, USA), 22nd December 2014 - copyright Steve Mlodinow
(photo ID: 1732)


The next one is unusual, as Steve points out:
"This is a peculiar pattern for this cross, looking more like what I'd expect an F2 to look like, but I don't believe this cross is fertile, so we shouldn't see anything beyond F1.  In any case, the rounded big head eliminates some weirdo Canada Goose and the bill shape eliminates an oddly colored Snow Goose"

Snow Goose x Canada Goose hybrid (with Canada Geese parvipes and moffitti), Aurora Reservoir, ArapahoeCounty (Colorado, USA), 11th December 2014 - copyright Steve Mlodinow
(photo ID: 1731)


I've a feeling the next bird might be another example of Snow Goose x Canada Goose - but am I right in ruling out domestic Swan Goose x Canada Goose which was the photographer's suggestion?  It does look quite long-necked...


possible Snow Goose x Canada Goose hybrid, Stalybridge (Greater Manchester, UK), August 2010 - copyright Steve Graby
(photo ID: 1962)


Next up is a fly-over - over the moon no less!  Probably safest to keep the "possible" tag given the views but it looks right to me.



possible Snow Goose x Canada Goose hybrid, Montgomery (Pennsylvania, USA), on or before 13th March 2015 - copyright Scott Fraser
(photo IDs: 2126-2127)


(See alsoSnow Goose x Cackling Goose, Snow Goose x Barnacle Goose, Ross's Goose x Canada Goose


Snow Goose Anser caerulescens or Chen caerulescens
Canada Goose Branta canadensis
Lesser Canada Goose Branta candensis parvipes

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