Sunday 23 February 2014

Greylag Goose x Barnacle Goose

Greylag Goose x Barnacle Goose hybrid (individual D), Malmoe (Sweden), 13th May 2009 - copyright Carl Gunnar Gustavsson
(photo ID: 1009)


Five Greylag Goose x Barnacle Goose hybrids were documented by Carl Gunnar in the journal Ornis svecica but some photos can be used here.  The five were labelled individuals A, B, C, D and E.  The first few photos relate to one bird, individual D, presumed to be a female, which has more white on the neck than the others, and an above-average amount of black on the bill.  It is much darker than Greylag Goose and shows a bronzy tone.




Greylag Goose x Barnacle Goose hybrid (individual D, with Greylag Goose), Malmoe (Sweden), 13th May 2009 - copyright Carl Gunnar Gustavsson
(photo IDs: 1005-1008)


Greylag Goose x Barnacle Goose hybrid (individual D, with Greylag Goose), Malmoe (Sweden), 11th May 2009 - copyright Carl Gunnar Gustavsson
(photo ID: 1015)


Greylag Goose x Barnacle Goose hybrid (individual D), Malmoe (Sweden), 28th June 2008 - copyright Carl Gunnar Gustavsson
(photo ID: 1061)


Inidividual E was the darkest of the five.  Carl Gunnar records that the cheek patch changes during the year: from May they usually show a rather even and pale cheek patch but this changes in September when they show a Greylag-like cheek patch colour contrasting with pale white areas as shown in this photo below.  The birds are also darker than in the summer.  Individual E still had an all-black bill nail when its siblings had developed a split-coloured bill nail.  Unlike individual D above, this one has no white speckling on the neck - just some pale feather tips visible at close range.

Greylag Goose x Barnacle Goose hybrid (individual E), Malmoe (Sweden), 2nd October 2009 - copyright Carl Gunnar Gustavsson
(photo ID: 0957)


Here is individual B, showing how the bill nail is becoming paler.

Greylag Goose x Barnacle Goose hybrid (individual B), Malmoe (Sweden), 10th June 2009 - copyright Carl Gunnar Gustavsson
(photo ID: 0993)


And here is the back end of individual C, showing the dark-barred under and upper tail coverts - a feature frequently found on Anser x Branta hybrids.

Greylag Goose x Barnacle Goose hybrid (individual C), Malmoe (Sweden), 28th June 2008 - copyright Carl Gunnar Gustavsson
(photo ID: 1060)


Just as at least one of the Swedish birds was paired to a Greylag Goose (but never produced young - they are probably infertile), so too was this one I observed in Norfolk.  Not only did this appear to be paired to a Greylag Goose but the pair were accompanied by goslings.  The goslings resembled Greylag Goose goslings and, given that we think these hybrids are infertile, I presume they were not the offspring of both accompanying birds (it is not unusual for goslings to be accompanied by geese that are not both their natural parents).

presumed Greylag Goose x Barnacle Goose hybrid, Holkham Park (Norfolk, UK), 22nd November 2004 - copyright Dave Appleton
(photo ID: 0131)



presumed Greylag Goose x Barnacle Goose hybrid (with Greylag Goose gosling), Holkham Park (Norfolk, UK), 14th June 2005 - copyright Dave Appleton
(photo IDs: 0129-0130)


The next one is clearly a Barnacle Goose hybrid, though whether the other parent is Greylag Goose or not is not quite certain.  It is darker than this hybrid often can be, though it is a variable hybrid, and has quite a dark bill - maybe there are some domestic Swan Goose genes involved?  The orange legs on this bird are also a bit of a concern and may indicate that the parent was not simply a Greylag Goose, though at the present time we do not know that this should bar it from being possible.



possible Greylag Goose x Barnacle Goose hybrid (with Greylag Geese), Pipersdijk, Texel (Netherlands), 22nd October 2015 - copyright Joern Lehmhus
(photo IDs: 2317-2319)


This bird was alone and far out on the water so judging its size was impossible.  The extent of white on the face and the dark breast are suggestive of Barnacle Goose.

probable Greylag Goose x Barnacle Goose hybrid, Rutland Water (Rutland, UK), May 2010 - copyright Steve Graby
(photo ID: 1948)


Although some examples of this hybrid inherit a blackish breast like their Barnacle parent, others don't show such a dark breast, like this one.

Greylag Goose x Barnacle Goose hybrid (with Greylag Geese), Texel (Netherlands), July 2016 - copyright Joern Lehmhus
(photo ID: 2900)



Greylag Goose Anser anser
Barnacle Goose Branta leucopsis

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