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Thread: presumed 'Richardson's' Canada x Barnacle hybrid on Uist

  1. #1
    Senior Member Martin Scott's Avatar
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    Default presumed 'Richardson's' Canada x Barnacle hybrid on Uist

    http://hebsbirding.wordpress.com/201.../bit-of-cheek/

    An interesting hybrid goose is with several hundred wintering Barnacles on Berneray in the Outer Hebrides/Western Isles.

    It follows on from a regular wintering Richardsons Canada in recent years at the same site.

    MSS
    Last edited by Martin Scott; March 6th, 2011 at 10:15 PM. Reason: spelling

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    I'm sure you are correct - the small size would seem to indicate that of the possible Canada parent, "Richardson's" is the most likely. A "parvipes" type hybrid would surely be larger than this?

    cheers, alan

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    Why isn't it just a Barnacle Goose? Barnies vary in the extent of white on the face - compare the top right and bottom right birds in the group in this one of your pics. Then the "hybrid" is just another Barnie with more extreme black on the head. Nothing else suggests Canada or Cackling Goose inheritance - the grey tones on the flanks and the black bars on the back are typical Barnie, the extent of the black on the chest is typical Barnie. If it was a hybrid, I'd expect browner flanks, less obvious black barring on the back, and the black on the chest not extending so far down.

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    Senior Member appleton.dave's Avatar
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    I'm interested in this as I discovered a presumed hybrid between a Barnacle Goose and a Richardson's Canada Goose among the Pink-footed Geese wintering in Norfolk this year. Some photos of that bird on my website.

    The Norfolk bird differed from the Hebrides bird in a number of ways. The upperparts were much more obviously brown toned, the flanks were more dirty brown and the lower part of the breast was dark brown, merging gradually into the black neck. Those are all typical features of hybrids between Barnacle Goose and either species of Canada Goose (the more Barnacle-like ones - a few can be more Canada-like). Although the Hebrides bird appears to show a dark line under the chin dividing the pale strap, the rear edge of the chin strap appears to go straight down as it does on Barnacle, not curving forwards towards the chin as it tends to on Canada/Cackling as well as many hybrids.

    Not all hybrids show all of those features but I'm a little surprised the Hebrides bird doesn't show more of them if it is indeed a first-generation hybrid. Having said that, most of my experience of these hybrids, whether in life or in photos, relates to adults, whereas I think the Hebrides bird is a juvenile. However it does seem to be at the most Barnacle-like extreme of variation in hybrids and that makes me wonder whether it might in fact be the result of a hybrid backcrossed with a Barnacle Goose, assuming it is not just a Barnacle Goose.

    I would caution against placing too much significance in the fact that it is reported as being 10% smaller than the Barnacle Geese - I'm not clear that it's any smaller than I'd expect a small juvenile Barnacle Goose to be.

    If it wasn't for the one or two photos that appear to show a dark dividing line under the chin strap I'd be asking the same as Michael - why isn't this an odd juvenile Barnacle Goose? One or two photos appear to show too much brown in the upperparts - but others seem perfectly fine for juvenile Barnacle Goose. I wasn't sure if Barnacle could show quite so much black through the eye, but even adults can come close - e.g. the one in the photo labelled "DSC03828 variation n barnacle face patterns". But that dark line under the chin - can pure Barnacles ever show this - or could photos make it look that convincing that it exists when it isn't really there? (I ask the last question because I know photos can make it look fairly convincing that it exists when it isn't really there).

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    I'd probably be inclined to agree with you Dave, in that the Hebs bird may well be a 2nd-generation plus hybrid. Though genes are a funny thing, and a1st-generation hybrid could conceivably come out like this if the Barnacle genes 'in the mix' predominate.

    Anyway, over the last decade, I've seen about half a dozen presumed parvipes/hutchinsii x Barnacle Geese hybrids on Islay - including a family party that associated with quite a large parvipes and its mate at Mulindry. All of these birds have shown warmish tones to the mantle and flanks, more so than on the Hebs bird. Additionally, each hybrid I've seen shows a necksock extending onto the breast with a clear demarcation as in a Barnacle Goose.

    I've attached a few shots of a couple of hybrids I photographed on Islay in December 2009. These are of unknown parentage, although they were in fields where the aforementioned family used to reside... and their size may also indicate parvipes parentage on one side.
    Attached Images Attached Images

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    Member Alcedo atthis's Avatar
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    Concerning hybrids, from the birds i have seen in recent years, I am not sure if it is always possible in later generations to safely identify birds with canadensis genes from birds with hutchinsii genes.

    However, my feel is that such not pure barnacle geese (with either canadensis or hutchinsii genes) have been increasing in recent years in Middle Europe (Netherlands, Northern Germany, parts of Scandinavia), probably following the range expansion of Barnacle goose.
    But how much of a problem is this? How successfull are these hybrids? Could they pose a problem to the Barnacle goose population?
    What impressions are there from other regions?

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