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Tundra vs taiga bean goose (1 Viewer)
- Thread starter jr_99
- Start date
Alexander Stöhr
Well-known member
Oh,
another thread where I can learn. Joern, Lützen, Lou, Steve, 49bentley, MJB Tom and others, please help! (is there some kind of Batman-calling-beam here in birdforum?)
The right four birds are Taiga imo: when merged into one gruop, they show:
But what is the bird on the left? The bird looks smaller, shorter necked and with much black in the bill. It is long-billed for a Tundra, but within variation for this and the rounded head adds to a bird, that wouldnt stand out in a flock of Tundra BG.
But: it is standing together with a group of Taiga BG at one prime wintering areas for Taiga. Yes, I have seen appearantly "good looking" Tundra BG (for me) together with Taiga, too.
Conclusion? Experts, please help!
Edit: when seen isolated, all four birds would be in the "cant decide-groupt with the level of my experience", I must admit, allthough looking better for Taiga for me. They are not one of those "cartoon-like" Taiga BG with extraordinaire long necks and Swan-goose like head-and bill profiles at the ID-friendly extreme end of range.
another thread where I can learn. Joern, Lützen, Lou, Steve, 49bentley, MJB Tom and others, please help! (is there some kind of Batman-calling-beam here in birdforum?)
The right four birds are Taiga imo: when merged into one gruop, they show:
- the Swan/Pintail long head and a long nosed bill-head profile
- much orange on bill (but its easy to find a Bean Goose with as much orange at the bill like the first and third from left in a large flock of Tundra BG. The second bird seems to have a nearly complete all-pale bill what is rare at best in Tundra? Is that right? Experts, please help with extreme variation)
- the two right birds (and therefore all) lacks the contrasting dark brown head-neck present in many (=typical Tundra BG)
But what is the bird on the left? The bird looks smaller, shorter necked and with much black in the bill. It is long-billed for a Tundra, but within variation for this and the rounded head adds to a bird, that wouldnt stand out in a flock of Tundra BG.
But: it is standing together with a group of Taiga BG at one prime wintering areas for Taiga. Yes, I have seen appearantly "good looking" Tundra BG (for me) together with Taiga, too.
Conclusion? Experts, please help!
Edit: when seen isolated, all four birds would be in the "cant decide-groupt with the level of my experience", I must admit, allthough looking better for Taiga for me. They are not one of those "cartoon-like" Taiga BG with extraordinaire long necks and Swan-goose like head-and bill profiles at the ID-friendly extreme end of range.
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Richard Prior
Halfway up an Alp
Looking at the photo here outside the bat cave I would say that the shape and size of the bill on the left hand bird is different from those of the right hand birds in exactly the way it should be for a Tundra Bean
Cheers,
Robin, err, Rich.
Cheers,
Robin, err, Rich.
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MJB
Well-known member
There has been debate about which subspecies belong to the Tundra and Taiga forms: currently fabalis, johanseni & middendorfii are generally considered Taiga and serrisrostris & rossicus Tundra. Ruokonen et al 2008 proposed full species for middendorfii, but Ruokonen & Aarvak 2011 reverted it to subspecies status.
On the basis of the low genetic differentiation, considerable morphological variation and incomplete reproductive isolation, Ottenburghs et al 2020 argue that the Taiga and the Tundra Bean Goose should be treated as subspecies. Their (summarised) caveat, "Detailed investigations, such as behavioral studies to examine whether assortative mating operates according to plumage phenotypes, have not been performed for the Bean Goose complex. The genomic islands of differentiation uncovered in our study might be associated with morphological and behavioral differences between the Taiga and the Tundra Bean Goose, but this remains to be determined by denser sampling across the range of these taxa and experimental work on their social behavior", pro tem allows, I suggest, that we can remain with recognising 2 species. Ottenburghs et al 2020 found Tundra Bean Goose to be sister of Pink-footed Goose A. brachyrhynchus. Meanwhile the placement of Middendorff's Bean Goose taxon middendorffii is being examined in Russia at present, Jente Ottenburghs in litt.
I would add that the range of individual sizes in any single breeding population appears not to have been assessed, nor has individual plumage variation, which given the remoteness and difficulty of access in the High Arctic, is scarcely surprising. It therefore appear to follow that any set of ID criteria would have difficulty in being successfully applied to every individual in a population; In his fieldwork on gulls in the High Arctic, Pierre Yésou devised criteria by which he could identify percentages of the populations.
In the case of wintering Bean Geese, my view is that unless a 'strange' individual meets known, if limited ID criteria, ID cannot be assigned. Perhaps one of the proper goose ID experts, as Alexander suggested might advise on the limits of current ID data? Me? I just regurgitate references and try to interpret some of the science...!
MJB
Ottenburghs, J, J Honka, GJDM Müskens and H Ellegren. 2020. Recent introgression between Taiga Bean Goose and Tundra Bean Goose results in a largely homogeneous landscape of genetic differentiation. The Genet. Soc. (Heredity): doi.org/10.1038/s41437-020-0322-z
Ruokonen, M, K Litvin and T Aarvak. 2008. Taxonomy of the bean goose-pink-footed goose. Mol. Phyl. Evol. 48: 554-562.
Ruokonen M and T Aarvak. 2011. Typology revisited: historical taxa of the bean goose – pink-footed goose complex. Ardea 99: 103–112
On the basis of the low genetic differentiation, considerable morphological variation and incomplete reproductive isolation, Ottenburghs et al 2020 argue that the Taiga and the Tundra Bean Goose should be treated as subspecies. Their (summarised) caveat, "Detailed investigations, such as behavioral studies to examine whether assortative mating operates according to plumage phenotypes, have not been performed for the Bean Goose complex. The genomic islands of differentiation uncovered in our study might be associated with morphological and behavioral differences between the Taiga and the Tundra Bean Goose, but this remains to be determined by denser sampling across the range of these taxa and experimental work on their social behavior", pro tem allows, I suggest, that we can remain with recognising 2 species. Ottenburghs et al 2020 found Tundra Bean Goose to be sister of Pink-footed Goose A. brachyrhynchus. Meanwhile the placement of Middendorff's Bean Goose taxon middendorffii is being examined in Russia at present, Jente Ottenburghs in litt.
I would add that the range of individual sizes in any single breeding population appears not to have been assessed, nor has individual plumage variation, which given the remoteness and difficulty of access in the High Arctic, is scarcely surprising. It therefore appear to follow that any set of ID criteria would have difficulty in being successfully applied to every individual in a population; In his fieldwork on gulls in the High Arctic, Pierre Yésou devised criteria by which he could identify percentages of the populations.
In the case of wintering Bean Geese, my view is that unless a 'strange' individual meets known, if limited ID criteria, ID cannot be assigned. Perhaps one of the proper goose ID experts, as Alexander suggested might advise on the limits of current ID data? Me? I just regurgitate references and try to interpret some of the science...!
MJB
Ottenburghs, J, J Honka, GJDM Müskens and H Ellegren. 2020. Recent introgression between Taiga Bean Goose and Tundra Bean Goose results in a largely homogeneous landscape of genetic differentiation. The Genet. Soc. (Heredity): doi.org/10.1038/s41437-020-0322-z
Ruokonen, M, K Litvin and T Aarvak. 2008. Taxonomy of the bean goose-pink-footed goose. Mol. Phyl. Evol. 48: 554-562.
Ruokonen M and T Aarvak. 2011. Typology revisited: historical taxa of the bean goose – pink-footed goose complex. Ardea 99: 103–112
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Mark Lew1s
My real name is Mark Lewis
MJB
Well-known member
Taiga Bean Geese for me, for exactly the reasons that Alexander mentions. The left bird is very likely to be a Taiga Bean Goose too, but one that I would have left unidentified if on its own (it still looks better for Taiga than Tundra to me in this picture). It is likely a young bird, although that is something that can be hard to assess this late into spring. I don't think it is particularly hard to identify larger groups of Tundra or Taiga Bean Geese as there are always some birds present that can be safely identified (likely older males) and they have a clear family structure (I agree that there are no such birds present in this picture, but the collective is still convincing for me). Single birds can be extremely hard however, especially when we are talking about the kind of birds that are photographed because they stand out in a very large group. Can't comment on the species versus subspecies discussion, but Middendorff's Bean Goose doesn't really strike me as having all that much in common with (Western) Taiga Bean Goose, but I have to admit that my experience with Middendorff's is limited to pictures/movies only.
Unfortunately I haven't seen a single fabalis in the last 4 years (they have become very rare, and the group that used to winter locally no longer seems to bother leaving Denmark), so I should perhaps consider myself no longer qualified to comment on these threads .......
Cheers,
Lützen
Unfortunately I haven't seen a single fabalis in the last 4 years (they have become very rare, and the group that used to winter locally no longer seems to bother leaving Denmark), so I should perhaps consider myself no longer qualified to comment on these threads .......
Cheers,
Lützen
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