Crossbills (2 Viewers)

Richard Klim · Apr 10, 2014

'Rubrifasciata'

JustinJansen said:
Roselaar C S 2014. Are 'rubifasciata' crossbills of hybrid origin? Dutch Birding 36 (2): 96-107.

As I was reading Justin's post, I heard a thud at the door and found that Dutch Birding 36(2) had arrived!

... This morph was described by Bonaparte & Temminck in 1850, based on bird(s) with white or pink wing-bars collected by C L Brehm. From captures in central eastern Germany, it is estimated to occur in a ratio of c 1:4000 among crossbills ...
... In view of the individual variability of 'rubrifasciata', this morph cannot be an entity of its own but appears to be the result of hybridisation between Two-barred and Red, with some characters of one parent dominating in some birds and of the other parent in other. ...

Richard Klim · Jun 10, 2014

Spain

Arizaga, Alonso & Hobson (in press). Disentangling the origin of crossbills using morphology and isotopic (δ2H) characters. Are southern European crossbills restricted to population-specific key resources? J Ornithol. [abstract]

Richard Klim · Jul 3, 2014

Newfoundland

Daniel Philippe said:
North American Ornithological Conference – Vancouver 2012 PS2.19
Hynes, Doug, (Memorial University of Newfoundland, St. John's, Canada); Miller, Ted (Memorial University of Newfoundland, St. John's, NF, Canada)
VOCALIZATIONS OF RED CROSSBILLS (LOXIA CURVIROSTRA) IN NEWFOUNDLAND

Hynes & Miller 2014. Vocal distinctiveness of the Red Crossbill (Loxia curvirostra) on the island of Newfoundland, Canada. Auk 131(3): 421–433. [abstract]

Richard Klim · Oct 1, 2014

Southern California

Szeliga, Benner, Garrett & Ellsworth 2014. Call types of the Red Crossbill in the San Gabriel, San Bernardino, and San Jacinto Mountains, southern California. Western Birds 45(3). [abstracts]

Farnboro John · Oct 1, 2014

Until I see some work defining the limits of Crossbill calls in terms of frequency, length etc variation, and comparative studies of e.g. Chaffinch and Great Tit (both known for dialect variation) that comes to a distinct conclusion that states unequivocally that Crossbills exceed by a wide margin the variation in either of those species or indeed any others I haven't thought of, I shall continue to believe that all of this stuff is completely useless rubbish. Common Crossbill is a single widespread species which may or may not have sufficient overlap to include Parrot and Scottish, and Two-barred is undoubtedly a separate species.

I have now encountered large numbers of birders with unimpaired hearing who are, when under any pressure at all (by which I mean other observers present) are completely unable to identify any Crossbill call as coming from a particular variant. Indeed, their own language and tone indicates that they are desperate for support from those nearby (my hearing is not unimpaired but is good enough for that sort of nuance.)

As other Crossbills listen to these calls using essentially the same equipment as we do, and not with the benefit of sonograms, instant replay of recording devices etc, I conclude that they make decisions on them just as we do. While I sometimes have difficulty understanding the accents of Consett, Glasgow and Widdecombe-in-the-Moor, I have no difficulty identifying them as British: and I believe the same is true of the range of calls coming from Common Crossbills.

John

Nutcracker · Oct 2, 2014

Farnboro John said:
and Two-barred is undoubtedly a separate species.

Why stop there with two species? Seems a bit illogical to me, and as far as I'm aware, it isn't supported by genetic data. To continue the Chaffinch analogy, UK and Moroccan or Canary Island Chaffinches differ more obviously from each other than Common and Two-barred Crossbills do from each other. Yet genetic data has shown no support for a split of N African or Canary Island Chaffinch populations.

As an aside: Scottish Crossbill is defined by a specimen shot in 1904. What was its call type? Are current "Scottish Crossbills", only identifiable by call, the same taxon as the 1904 type specimen? :flyaway:

lewis20126 · Oct 2, 2014

Nutcracker said:
As an aside: Scottish Crossbill is defined by a specimen shot in 1904. What was its call type? Are current "Scottish Crossbills", only identifiable by call, the same taxon as the 1904 type specimen? :flyaway:

Scottish Crossbill is real enigma. What other extant endemic in a modern country with excellent access to the habitat is so difficult to to see? It is all very odd. It really should be removed from the checklists until there has been a compehensive review of all plain-winged Loxia forms.

cheers, alan

Nutcracker · Oct 2, 2014

lewis20126 said:
Scottish Crossbill is real enigma. What other extant endemic in a modern country with excellent access to the habitat is so difficult to to see? It is all very odd. It really should be removed from the checklists until there has been a compehensive review of all plain-winged Loxia forms.

cheers, alan

Yep :t:

It's very easy to be critical of the UK400 Club list, but in this instance, they're right to exclude it as a species.

Richard Klim · Oct 2, 2014

lewis20126 said:
Scottish Crossbill is real enigma. What other extant endemic in a modern country with excellent access to the habitat is so difficult to to see? It is all very odd. It really should be removed from the checklists until there has been a compehensive review of all plain-winged Loxia forms.

Indeed! Given the huge circumpolar complex of overlapping cryptic subspecies/races/call types, it's surely inconsistent and premature to elevate this (still poorly understood?) example to specific status. But who's going to stick their neck out and formally propose the demotion of Britain's only endemic avian 'species'...?

l_raty · Oct 2, 2014

Nutcracker said:
As an aside: Scottish Crossbill is defined by a specimen shot in 1904. What was its call type? Are current "Scottish Crossbills", only identifiable by call, the same taxon as the 1904 type specimen? :flyaway:

I have always thought that there was a quite distinct possibility for the breeding birds now called "Parrot Crossbills", to be in fact the direct descendents of the original pine-adapted Scottish Loxia population. Now with an increased bill size due to decades of systematic preferential emigration of small-billed individuals, which feed more easily on alien conifer plantations.
Just a wild guess that might be completely wrong as well, of course...

jalid · Oct 2, 2014

Farnboro John said:
I have now encountered large numbers of birders with unimpaired hearing who are, when under any pressure at all (by which I mean other observers present) are completely unable to identify any Crossbill call as coming from a particular variant. Indeed, their own language and tone indicates that they are desperate for support from those nearby (my hearing is not unimpaired but is good enough for that sort of nuance.)

I think that most, if not all, birdwatchers who I know and who have been interested enough to try seriously, have learned to separate the most common types here (C, X and Parrot C). Of course, rarer varieties and mixed flocks are much harder.

I am convinced that the call types of crossbills are "something", if not conventional species. And in any case it is necessary to understand the variation of Common Crossbill calls in order to identify Parrot Crossbill (that 'variety' which has long known history of sympatric breeding and distinctly differing morphometrics).

Farnboro John · Oct 2, 2014

jalid said:
I think that most, if not all, birdwatchers who I know and who have been interested enough to try seriously, have learned to separate the most common types here (C, X and Parrot C). Of course, rarer varieties and mixed flocks are much harder.

I am convinced that the call types of crossbills are "something", if not conventional species. And in any case it is necessary to understand the variation of Common Crossbill calls in order to identify Parrot Crossbill (that 'variety' which has long known history of sympatric breeding and distinctly differing morphometrics).

Just a small clarification request: do you mean that it is necessary to understand Common Crossbill calls in order to identify Parrot Crossbill by call, or that it is impossible to identify Parrot Crossbill except by call?

John

jalid · Oct 2, 2014

Farnboro John said:
Just a small clarification request: do you mean that it is necessary to understand Common Crossbill calls in order to identify Parrot Crossbill by call, or that it is impossible to identify Parrot Crossbill except by call?

The first option. Parrot Crossbill is possible to identify from its larger bill and head and general size (but not always easy). Sometimes, when both species are in migration together, it is possible to pick larger headed Parrot Crossbills in flight, even without hearing the call (otherwise it would be very difficult to count mixed flocks).

Farnboro John · Oct 2, 2014

jalid said:
The first option. Parrot Crossbill is possible to identify from its larger bill and head and general size (but not always easy). Sometimes, when both species are in migration together, it is possible to pick larger headed Parrot Crossbills in flight, even without hearing the call (otherwise it would be very difficult to count mixed flocks).

Thank you. That's what I thought. All the Parrots I've seen recently have been not only disproportionately large-billed and headed, but about the size of a house.

John

jurek · Oct 2, 2014

l_raty said:
I have always thought that there was a quite distinct possibility for the breeding birds now called "Parrot Crossbills", to be in fact the direct descendents of the original pine-adapted Scottish Loxia population. Now with an increased bill size due to decades of systematic preferential emigration of small-billed individuals, which feed more easily on alien conifer plantations.

This is impossible to verify, nor it is possible to tell what today form is represented by the type specimen of "scotica", because there is apparently no genetic difference separating them. It is really "make-believe" species.

l_raty · Oct 3, 2014

jurek said:
because there is apparently no genetic difference separating them.

There is apparently no genetic differences "in the UK".
I've attached what cox1 shows (data mainly from Scandinavia, Russia and Japan). It's clearly not enough to draw a strong conclusion. But, although the segregation does not appear complete, what I see does not really look like the global mixture that was described from Scotland either...

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PS - Just ran across [this MS thesis], which says:

In addition, a study performed by Growth (2000 unpubl.) of finches including four species of Loxia and one of Carduelis. For which, the region spanning the cyt b, NADH6, control region, and 12S ribosomal RNA genes was sequenced, unexpectedly showed that variation within the NADH6 gene (3.7%) was higher than in the control region (1.6%), and that variation within the control region was not higher than in the cyt b gene (1.6%) (GenBank accession numbers AF171652-AF171664). Therefore, it was not assumed in this study that the control region would be the most informative mtDNA region for this study.

(I knew the sequences, but had never actually checked this. The author is Groth, of course, not "Growth"; the study was indeed never published.) It's interesting, because this suggests that the mitochondrial marker used by Piertney et al. in Scotland may not have been a happy choice.

Farnboro John · Oct 4, 2014

l_raty said:
There is apparently no genetic differences "in the UK".
I've attached what cox1 shows (data mainly from Scandinavia, Russia and Japan). It's clearly not enough to draw a strong conclusion. But, although the segregation does not appear complete, what I see does not really look like the global mixture that was described from Scotland either...

-------------
PS - Just ran across [this MS thesis], which says:

(I knew the sequences, but had never actually checked this. The author is Groth, of course, not "Growth"; the study was indeed never published.) It's interesting, because this suggests that the mitochondrial marker used by Piertney et al. in Scotland may not have been a happy choice.

Well, dohh...

Genes from different areas of the DNA molecule vary differently depending what is being looked at - in other words, genes affecting more variable characters vary more greatly. The consequence being that measuring the same gene for a lot of different applications isn't a particularly effective system - surprise!

John

l_raty · Oct 4, 2014

Well...

Various parts of the mtDNA molecule have various functions. Some code for proteins (will be transcribed into a messenger-RNA, which will then be translated into a protein), others for ribosomal- and transfer-RNAs (transcribed but not translated; have a function in the translation of mRNAs into proteins), others, still, are non-coding. The variability of a given part of the DNA molecule largely depends on functional constraints. For protein-coding DNA (such as NADH6), constraints will be strong because the genes must continue to code for a functional protein. On the other hand, the part known as "control region" is non-coding; this part includes domains that are usually "hypervariable" (= which vary a lot). The parts of the DNA that vary a lot are good to reconstruct very recent events, because these will have a stronger signal, while more slowly-evolving parts may barely vary at all. (Eg., it's a hypervariable domain of the control region that has been used to reconstruct most of the evolution of large white-headed Larus.)

Choosing the control region to study Loxia was rather logical, under the assumption that this region is highly variable, and if the forms were assumed to be closely interrelated. But if, for whatever reason, the control region in Loxia actually ends up varying much less than usual--less than some coding-genes--this choice was unfortunate. This could potentially result in the whole group appearing much more "genetically uniform" in the analyzes than it really is.

('Hope this is makes sense...)

Farnboro John · Oct 4, 2014

l_raty said:
Well...

Various parts of the mtDNA molecule have various functions. Some code for proteins (will be transcribed into a messenger-RNA, which will then be translated into a protein), others for ribosomal- and transfer-RNAs (transcribed but not translated; have a function in the translation of mRNAs into proteins), others, still, are non-coding. The variability of a given part of the DNA molecule largely depends on functional constraints. For protein-coding DNA (such as NADH6), constraints will be strong because the genes must continue to code for a functional protein. On the other hand, the part known as "control region" is non-coding; this part includes domains that are usually "hypervariable" (= which vary a lot). The parts of the DNA that vary a lot are good to reconstruct very recent events, because these will have a stronger signal, while more slowly-evolving parts may barely vary at all. (Eg., it's a hypervariable domain of the control region that has been used to reconstruct most of the evolution of large white-headed Larus.)

Choosing the control region to study Loxia was rather logical, under the assumption that this region is highly variable, and if the forms were assumed to be closely interrelated. But if, for whatever reason, the control region in Loxia actually ends up varying much less than usual--less than some coding-genes--this choice was unfortunate. This could potentially result in the whole group appearing much more "genetically uniform" in the analyzes than it really is.

('Hope this is makes sense...)

Yes, thank you for a clear explanation. I do understand that as we crawl forward into the realms of investigating speciation at the genetic level there are going to be reverses like this (if that's not putting it a bit strongly) on individual investigations. Researchers must understand that if you get a strongly counter-intuitive answer it probably means you are looking at the wrong dataset (i.e. your basic assumption about where the strongest messages will be is wrong) and rather than trying to make sense of the answer, the pointer may be to a need for more research looking at a different gene. I think!

John

Farnboro John · Oct 5, 2014

..... of course an alternative view might be that the choice of region was indeed appropriate, Crossbills are genetically quite uniform and all the stuff about call types and millions of species is complete b******s!

John

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