BLI recognised Loxia scotia no longer as species

[Melanie]

http://www.birdlifeforums.org/WebX?13@@.2cba6aeb

[Richard Klim]

I've always felt that recognition of Loxia scotica Scottish Crossbill was something of an anomaly (driven partly by conservation interests, and perhaps even the desire in Britain to have an least one endemic species!). It will be interesting to see if there is any reaction from BOURC.

Actually it's rather ironic that BirdLife has chosen "to follow the approach of the AOU in recognising one species of Red Crossbill" just when AOU-NACC is considering a proposal to recognise L sinesciuris South Hills Crossbill.

But although BirdLife has now lumped it with L curvirostra Common/Red Crossbill, perhaps there is an alternative case for its treatment as a race of L pytyopsittacus Parrot Crossbill (eg, as per UK400 Club)?

Richard

[Jos Stratford]

perhaps even the desire in Britain to have an least one endemic species...

Start a 'Liberate the Red Grouse' campaign to replace it?

[Richard Klim]

Start a 'Liberate the Red Grouse' campaign to replace it?
Why not indeed? The cold war's over - there shouldn't be any objections to a left-leaning species in these more enlightened times. ;)

It would certainly provide a more safely tickable substitute!

Richard

[l_raty]

Why not indeed? The cold war's over - there shouldn't be any objections to a left-leaning species in these more enlightened times. ;)

It would certainly provide a more safely tickable substitute!

But this doesn't coincide with the main phylogeographic break in Willow Grouse, which IIRC is between NE America and the rest of the world...

L -

[chris butterworth]

I was wondering about the link with the AOU's approach to "Red" Crossbill ( I've also wondered about a lot of their recent "splits", but thats besides the question ). Perhaps I shouldn't have read this thread as I finally got to grips with Crossbills in Scotland this year and definitly got "Scottish". Bu**er.
Chris

[jurek]

I've always felt that recognition of Loxia scotica Scottish Crossbill was something of an anomaly (driven partly by conservation interests, and perhaps even the desire in Britain to have an least one endemic species!). It will be interesting to see if there is any reaction from BOURC.

Cannot agree more! Especially now that we know that there is no genetic difference at all between these three crossbills; that Parrot, Scottish and Common crossbills became practically unrecognizable when they breed together in Scotland, and that crossbills trapped in England with measurements fitting Scottish Crossbills are left unidentified.

But although BirdLife has now lumped it with L curvirostra Common/Red Crossbill, perhaps there is an alternative case for its treatment as a race of L pytyopsittacus Parrot Crossbill (eg, as per UK400 Club)?

Unfortunately, genetics says there is no difference. So, no reason to claim that Scottish and Parrot Crossbills are more related to each other than to other crossbills.

Parrot Crossbill is itself on a trajectory to be lumped as a characteristic ecological race of Common Crossbill. Not a common thing, but not unusual either. It would be interesting to hear if Scandinavians did some studies on it vs local Common Crossbills.

So, British flag-waving patriotic birders must satisfy themselves with ticking any of the numerous wonderful endemics found in British overseas territories. Falkland Steamer-Duck ROXXS!!!

[Richard Klim]

So, British flag-waving patriotic birders must satisfy themselves with ticking any of the numerous wonderful endemics found in British overseas territories.
Well, they will need to be quick. Regrettably our authorities seem to have little interest in the rapidly deteriorating prospects of the many globally endangered or threatened species in the UK Overseas Territories (UKOTs). :C

Richard

[njlarsen]

Cannot agree more! Especially now that we know that there is no genetic difference at all between these three crossbills; that Parrot, Scottish and Common crossbills became practically unrecognizable when they breed together in Scotland, and that crossbills trapped in England with measurements fitting Scottish Crossbills are left unidentified.



Unfortunately, genetics says there is no difference. So, no reason to claim that Scottish and Parrot Crossbills are more related to each other than to other crossbills.

Parrot Crossbill is itself on a trajectory to be lumped as a characteristic ecological race of Common Crossbill. Not a common thing, but not unusual either. It would be interesting to hear if Scandinavians did some studies on it vs local Common Crossbills.

So, British flag-waving patriotic birders must satisfy themselves with ticking any of the numerous wonderful endemics found in British overseas territories. Falkland Steamer-Duck ROXXS!!!

I thought I read somewhere that Common and Parrot Xbills do seem to behave as good biological species, even when they breed in the same areas after invasions. Ignoring such information and lump them would indeed seem odd!

Niels

[Daniel Philippe]

Unfortunately, genetics says there is no difference. So, no reason to claim that Scottish and Parrot Crossbills are more related to each other than to other crossbills.


IMHO genetic distance alone is not enough to assign species ranks. In which case the Galapagos finches would be one species only.

[bombycilla]

No significant genetic differences have been discovered amongst European Crossbills using the methods that were employed back then (mitochondrial). My understanding is that more work is to be carried out using more refined techniques and differences may then be found for Scottish Crossbill.

Genetics are only part of the picture anyway and should not be exclusive in defining speciation of crossbills (or any other taxa) - lack of genetic differences are often abused by sceptics and anti-splitters !

Parrot Crossbill is not a 'race' of Common Crossbill. It may be related to an ancestral 'common' crossbill form way, way back but to say in 2009 that it is a race of Common Crossbill is total cobblers - it is different biometrically (inc. plumage), has different calls and song, feeds on different conifers and generally breeds assortatively and moults completely asynchronous to curvirostra (where they co-exist). If it is not a 'species' then it sure as heck is acting as one.

The Scottish Crossbill apparently does exist.............it's just some folks don't seem to know which one it is ! See HERE (http://pinemuncher.blogspot.com/2009_05_01_archive.html). And HERE (http://pinemuncher.blogspot.com/search?updated-min=2009-01-01T00%3A00%3A00Z&updated-max=2010-01-01T00%3A00%3A00Z&max-results=20).

Bob.

[Xenospiza]

With more refined techniques you can find all kinds of differences between populations of all kinds of birds...

I guess it's either one “Red Crossbill” or many... (I quite enjoyed trying to identify an odd-calling crossbill last weekend), but not “Common + Parrot + Scottish”.

[Richard Klim]

I guess it's either one "Red Crossbill" or many..., but not "Common + Parrot + Scottish".
Yes, as reflected in AOU's current position (Check-list 7th Edition)...
"Apparently at least nine species, differing in morphology and vocalizations, exist in North America, with some breeding sympatrically and mating assortatively"

...but sensibly awaiting evidence of the bigger picture before making one-off localised splits (except for the impending decision on sinesciuris!).

Richard

[jurek]

Well, Scottish Crossbills are different, but simply not enough to be called a species.

Lack of genetic differences means (for me) that these forms don't exist long and there is no time to accumulate genetic differences. They form when particular conifer seeds occur, and later crossbreed and lump again.

But I think we had similar discussion in another thread.

Fascinating and beautiful birds, anyway.

[bombycilla]

They form when particular conifer seeds occur, and later crossbreed and lump again.


Please provide your evidence for this cross breeding. Most studies I have read conclude that crossbills mate (positive) assortatively ! Your theory would also not also explain the 9 ( or 10) Red Crossbill types in the USA that all have different bill morphology ( and even genetic differences I bekieve !).

Your argument is not implausible, but without large amounts of anectodal or scientific data describing cross-breeding on a larger scale that would allow genetic indifference, then it seems unlikely, especially so between Common and Parrot Crossbill.

B.

[jurek]

I meant that lack of known genetic differences speaks for the gene flow.

[bombycilla]

I meant that lack of known genetic differences speaks for the gene flow.

"Known" being the operative word ! I also have to take issue at your previous statement that Common, Scottish and Parrot Crossbill became "practically unrecognizable" when they breed together in Scotland. Firstly, they do not breed with each other ( cross breed ) as a rule and secondly those working on these species have no trouble differentiating them either by call, plumage or morphology ( jizz).

The Birdlife decision is all the more strange given RSPB are a partner. I can't see RSPB being happy with this stance given all the work to promote Scottish Crossbill as a species.

If the AOU checklist recoginzes 9 species of Red Crossbill in America why are Birdlife quoting that they are following this example ? Am I missing something ?

[njlarsen]

If the AOU checklist recoginzes 9 species of Red Crossbill in America why are Birdlife quoting that they are following this example ? Am I missing something ?

I think that is an exaggeration. There is a current proposal (http://www.birdforum.net/showthread.php?t=149155)to recognize South Hills Crossbill, and the others have been mentioned in papers but not brought before AOU as far as I know.

Niels

[Richard Klim]

If the AOU checklist recoginzes 9 species of Red Crossbill in America why are Birdlife quoting that they are following this example ? Am I missing something ?
The current AOU Check-list acknowledges that there are probably many species involved within Red/Common Crossbill, but only formally recognises L curvirostra for now, pending further research:

Apparently at least nine species, differing in morphology and vocalizations, exist in North America, with some breeding sympatrically and mating assortatively (Groth 1988, 1993a, 1993b); however, morphological overlap among some species currently prevents assignment with certainty of some existing type specimens to the groups defined by call types (Groth 1993a). Additional species-level taxa almost certainly exist among the populations outside North America currently assigned to Loxia curvirostra (Groth 1993a).
http://www.aou.org/checklist/north/pdf/AOUchecklistSturn-Estril.pdf (p663)

So it will be interesting to see the result of the pending NACC proposal to recognise L sinesciuris, which would conflict with the policy (so far) of avoiding piecemeal splitting.

Richard

[Richard Klim]

...although BirdLife has now lumped it with L curvirostra Common/Red Crossbill, perhaps there is an alternative case for its treatment as a race of L pytyopsittacus Parrot Crossbill...
Actually, BirdLife's own species account for Loxia scotica implied that the latter treatment may be more appropriate:

"Recent work on flight and excitement calls suggest that it can be distinguished from Common Crossbill L. curvirostra but whether it is distinct from Parrot Crossbill L. pytyopsittacus remains unclear."
http://www.birdlife.org/datazone/species/index.html?action=SpcHTMDetails.asp&sid=8877&m=0

Richard

[jurek]

"Known" being the operative word !

Sorry, I cannot imagine how genetics would work piece-by-piece: identical mtDNA but no cross-breeding and species-level variation in other DNA.

[Mysticete]

If a split is recent enough there can be very little to no genetic differentiation in mitochondrial DNA while still representing biologically distinct taxa. IIRC, Ross/Snow Geese and members of the White-headed Gull group have little if no genetic differences in mitochondrial DNA but are widely considered good species. I don't know enough about European crossbills to give an opinion on the Scottish Crossbill, but if I recall correctly the South Hills Crossbill is not very distinct genetically from the other NA crossbills, yet assortatively mates and otherwise passes all the test for a BSC species.

[njlarsen]

Sorry, I cannot imagine how genetics would work piece-by-piece: identical mtDNA but no cross-breeding and species-level variation in other DNA.

One of the explanations I have seen given for such a scenario is introgression, which can basically be the result of a single hybridization event, where the hybrid backcrosses with the other population and thereby brings the mtDNA into the other species. I cannot remember the details off the top of my head but haven't there been examples of much larger sequence differences in nuclear genes than in mtDNA which more or less proves the above scenario?

In the example of screws we discussed on another thread, there is even examples of piecemeal migration of nuclear genes (introgression working much faster on some chromosomes than others).

Niels

[bombycilla]

Sorry, I cannot imagine how genetics would work piece-by-piece: identical mtDNA but no cross-breeding and species-level variation in other DNA.

Mitochondrial DNA was used for the crossbill genetics. Mitochondrial DNA is represenative of 0.001 % of the genome. That leaves 99.999 % where a more significant difference may exist. Also, the mtDNA was not "identical" between samples as you quote, though granted not enough difference that would be expected between species ( on a 'genetic' level).

However, a recently diverged 'species' may not show large differences in mtDNA and this may be the case with the crossbills - thousands of years of ecological divergence rather than millions of years.

If we pin our colours on crossbill speciation to the masts of the white lab coated phylogenetic scientists, most of whom won't even have seen a live crossbill, then they (crossbills) are not species. If however, we wish to instead favour the data and evidence provided by the field biologists who are stuying crossbill ecology then it would seem they are 'good' species, and are certainly at the very least behaving as species.

You seem to favour the lab scientists test tubes, which I totally respect. I on the other hand favour the morphological, behavioural and ecological evidence as it is something I can see through my bins in the absence of a personal genetic laboratory !

[Mysticete]

I know researchers that do both lab and field work on crossbill speciation, so I don't think there is a dichotomy.

At any rate, I think the real reason why people don't favor splitting crossbills is that I think it horrifies birders that there might be (for example in the US) 9 or so species of bird which might be virtually impossible to identify and tick correctly in the field, and no one wants to throw down Red Crossbill Loxia sp. on their checklist. At the very least, Crossbills are just a valid split if not more so than many other bird complexes that people like to sort out, such as Juncos or White-crowned Sparrows. Granted, I think more research needs to be done before piece meal splitting (i.e. South Hills or Scottish Crossbills), but complaining about splitting crossbills and happily accepting every slight Gull form as a new species is a bit hypocritical.

[bombycilla]

I know researchers that do both lab and field work on crossbill speciation, so I don't think there is a dichotomy.

At any rate, I think the real reason why people don't favor splitting crossbills is that I think it horrifies birders that there might be (for example in the US) 9 or so species of bird which might be virtually impossible to identify and tick correctly in the field, and no one wants to throw down Red Crossbill Loxia sp. on their checklist. At the very least, Crossbills are just a valid split if not more so than many other bird complexes that people like to sort out, such as Juncos or White-crowned Sparrows. Granted, I think more research needs to be done before piece meal splitting (i.e. South Hills or Scottish Crossbills), but complaining about splitting crossbills and happily accepting every slight Gull form as a new species is a bit hypocritical.

Without sounding defensive regarding the lab coat researchers, I did say "most of whom" ;) I have certainly read a few 'desk ornithologist' papers on Loxia, basically literature reviews of other work.

I agree totally with all your points.

[chris butterworth]

At any rate, I think the real reason why people don't favor splitting crossbills is that I think it horrifies birders that there might be (for example in the US) 9 or so species of bird which might be virtually impossible to identify and tick correctly in the field, and no one wants to throw down Red Crossbill Loxia sp. on their checklist.

I've a horrible feeling you've just hit the nail on it's pointy little head.
Chris

[njlarsen]

Well, I have browsed quite a bit on the SACC proposal pages lately, and they repeatedly bring up the "diagnosability" issue when discussing if a species can be recognized ...

Niels

[Mysticete]

I wonder how important diagnosability is for defining species though. Birders have it quite easy, but there are many cryptic mammal and herp species which are only diagnosable by chromosome, teeth, or other hard to access in the field features. My guess is that the Crossbills forms are not that bad, but just require "in hand" identification. I would think many seabirds might also run afoul of the diagnosability problem as well (recent suggested Storm Petrel splits are just as scary as the crossbill splits in my opinion).

[bombycilla]

I can respect the 'diagnosability' issue birders face with Loxia. However, whilst Common and Scottish Crossbills may be potentially confused (visually) where they occur together, Parrot is quite distinct.

Scottish calls are distinctive and can learned by anyone who can be bothered to spend the time - their flight calls have an extra component (which you hear) and their excitement calls sound nothing like those of Parrot Crossbill and can only really be confused with EcE ( glip) Common Calls ( whose own flight calls sound nothing like Scottish flight calls).

In the hand identification whilst useful as a diagnosing tool for crossbills is also potentially fraught with difficulties as there is often some natural variation within a population ( which may overlap with another type) and as such outliers at both extremes may be difficult to classify, or may be classified wrongly on this method alone. An example of this would be a male Crossbill with bill depth 12.3mm in NE Scotland - it could be a big Scottish or small Parrot. Then, the use of its release call may become more significant. But then do you classify on this factor alone...... ? !

[jurek]

Birds actually seem more 'oversplit' than mammals, herps or insects.

Precisely because twitchers push for splitting everything recognizable in the field.

Recently has been a push to split primates - with open admiting that it would increase their conservation interest. Red colobus turned into 9 species etc. Unfortunately, this seemed to work only in an internal circle of primatologists. Conservation in the field is still going precisely only as much as local NGOs and corruption allows. And African people didn't give up eating their favorite monkeys because they are different species. :/

[Xenospiza]

can only really be confused with EcE ( glip) Common Calls

I've never understood Summers' terminology, but if I check http://en.wikipedia.org/wiki/Common_Crossbill, I guess it starts to dawn on me:

Ec = Excitement call (letters)
Fc = Flight call (numbers)

But what would (say) the rather distinct Bohemian then be? No numbers/letters assigned yet?

Time for a CD with Dutch Birding with the "other" codes!

[Mysticete]

Or, you can argue that mammals and insects are undersplit...

[bombycilla]

But what would (say) the rather distinct Bohemian then be? No numbers/letters assigned yet?


Probaby a 5D. It has a EcD (type), though different from Parrot and a Fc that has not been found in Britain so would possibly be assigned a new number. Fc2 is already shared between Parrot and 'Wandering' Common types.

To be fair Ron Summers described only the calls he found in Britain, following a similar system as those used by Groth in the US. Presumably, he didn't assume that a Fc would be exclusive to one Ec type ( which it isn't eg. 'parakeet' is a 1B ), so both are categorized.

It is confusing, the 'Dutch' and 'British' systems. The problems of sonograms is that the 'classification' of their features can be just as troublesome as morphology, and it is possible to 'split' and 'split' to ludicrous extremes !

[njlarsen]

Birds actually seem more 'oversplit' than mammals, herps or insects.


whether something is oversplit or undersplit to my mind is a question of two things: personal preference and species concept. I read earlier today the introduction to AOU checklist no 7 (I think it was) where the authors pointed out the difference in interpretation that they used compared to authors of earlier versions: if there was a narrow, stable hybridization zone, earlier authors had interpreted that as evidence against two species according to the biological species concept, because their predecessors had felt that any hybridization was sign of gene flow; for this group, the same observation would indicate evidence for two species, because a narrow hybrid zone was interpreted as an essential barrier to gene flow. Their predecessors had required an absolute barrier (no hybridization what so ever which would indicate that there would be only one species of ducks in the world (my exaggerated example, not theirs)).

Cheers
Niels

[davercox]

Well, I have browsed quite a bit on the SACC proposal pages lately, and they repeatedly bring up the "diagnosability" issue when discussing if a species can be recognized ...

Niels

I'm not a scientist but surely 'diagnosability' matters only to other Crossbills.

[Xenospiza]

I'm not a scientist but surely 'diagnosability' matters only to other Crossbills.
And since assortive mating has been proven for various call types, this must be the case!

[colonelboris]

Tick 'em all and let god sort them out!

I'll get me coat...

[Farnboro John]

I've a horrible feeling you've just hit the nail on it's pointy little head.
Chris

If your nail has a pointy head you should probably try it the other way up.

John

[Peter C.]

If your nail has a pointy head you should probably try it the other way up.John

:clap::clap::clap:

Yes, they do work better that way....

[Gentoo]

I think it horrifies birders that there might be (for example in the US) 9 or so species of bird which might be virtually impossible to identify and tick correctly in the field, and no one wants to throw down Red Crossbill Loxia sp. on their checklist.Why not? It may distract them from the Empidonax conundrum

[chris butterworth]

:clap::clap::clap:

Yes, they do work better that way....

In a dicussion about Crossbill taxonomy you are bound to be wrong, whatever end you choose! :t:
Chris

[chris butterworth]

[QUOTE=Mysticete;1600978]Birders have it quite easy, but there are many cryptic mammal and herp species which are only diagnosable by chromosome, teeth, or other hard to access in the field features. QUOTE]
BIRDERS HAVE IT QUITE EASY!!!! There will be a line of them outside your front door, waiting to introduce you to Mr. Big Stick for saying something like that. On the other hand I "do" molluscs and the things you have to do to identify slugs would have a birder reaching for the sedative bottle!
Chris

[Mysticete]

I would much rather have to identify an empid flycatcher or sort through gulls then try to field identify southwestern Deermice, bats in flight without anabat, or any shrew!

[Richard Klim]

Hmm, the plot thickens.

The post stating that BirdLife would no longer recognise Loxia scotica has been deleted from BirdLife's Globally Threatened Bird Forums (Threatened European & Central Asian Birds):
http://www.birdlifeforums.org/Globally%20Threatened%20Bird%20Forums/Threatened%20European%20Birds/?14@108.JvdOa9AIcF9.0@

According to Birdwatch, "BirdLife has now said that the statement will not be official policy for the foreseeable future":
http://www.birdwatch.co.uk/website/content/view/2857/32

I suspect that there have been some interesting politics going on behind the scenes...

Richard

[njlarsen]

Birds actually seem more 'oversplit' than mammals, herps or insects.



Contra quote from Birdwatch: ... the biological species concept, upon which BirdLife itself bases its taxonomic decisions. In its application of this concept, BirdLife even “accepts that a considerable percentage of the global avifauna ... requires reassessment as a result of being ‘over lumped.’”

:eek!: o:D

Niels

[Mysticete]

Right now there is a tremendous amount of splitting within North American reptiles and amphibians, largely because the application of BSC really works poorly for many nonbird groups, which seems to support Njlarsen and my viewpoints. Just these past few weeks a paper had come out supporting splitting the Common Kingsnake into 4 species.

[jurek]

The policy of splitting every recognizable subspecies as a species was in place in 19. and early 20. centuries. It was ditched for several scientific and many practical reasons. Most of them remain valid now. Why to reinvent a wheel?
Maybe somebody should reprint some seminal ornithology work from ca. 100 years ago, when the number of bird species dropped from ca 20,000 to 8,000?

BirdLife International made decision many years ago to include only full species in their red list (and not subspecies, unlike eg. mammals, fish or plants). The reason stated was purely practical - monitoring and conserving the 1000+ threatened species would already be overwhelming task, and protecting every race could jeopardize the conservation of more distinctive species. Did the reasons change? Do mankind already protects well every bird species?

I, for one, would welcome BirdLife not to start splitting species, but simply include some or more distinctive subspecies in their Red List. This would: 1) save the cost and effort of re-naming and re-publishing the list, which changes nothing in the field conservation 2) avoid chaos during the transition, where ornithologists are in-process of splitting and debatting, often with the shaky understanding of the taxonomy. 3) maintain a clear priority of distinctive species over less distinctive races, if prioritizing the conservation resources was ever needed. 4) avoid the well-intentioned raising the form to the species to prioritize the conservation, which is now rather well-known trick and was criticized in the Economist (the case of Bornean Clouded Leopard and WWF campaign about Borneo rainforest). 5) bring birds to line with other organisms (where separate conservation status is given to subspecies, eg. Siberian Tiger, or even stocks and subpopulations, eg. Black Sea population of Beluga Sturgeon).

To put it short: I feel that ornithology is moving in circles.

[Mysticete]

I suspect this argument will go in circles until the sun supernovas, but...

I think that perhaps you grossly oversimply changes in taxonomy viewpoints within the last two centuries, nor do I believe they are completely driven by conservation in the vast majority of cases.

For one, the 19th century approach to taxonomy was rejected largely because it was way too typological, and failed to understand that individual variation was a major issue to consider in many cases. Add in the artifacts of the time (slow speed of communication, researchers having to do with dead and perhaps poorly preserved specimens, and lack of time to assess collections), and taxonomists tended to ascribe every new variation as a new species, hence twenty or so species of cassowaries for instance.

Early last century researchers tried to approach taxonomy in a more rigorous fashion and thus the biological species concept was formed. However in many cases this concept was misapplied, leading to lumping of just about anything that could hybridize, even if only rarely or only in captivity. In addition you had a lot of sweeping revisions of taxonomy, with little peer review in many cases, which led to mass lumping of species/ genera/etc with little and sometimes no actual evidence for the change. In fact, this is often times listed as a reason for "going back" to earlier ideas, at least in SAC and AOU checklist proposals.

Nowadays it's not that we have reverted to a 19th century taxonomic approach, but we simply have tools that earlier researchers couldn't have dreamed of. We can use molecules to test polyphyly and paraphyly of species, assess phylogeographic patterns, divergence dates, and hybridization. We have access to large collections of material to assess variation in morphology, not to mention morphometric approaches to quantify it. Researchers undergo complicated field experiments and study sonograms to assess reproductive barriers. In other words I believe the change in taxonomy is being driven by actual science, not just a shift in attitudes.

I no longer am a adherent to strict PSC bird classification, however if you look carefully you see that pure PSC splits are seldom well received by checklist committees or most major taxonomic bodies. Certainly the PSC splits in Tiger, Wolf, American Marten, etc have not been accepted by anyone, nor do I think it is likely unless more research is done to verify them. If you look at the most recent AOU checklist proposal (sorry if I have to keep falling back on the New World, but it's what I know best), all three splits are BSC splits. Pacific Wren and South Hills Crossbill both assortatively mate and do not recognize other forms as being conspecific. Even the dodgiest BSC split, the Scrub Jays, utilize different habitats and have a very narrow and small hybrid zone.

I personally don't feel as enough research has been done on old world crossbills, or even New World forms, to feel we are ready to split them quite yet. However if the different forms, or at least a few forms, do assortatively mate and inhabit different ecological niches, than they are good species under any definition we use.

[Richard Klim]

BirdLife International made decision many years ago to include only full species in their red list...
And I suspect that BLI has always been somewhat sceptical of the validity and conservation value of Scottish Crossbill, given that it has long classified it as one of only four 'Data Deficient' species occurring anywhere in the Palearctic region. It's quite remarkable that a locally-common and much-studied endemic (and local conservation flagship species), inhabiting a major tourism region (which is also one of the most popular birding areas in Europe), still has the same threat assessment status as Vaurie's Nightjar and Sillem's Mountain Finch!

Richard

[bombycilla]

I suspect that there have been some interesting politics going on behind the scenes...

Richard

I suggested earlier that RSPB would not be happy about this, and clearly ( and rightly) they were not !

However, part of the reasoning for this shift in policy by their partner may be that a recent RSPB survey estimated 13,000 Scottish Crossbills in Scotland and it has subsequently been dropped from their own Red List recently, which doesn't sit well for an 'endangered' species. This hardly suggests that they are scarce or even data deficient, though I personally do think more study is needed.

The BOU is who we (in UK) should be concerned with regarding the classification and status of this particular 'species' and there is little chance that scotica will be demoted to subspecies by them: as has been debated on here before, a sub species of what exactly ?

[chris butterworth]

The real problem lies with the ever thorny problem of " What is a species". While ornithology continues to stick with BSC there will always be more than enough contention. As PSC gives a "truer" ( note the way I've said that ! ) picture of biological diversity and is scientifically "provable", barring human error, then isn't it time to take it on board, finally. I will admit that it will leave those in the field with a lot of BIIK's ( buggered if I know's ) but taxonomy is a scientific disipline, not a fluffy little security blanket for birders. Here endeth my latest rant!!
Chris

[njlarsen]

If I understand the PSC correctly, then every true subspecies would become a full species. Let us look at the situation in White-winged Dove: it used to have two subspecies in the US, an eastern on in Texas, and a more western one in NM, as far as I know. Then the human induced habitat changes led to range expansion into northern Texas of both populations where they inter breed freely. So not so long ago, PSC would have led to the conclusion that they were full species, but the current situation is that they are one interbreeding population where the two classical subspecies probably will end up being the extremes of a continuum.

For that reason, I don't think that PSC necessarily gives a truer picture of biological diversity.

Niels

[Mysticete]

The big problem with PSC however is where do you make the "cut off" for what is a new species? Taken to an extreme every clade is it's own species, regardless of how distinct it is. That is why I think it should be tempered with application of BSC. PSC might be more useful for species where reproductive isolation is REALLY hard to assess (i.e. snakes), but for most birds this isn't an issue.

[Daniel Philippe]

That is why I think it should be tempered with application of BSC.

But it also depends on who applies the concept. For most authors the Island Thrush is 1 species, but could be up to 31 under this concept : http://specify5.specifysoftware.org/Informatics/bios/biostownpeterson/P_KU_2007.pdf

[birdboybowley]

But it also depends on who applies the concept. For most authors the Island Thrush is 1 species, but could be up to 31 under this concept : http://specify5.specifysoftware.org/Informatics/bios/biostownpeterson/P_KU_2007.pdf

Now there's a bird that needs sorting out!!!

[njlarsen]

But it also depends on who applies the concept. For most authors the Island Thrush is 1 species, but could be up to 31 under this concept : http://specify5.specifysoftware.org/Informatics/bios/biostownpeterson/P_KU_2007.pdf

His abstract even says that the 31 would be recognizable under the biological species concept ...

Niels

[thyoloalethe]

His abstract even says that the 31 would be recognizable under the biological species concept ...

Niels

While I think Turdus poliocephalus should probably be split into several species, I find the recognition of 31 at this stage to be a tad too high. He recognizes 2 species on Sumatra and 3 on Java. I'm not aware of any group of species that shows this level of speciation in this region (then again, maybe some of the species there are overlumped). The plumage differences between them seem to be relatively minor, e.g. the north Sumatran T.p. loeseri is in the "blackish above, orange below" category, whereas the south Sumatran T.p. indrapurae falls in the "blackish above, brick red below" phenotype. The Javan races fall into similar plumage types as well, and I think all Sumatran and Javan forms could continue to be considered as one species, at least for now.

Similarly, he splits T.p. placens from the Banks Islands from the rest of the North Vanuatu/Santa Cruz races. He notes the plumage differences between them but states that "these differences are not particularly striking." I don't think as strong a case can be made for its separation as for the highly distinctive T.p. albiceps to the south.

[fugl]

Since the discussion seems to have shifted from crossbills to speciation in general, what about measures of “genetic distance” between related populations? Where do these fit in? Can “genetic distance” (not obviously correlated with any other ascertainable differences between the populations) be legitimately regarded as just another criterion under the PSC or must it be seen as the basis of something new—the “GSC”?

How reliably (cheaply?) can “genetic distance” be measured at the moment?

[Mysticete]

With the caveat that I am not a geneticist:

Genetic distance is useful, but is relative and can't really be used as and independent scale, since some groups do seem to evolve faster than others, and so might accumulate genetic differences faster. It's probably useful, for say comparing a single family of continental birds, but probably not useful otherwise.

AFAIK someone did publish a classification scheme based solely on genetic distance (I have the paper...somewhere). However you get hilarious results like recognizing Drosophila as a linnean order, while most bird families would be reduced to one species, or something like that.

[fugl]

With the caveat that I am not a geneticist:

Genetic distance is useful, but is relative and can't really be used as and independent scale, since some groups do seem to evolve faster than others, and so might accumulate genetic differences faster. It's probably useful, for say comparing a single family of continental birds, but probably not useful otherwise.

AFAIK someone did publish a classification scheme based solely on genetic distance (I have the paper...somewhere). However you get hilarious results like recognizing Drosophila as a linnean order, while most bird families would be reduced to one species, or something like that.

Thanks, very interesting. Fascinating that about the fruit flies which now that you recall it to my mind I remember seeing something about not too long ago.

[jpoyner]

Recent trapping has revealed some very surprising results indeed! ;)

By the way, what's happened to the original link about all this. Can't seem to find anything now on the BI website??

[Richard Klim]

Funny, the link to the original statement seems to no longer work and I can't find any other online reference to this at all now?
That's right - it's been deleted - see post #45 (including the Birdwatch news item).

Richard

[chris butterworth]

EEK! I seem to have opened a can of worms here. While I stand by my post that PSC is, scientifically, more useful at delineating species in regard to their common descent, I was not advocating the complete abandonment of methodologies used within BSC. Both concepts have their benifits, it's just that PSC relies less on personal choice ( except for where to draw the line at what constitutes a "species") I, personally would "dump" the species and introduce the term taxon for all diagnostibly distinct ........ erm! "thingies".
Chris

[Melanie]

That is really strange that the Loxia scotia thread has disappeared in the BirdLife forum. It is normaly not the case that Birdlife delete forum entries. But fortunately here is the original text:

http://www.birdforum.net/showpost.php?p=1599064&postcount=1148

Hmm, the plot thickens.

The post stating that BirdLife would no longer recognise Loxia scotica has been deleted from BirdLife's Globally Threatened Bird Forums (Threatened European & Central Asian Birds):
http://www.birdlifeforums.org/Globally%20Threatened%20Bird%20Forums/Threatened%20European%20Birds/?14@108.JvdOa9AIcF9.0@

According to Birdwatch, "BirdLife has now said that the statement will not be official policy for the foreseeable future":
http://www.birdwatch.co.uk/website/content/view/2857/32

I suspect that there have been some interesting politics going on behind the scenes...

Richard

[jpoyner]

Strange indeed. It would be interesting to know exactly what was the reason behind its original publication and why the backtrack. All this does not seem very professional or scientific to me. Just what is going on behind the scenes?

[jurek]

I can understand that birdlife doesn't want to get entangled into politcal and heated discussion.

On the PSC, you have similar problems with delineating 'what is independent population'. Actualy, even more problems, because numver of forms is several times larger so more borderline cases.

About genetic distance: it is highly variable between groups. There are groups very distinct genetically, and groups which 'exploded' recently and have little genetic variation.

One useful thing is, however, that it allows to measure gene flow (or lack of it).

[Russlac123]

If Scottish Crossbill is split by the BOU based on these criteria, would it not be consistent to also split Atlas, Balearic, Corsican, Balkans, Cyprus and several other "Red Crossbill" subspecies?

[chris butterworth]

If Scottish Crossbill is split by the BOU based on these criteria, would it not be consistent to also split Atlas, Balearic, Corsican, Balkans, Cyprus and several other "Red Crossbill" subspecies?

No reason, whatsoever, but the BOU only concerns itself with the British List when it comes to taxonomy and nomenclature.
Chris