Crossbills (1 Viewer)

jurek said:

Some morphs show different behaviors (see pepper moths perching on different trees) and can mate assortatively (eg feral pigeon morphs). So it suits.

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Different morphs of Buteo buteo show differing behaviours and they mate assortively (sort of)

Any links to more info martinf?

Mmmm, classification of Crossbills to "types" / species/ subspecies. How do we do this - biometrics or calls or, shock horror, behavioural data. A combination of all these ? I hate to say it but due to overlap in biometrics and morphology within the (vocal) "types" the only way is DNA analysis and even then I am not sure we "are there yet" with crossbills.

It might be worth reading the bios listed in post #32 which are summarised from the South Hills paper - total overlap in bios between types. This would mean that we could only safely classify crossbills (on bios) by taking those exactly on the mean points, plus any safe variance either side that does not conflict with the other 'types' - not gonna happen....often This is typical for crossbill vocal types in that there is usually an overlap between types, sometimes caused by a bill depth range of up to 2.0 mm difference (within a vocal type), which is MASSIVE in crossbills terms - a recent Spanish paper was trying to split crossbill types on fractions of a millimetre !. So, in South Hills study a bird that is presumed to be of a praticular type is classified on call type primarily if it lies in the overlap zone ?

I know that in the wild crossbills 'morph' their calls. I have trapped, ringed and released Common Crossbills and the same individuals have given up to 3 different call types as they flew off. This may be rare, but it happens. A male bird released in January flew to a tree and continued calling. Its mate flew in with a different call. When the two flew off the male had 'synced' his flight call to that of the female. Crossbills can adapt or change their calls. This pair successfully nested nearby.

IMO calls are better at classification than bios for two reasons:

1) They are 'cultural', whether learned or not. What the bird "thinks" it is is still important, even if it is not what it thinks it is.

2) They can be identified from recordings without the need for bios - even by "birders" as opposed to parabola wielding "ornithologists ! We can classify them but it doesn't mean we are correct in our classification, just that we can be consistent in our classification and it is repeatable.


My advice kids, stay away from Loxia, they will phuk you up quicker than a crystal meth habit -take up Fly Fishing for trout, much more rewarding and a better use of time. :eek!:

Lynryd Cynryd

Mysticete said:

except that morphs applies random morphological variation (see the use of color morphs in snakes, etc). Whereas these different morphs seem specialized for certain foods and for the most part breed assortatively. So I wouldn't call a morph a proper name either. Our current taxonomy doesn't really accommodate Crossbills and similar seed eating birds.

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Another example better suited to integrative taxonomy?
MJB

Parrot Crossbill

OK, forgive me if this is a stupid question, I have problems getting to grips with this crossbill mess. Let's say these crossbills aren't true species in the present concept. Then what makes Parrot Crossbill a species and not yet another call type? What are the arguments for not elevating, say, South Hills Crossbill to species level and still keep Parrot?

gusasp said:

OK, forgive me if this is a stupid question, I have problems getting to grips with this crossbill mess. Let's say these crossbills aren't true species in the present concept. Then what makes Parrot Crossbill a species and not yet another call type? What are the arguments for not elevating, say, South Hills Crossbill to species level and still keep Parrot?

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It is morphologically different from other crossbills - much bigger, with a bigger and deeper bill structure. They breed with each other esp. where you live in Sweden - a Parrot xbill female will not mate with a Common Crossbill male as it will not be able to feed himself, her on the nest and the clutch when they hatch. Not saying they never cross breed but presumably not enough to cause hybrids. However, here is Scotland there are intermediates between Common and Parrot ( currently called Scottish Crossbills) and even intermediates between Scottish and Parrot.

In Sweden, easy Parrots and Commons !

jurek--You seem pretty confident about the crossbill system and the idea of applying morphs. You say Types are likely a temporary thing that merge or die-off quickly? what is this based on? Here in the States, flight calls seem quite stable. Groth had birds for years and he mixed them in cages with other call types and exposed them to several call types in the wild, and none of the birds changed calls. I also know this because I've personally gone through all or nearly all of Groth's collection.

crossbill7 said:

jurek--You seem pretty confident about the crossbill system and the idea of applying morphs. You say Types are likely a temporary thing that merge or die-off quickly? what is this based on?

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Myself and Jurek haven't always agreed on all things crossbills but I have to say in Europe these 'types' may be much more 'dynamic' than over in the States. It seems even Scottish Crossbill calls have 'evolved' over the last 40 years, and there is a distinct possibility there is more than one Crossbill endemic to Scotland, if we base our assessment on vocalizations. In Europe, so far, there are two modal sizes of bill depth for Common Crossbill (plus the usual spread in the overlap zones) yet there are more and more call types appearing/being discovered. There has been a lot of work done in the States, most of it pioneering, and there have been quite a lot of key workers. In Europe we are a bit behind in that very few people are interested in crossbills and even then most are in the UK.

It all depends on how we categorize a type, on calls or biometrics/ environmental factors. Based on the DNA evidence over here, there must be significant gene flow between crossbills, just wish they could refine the analysis of the genes a bit more.

crossbill7 said:

jurek--You seem pretty confident about the crossbill system and the idea of applying morphs. You say Types are likely a temporary thing that merge or die-off quickly? what is this based on? Here in the States, flight calls seem quite stable. Groth had birds for years and he mixed them in cages with other call types and exposed them to several call types in the wild, and none of the birds changed calls. I also know this because I've personally gone through all or nearly all of Groth's collection.

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I told shortly before.

Null hypothesis is that call types are simply morphs, and it is up to crossbill researchers to prove otherwise.

Stable flight calls for several years are meaningless to discussion about subspecies or species - one needs to observe stability over much longer time scale.

Genetic variation between morphs is non-existent or tiny. I appreciate, that future, more detailed genetic studies, might yet to find subtle genetic markers. But if they exist, they are tiny - not within the level expected if there was really long-term isolation.

Several publications proposed a scenario that, as conifer cones are very uniform food source, small bill differences cause very different foraging efficency, and very quick selection of bill size most suitable to a particular conifer. Proof are bill morphs evolved in very recently isolated mountain ranges in North America. This scenario implies that reverse evolution will be equally quick - as conifer aviability changes, the population will very quickly evolve back and cease to be different from others.

The lack of genetic difference supports the scenario of reverse selection and disappearance of partcular morphs, possibly repeatedly over evolution of Loxia. Different conifer species exist for much longer than genus Loxia, so there was ample time to create bigger genetic differences - but they aren't.

It also explains why in Northern Europe, where exist only two common conifer species - Norway spruce Picea abies and Scots Pine Pinus sylvestris - developed stable bimodal distribution of bill sizes of Common Crossbill Loxia curvirostra and Parrot Crossbill Loxia pytyopsittacus.

Jurek,

Good points, the onus is on crossbill researchers.

To me the single key conifer concept here in the states has been overplayed.....as a result oversimplifying the crossbill system. From what I've researched, many types also show differences in migration patterns, differences in core zones of occurrence (home ranges in a sense), differences in flight call vocalizations, and small differences in morphology and ecological associations. If each type was looked at from the perspective of how they __actually__ act throughout the year (yes, a very difficult task for a crossbill researcher for sure), we'd be further ahead.


Additionally, I will say at least here in the states, in Rodd Kelsey's dissertation (it might even be cited in one of Sewall's papers that I mentioned here in this post yesterday), he addresses a blind audio test between types 2, 3, 4, and 5 ---these were the sympatric types found in his/hers studies --they were ID by 3-4 people with 100% accuracy I believe (or close to 100%). The flight calls are very diagnostic, much more than excitement calls IMO.

I guess you're in the camp that redpolls are one species?

I would also echo bombycilla, that within Common/Red/Scottish Crossbill, the whole basis of discussion - different morphs of calls and bill sizes - is far from clear thing.

First, there is a question of how reliable and repeatable are measurements of 1-2mm of living bird, and how subjective is assigning sonograms into types.

Second, there exist subtle average differences, but there exist also intermediate calls, intermediate callers and intermediate bill sizes. And what to do with these intermediate birds?

They are likely birds not belonging to any morph, or switching between morphs. So crossbill call types are not discrete units (A, B, C...), but there is in fact a continuum of variation with several peaks of most common types.

Oops, Crossbill 7 you adressed a first part of my post in the meantime.

I don't know enough about Redpolls to form opinions.

jurek -- I agree with your assessment in many ways, but you sound quite sure of yourself as if the system deserves little attention. Have you actually read any of the papers. Things might also be quite different here in the States. I have always felt that Types across the pond have been split way too much....and that Types here in the States are easily identified via sonagram. To me, people haven't applied the same approach/scale that Groth used. As far as I'm concerned, everyone should be using the same scale that Groth used when ID-ing sonagrams........some of this is b/c papers charge for space, so crossbill researchers (some, not all) sometimes publish sonagrams that are so small that you essentially lose the diagnostic features.

FWIW: redpolls show no fixed genetic differences. Crossbills are most closely related to redpolls.

I would also like to point out that Jurek has over and over argued against the PSC, but in this case is arguing we should apply it to crossbills, since degree of genetic differentation is not the deciding factor in BSC

Eurotrash

crossbill7 said:

I have always felt that Types across the pond have been split way too much....and that Types here in the States are easily identified via sonagram.

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Splitting way too much ? I have to disagree M, it is not "us" claiming 10 vocal call "types" for Red Crossbill afterall is it ! As a crossbill vocalisation researcher I have always been clear that, for example, regarding Fc1 which is essentially an \/\ shape and which seems to be the call with most variations, that I for one 'lump' them together. I may describe and note the differences but I do not sub classify them eg. one of my "choopy" fc1's is lumped with a "British" fc1.

crossbill7 said:

To me, people haven't applied the same approach/scale that Groth used. As far as I'm concerned, everyone should be using the same scale that Groth used when ID-ing sonagrams........some of this is b/c papers charge for space, so crossbill researchers (some, not all) sometimes publish sonagrams that are so small that you essentially lose the diagnostic features

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I can understand that it may be in the interests of American Crossbill researchers to use the same methodology and classification set out by Groth but I don't see why we European researchers should feel obliged to follow it. I for one am not daft on his 'broadband' spectograms in his monograph on Crossbills which I understand were produduced on a Kay Sonograph !

Maybe we (Euros) should all have used the scale of those sonograms produced by Magnus Robb in Dutch Birding, but as I recall these were very small. I produce mine to correspond with the RSPB data from the 1990s as that is what I reference to the most. At 0.2 ms I can see all the resolution I need, and any any case my diagnostics are made primarily by ear, as some calls may look a bit different on sonagram but essentially sound (and are) the same.

Cheers,

L

Mysticete said:

I would also like to point out that Jurek has over and over argued against the PSC, but in this case is arguing we should apply it to crossbills, since degree of genetic differentation is not the deciding factor in BSC

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Just to clarify - I don't support species rank of Red/Common/Scottish crossbill call types under any concept.

Maybe you refer to my remark about Common and Parrot Crossbill Loxia 'curvirostra' and 'pytyopsittacus' in Scandinavia. It is indeed curious that they show no genetic difference. For the time being, I would keep the view of last 20 years, that they are very similar but separate species.

What is the current thinking on the Red Crossbill population on the Dalat Plateau, Vietnam?

bombycilla,

Good points and well taken!

Aren't there nearly as many Types being described across the pond? 7-9 depending on which classification system used. Have others even hinted at more splits too? I know "typing" crossbills is newer in Europe, and that certainly plays its part too....it's evolving. There's also been two different classification systems, which makes it a bit messy too. THen add that some in Spain want to split Types based on mm in morphology. I guess my overall point was, Groth described the types (8) in 1993, and since this time it's been a pretty stable system with 2 more types added. Type 9 South Hills birds (which he wouldn't have known about anyway), and the split of Type 10 from Type 4.

As for the looks of Groth's specs, I believe they are too clean...I'm not a fan of them based on looks....BUT, he used a good sized scale, which has not always been the case both here in States and across the pond. I see specs that are, at times, way too small IMO.

In short, I think there should be a standardized spec used for crossbill identification...one that is of sufficient size (closer to what Benkman and Groth have used)....that way everyone can get familiar with them. Summers' specs are a bit small for my liking, but I've certainly seen much smaller specs that are of little use IMO.

meridionalis

viator said:

What is the current thinking on the Red Crossbill population on the Dalat Plateau, Vietnam?

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Clement 2010 (HBW 15):

meridionalis [Robinson & Kloss, 1919] is large-billed, smaller than nominate, male head and body deep blood-red or rich scarlet, upperparts mottled or streaked darker, wings and tail uniformly dark brown.

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And allopatric with respect to any other 'subspecies'.