Crossbills (5 Viewers)

[JustinJansen]

Why John are call types not ok? This is a fact, however, it is difficult to understand according to our knowledge now. This winter I will be again in the forests here in Holland to try to understand a bit more.... See for example this table and this, but remember it is work in progress.....

 

[Farnboro John]

Why John are call types not ok? This is a fact, however, it is difficult to understand according to our knowledge now. This winter I will be again in the forests here in Holland to try to understand a bit more.... See for example this table and this, but remember it is work in progress.....

Because they are no different to the identifiable, separable and consistent local dialects of Great Tits and Chaffinches. They are completely meaningless.

Sorry. Glib.

Inferences are being drawn about speciation in Crossbills, from call types. However, other species of birds also have geographically consistent, separable, identifiable dialects without any suggestion that they are other than single species. My view is therefore that no inferences should be drawn from Crossbill call types: and so far other evidence is lacking.

John

 

[Ben Wielstra]

Well it's not that evidence is lacking, it's just that it doesn't tell the story that some people prefer.

I guess there is an upper limit of 26 species, or will there be type AA, AB etc?

 

[l_raty]

Call types are learned.
Birds fostered by parents giving another call type than their biological parents end up calling like their foster parents.
There is also at least one well documented case of a bird that changed its call to match the call type of the population that it had entered. Although this type of change has (AFAIK) never been observed in captivity and is presumed to be rare, in practice it took two years for it to happen, and it is certainly not something easy to record in the wild. Also, one of the most important functions of crossbill calls is for communication within the flock during foraging, and it's unclear to which extent this type of social interactions are reproduced in captivity: what happens to calls in captivity might quite easily not be representative of what happens in the wild, I think. Anyway, whatever the frequency, the simple fact that this can happen runs strongly against call type as such being a taxonomically significant character, in my opinion.

 

[stoned curlew]

Well it's not that evidence is lacking, it's just that it doesn't tell the story that some people prefer.

I guess there is an upper limit of 26 species, or will there be type AA, AB etc?

Yes, there is lots of evidence showing that there are many different call types, but there is still little evidence to show that these 'call types' are reproductively isolated taxa.

 

[Ben Wielstra]

I would say there is evidence that they are not reproductively isolated taxa!

 

[Nutcracker]

I'd suspect they are 'semi-isolated' - much like different languages ("call types"!) in Homo sapiens - ~95% of English speakers mate with other English speakers, ~95% of French speakers mate with other French speakers, ~95% of Dutch speakers mate with other Dutch speakers, and so on, but there is enough gene flow in the small % that do mate across call types to limit any substantial differentiation over time.

 

[Richard Klim]

'rubrifasciata'

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

[Dutch summary]​

... 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. ...

Forthcoming...

Hinchon 2014. Two-barred Crossbill or 'rubrifasciata' Red Crossbill at Farnham Heath, England, in March 2014. Dutch Birding 36(5): 330–331.

[With thanks to Alain Fossé for reporting on AvianReferences.]

 

[Zephyrus Carrington]

Because they are no different to the identifiable, separable and consistent local dialects of Great Tits and Chaffinches. They are completely meaningless.

Sorry. Glib.

Inferences are being drawn about speciation in Crossbills, from call types. However, other species of birds also have geographically consistent, separable, identifiable dialects without any suggestion that they are other than single species. My view is therefore that no inferences should be drawn from Crossbill call types: and so far other evidence is lacking.

John

As I understand it, different crossbill call types co-exist in the same place, and seem to be reproductively isolated from each other, which is rather different from the examples you give.

 

[Richard Klim]

'rubrifasciata'

Hinchon 2014. Two-barred Crossbill or 'rubrifasciata' Red Crossbill at Farnham Heath, England, in March 2014. Dutch Birding 36(5): 330–331.

A short note (with four photos) concluding that the adult male concerned represents 'rubrifasciata' rather than bifasciata. Kees Roselaar comments similarly.

 

[bombycilla]

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

Your views and arguments are just too simplistic I am afraid. You assume variations in crossbill call structures are "dialects" - why ? You also assume that Crossbills hear other crossbill calls as we do. Where is your evidence for this ? The call a crossbill emits is often in relation to the context the bird finds itself in, whether alarm (varies depending on predator), 'excitement' call, flight call (single and as part of a group), feeding calls, pre flight calls, flying to and from the nest etc etc.

I can assure you even though I am somewhat rusty due to an on going dearth of crossbills in NE Scotland I can still differentiate the various crossbill calls by ear and would wager Magnus Robb can too ! Perhaps we musicians are blessed with perceptive hearing ? However, my position is that if I can do it so can someone else.

Anyone that knows me and the research I have undertaken over the last decade knows that I do not conform to the accepted commonly held views/current conclusions regarding loxia sp - impressive as it is I don't particularly like arms races with squirrels and cones, multi variate analyses that biometrically differentiate crossbill types and I agree that there is too much splitting done on calls that are clearly 'variants'. However, not all call type classifications are variants of a single call type (as you seem to assume) and if you studied them you would see this ! However, there is plenty stuff out there that taxonomically describes bios with call types, including Scottish. But....there is overlap and therein lies the problem with Loxia. If you are looking for clearly defined, distinct parameters for Loxia taxonomy then I honestly don't think you will never be happy as it won't happen.

Crossbills, and their various types (species if you want), appear to be in constant state of flux, possibly due to environmental factors, variation in food sources etc. The fact that crossbills giving a single call type can have as much as 2.0mm variation in bill depth perhaps explains why there is gene flow between the various 'types' and hence DNA results are blurry. This, combined with the possibility that calls are 'cultural' as well as biological = crossbill 'soup'. Personally I hold call type a better diagnostic even above biometrics - that 2mm variation in bill depth that Edelar had with a single type is then easier to manage. Why do crossbills have such variation in bill structure within a type ? To ensure the 'type' survives I guess, as individuals will select for overlapping food sources in the event of a 'famine' period of the main one (see below re-Scotland).

To the Scottish question. Last Scottish I had were a flock of 20 in November 2012 at Braemar. Parrots have also not bred in any numbers in Deeside in 2013 and again this year. It will be interesting to see "what" crossbill bounces back from this localised year zero in Deeside. These events seem to happen every 20 or so years from what I can see, also described in Speyside by DNT and from old NESBR records. It is now fairly evident that many of the birds that DNT and Alan Knox referred to as "Scottish Crossbill" are in fact what we today call "Parrot Crossbill" here in Scotland. Alan's recordings of visually ID'd "Scottish" are a mix of Parrot and some Common calls by today's nomenclature (which is backed by pretty robust biometric data, something that both pioneers lacked). However, Parrot Crossbill is the only real candidate for being the relict Caledonian species - an isolated population of Parrot Crossbill. In this respect both gentlemen were possibly correct in their diagnosis. The assumption that "Scottish" crossbill would be biometrically 'intermediate' to Parrot and Common is the factor that has muddied the water imo, coupled with the fact that Parrots also have as much as 2mm variation in bill depth. Modern "Scottish", the intermediate form, would appear to be a relative newcomer, possibly a type of Common that is sedentary, or a sub type of Parrot; a hybrid just seems to convenient though it is possible. There are no "Scottish" 3C calls in Alan's recordings from the 70's onwards and DNT's recordings are inconclusive.

So, to call it all "completely useless rubbish" from the bastion of your arm chair really is an insult to all the professional and, like me, keen amateur ornithologists who have dedicated large parts of their lives attempting to try and understand these fascinating and challenging finches.

But we are used to it.

Lindsay

 

[Nutcracker]

Interesting info, thanks!

Modern "Scottish", the intermediate form, would appear to be a relative newcomer, possibly a type of Common that is sedentary, or a sub type of Parrot; a hybrid just seems to convenient though it is possible. There are no "Scottish" 3C calls in Alan's recordings from the 70's onwards and DNT's recordings are inconclusive.

So presumably therefore, they can't be identified with Hartert's definitive 1904 specimen, and thus, can't properly be called Loxia scotica? Sorry, but that is the only conclusion I can reach, and that name must therefore be dropped from use. If these "Modern Scottish" birds are distinct, they need a new name, separate from Hartert's. Is Hartert's specimen better placed in synonymy with L. pityopsittacus, or with L. curvirostra?

 

[lewis20126]

Interesting info, thanks!

So presumably therefore, they can't be identified with Hartert's definitive 1904 specimen, and thus, can't properly be called Loxia scotica? Sorry, but that is the only conclusion I can reach, and that name must therefore be dropped from use. If these "Modern Scottish" birds are distinct, they need a new name, separate from Hartert's. Is Hartert's specimen better placed in synonymy with L. pityopsittacus, or with L. curvirostra?

I've not seen a photo of the specimen but it will be a brave man who submits the paper to Ibis suggesting (demonstrating?) that scotica is a synonym of one of the other forms. Given that call cannot be determined from the specimen, DNA is useless and the plumages overlap entirely, presumably all you would have would be bill morphology. If the measurements of the type sit anywhere within the range of the other two taxa, then it's bye bye L scotica? Maybe.

cheers, alan

 

[Farnboro John]

Your views and arguments are just too simplistic I am afraid. You assume variations in crossbill call structures are "dialects" - why ? You also assume that Crossbills hear other crossbill calls as we do. Where is your evidence for this ? The call a crossbill emits is often in relation to the context the bird finds itself in, whether alarm (varies depending on predator), 'excitement' call, flight call (single and as part of a group), feeding calls, pre flight calls, flying to and from the nest etc etc.

I can assure you even though I am somewhat rusty due to an on going dearth of crossbills in NE Scotland I can still differentiate the various crossbill calls by ear and would wager Magnus Robb can too ! Perhaps we musicians are blessed with perceptive hearing ? However, my position is that if I can do it so can someone else.

Anyone that knows me and the research I have undertaken over the last decade knows that I do not conform to the accepted commonly held views/current conclusions regarding loxia sp - impressive as it is I don't particularly like arms races with squirrels and cones, multi variate analyses that biometrically differentiate crossbill types and I agree that there is too much splitting done on calls that are clearly 'variants'. However, not all call type classifications are variants of a single call type (as you seem to assume) and if you studied them you would see this ! However, there is plenty stuff out there that taxonomically describes bios with call types, including Scottish. But....there is overlap and therein lies the problem with Loxia. If you are looking for clearly defined, distinct parameters for Loxia taxonomy then I honestly don't think you will never be happy as it won't happen.

Crossbills, and their various types (species if you want), appear to be in constant state of flux, possibly due to environmental factors, variation in food sources etc. The fact that crossbills giving a single call type can have as much as 2.0mm variation in bill depth perhaps explains why there is gene flow between the various 'types' and hence DNA results are blurry. This, combined with the possibility that calls are 'cultural' as well as biological = crossbill 'soup'. Personally I hold call type a better diagnostic even above biometrics - that 2mm variation in bill depth that Edelar had with a single type is then easier to manage. Why do crossbills have such variation in bill structure within a type ? To ensure the 'type' survives I guess, as individuals will select for overlapping food sources in the event of a 'famine' period of the main one (see below re-Scotland).

To the Scottish question. Last Scottish I had were a flock of 20 in November 2012 at Braemar. Parrots have also not bred in any numbers in Deeside in 2013 and again this year. It will be interesting to see "what" crossbill bounces back from this localised year zero in Deeside. These events seem to happen every 20 or so years from what I can see, also described in Speyside by DNT and from old NESBR records. It is now fairly evident that many of the birds that DNT and Alan Knox referred to as "Scottish Crossbill" are in fact what we today call "Parrot Crossbill" here in Scotland. Alan's recordings of visually ID'd "Scottish" are a mix of Parrot and some Common calls by today's nomenclature (which is backed by pretty robust biometric data, something that both pioneers lacked). However, Parrot Crossbill is the only real candidate for being the relict Caledonian species - an isolated population of Parrot Crossbill. In this respect both gentlemen were possibly correct in their diagnosis. The assumption that "Scottish" crossbill would be biometrically 'intermediate' to Parrot and Common is the factor that has muddied the water imo, coupled with the fact that Parrots also have as much as 2mm variation in bill depth. Modern "Scottish", the intermediate form, would appear to be a relative newcomer, possibly a type of Common that is sedentary, or a sub type of Parrot; a hybrid just seems to convenient though it is possible. There are no "Scottish" 3C calls in Alan's recordings from the 70's onwards and DNT's recordings are inconclusive.

So, to call it all "completely useless rubbish" from the bastion of your arm chair really is an insult to all the professional and, like me, keen amateur ornithologists who have dedicated large parts of their lives attempting to try and understand these fascinating and challenging finches.

But we are used to it.

Lindsay

I absolutely refute the suggestion that your research (and for that matter your musician's ear, which sadly I do not possess) is completely useless rubbish. It is as useful as that of the people who have determined that Great Tits and Chaffinches have dialects.

That is not what I was saying. What I was saying was that the different calls being heard cannot be reliably connected to either genotypes or phenotypes. In a nomadic species like Crossbill - which although it exhibits season-driven migratory behaviour also exhibits food-related irruptive behaviour which can be coupled with what amounts to irregular local extinction, or lacuna generation if you prefer, obviously dialect in the regional sense that we understand it is unlikely.

Which raises the question of what the different call types mean. Since they don't correspond to phenotypes, genotypes or geographic locations, and since the phenotypes show wide variation, what more likely than that Crossbill voices are just that - voice variations as wide as the difference between Paul Robeson and Joe Pasquale. Not even a dialect or accent - just a voice.

Which leads me to what I did mean: the hypotheses about Crossbill species as related to Crossbill voices are complete rubbish. A new hypothesis is required that actually deals with the present evidence (or lack thereof.)

John

 

[Richard Klim]

Scottish Crossbill

Is Hartert's specimen better placed in synonymy with L. pityopsittacus, or with L. curvirostra?

Hartert described scotica as a ssp of L curvirostra, but see also Vaurie 1956 (p25–26).

 

[Nutcracker]

Given that call cannot be determined from the specimen, DNA is useless and the plumages overlap entirely, presumably all you would have would be bill morphology. If the measurements of the type sit anywhere within the range of the other two taxa, then it's bye bye L scotica? Maybe.

cheers, alan

I'd say not just 'maybe', but 'definitely', on clear nomenclatural grounds.

Hartert described it as a ssp of L curvirostra, but see also Vaurie 1956 (p25–26).

Thanks! Until earlier today I'd have said under pityopsittacus thinking back to the obvious thick-billed pinewood birds in Scotland. But Lindsay's clear point "It is now fairly evident that many of the birds that DNT and Alan Knox referred to as "Scottish Crossbill" are in fact what we today call "Parrot Crossbill" here in Scotland" — the really thick-billed birds one sees in Scotland are not, and never have been, "Scottish Crossbills". I've not seen Hartert's specimen either, but it obviously needs re-examination in light of the new data.

I'll finish with a couple of field sketches I made of birds in two flocks of crossbills I saw a day apart a few years ago. One flock was feeding in pines, the other feeding in spruce. What do people think they are?

 

[l_raty]

Thanks! Until earlier today I'd have said under pityopsittacus thinking back to the obvious thick-billed pinewood birds in Scotland. But Lindsay's clear point "It is now fairly evident that many of the birds that DNT and Alan Knox referred to as "Scottish Crossbill" are in fact what we today call "Parrot Crossbill" here in Scotland" — the really thick-billed birds one sees in Scotland are not, and never have been, "Scottish Crossbills". I've not seen Hartert's specimen either, but it obviously needs re-examination in light of the new data.

Hartert's description (Die Vögel der paläarktischen Fauna) is here. The following are among the measurements he gave there ("anglica" from England and "hispana" from Spain nowadays synonymized with nominate curvirostra):

Wing length:

L. c. curvirostra male: 99—102 (fem. 94—97.5)
L. c. anglica: 99—102.5
L. c. hispana: ?
L. c. scotica: 100—104
L. pytyopsittacus male: 104—108​

Bill length:

L. c. curvirostra male: 18—20
L. c. anglica male: 17.5—19
L. c. hispana male: 21
L. c. scotica: about 19
L. pytyopsittacus male: 19—20(21)​

Depth of upper mandible at the base:

L. c. curvirostra male: 7.2—8.2
L. c. anglica male: about 8.2
L. c. hispana male: "not quite" 7
L. c. scotica: 8.2—8.6
L. pytyopsittacus male: 9—10​

Breath of lower mandible at the base:

L. c. curvirostra male: 10.8—11.4
L. c. anglica male: 12—12.8
L. c. hispana male: 11
L. c. scotica: 12.5—13.6
L. pytyopsittacus male: 13—16​

This indeed seems to make scotica (from/at the beginning) intermediate between curvirostra (incl. "anglica" and "hispana") and pytyopsittacus. (All measurements overlap with both, except the height of upper mandible for which the range of variation in scotica just touches the upper limit of the variation in curvirostra, but doesn't reach the lower limit of the variation in pytyopsittacus. I'd have preferred to see the sample sizes, though... It's also a bit unfortunate that he gave no comparable measurements for southern larger-billed birds.)
Note that many of the birds he saw may have been collected significantly earlier than 1904. The designated type of scotica is from 1870.

But I will reiterate my earlier suggestion... All apparently started with a pine-adapted crossbill population with medium-large bill, presumably in equilibrium with its environment, where the only conifers were Caledonian pines—a situation that obviously doesn't exist any more, as a lot of exotic conifers have been planted all around Scotland. Crossbills, as I see them, are quite opportunistic birds—they will go where they find easy food, and "where they find easy food" depends directly on their individual bill size. Here, the birds that would have had the best reasons to leave the pine forests and colonize the new plantations, are those with a bill smaller than average—those to which it was hardest to open a thick pine cone, and particularly easier to feed on the newly-planted smaller-coned exotic conifers. If a population experiences a significant preferential emigration of small-billed individuals, the direct consequence that one might expect for the remaining population is an increase in bill size...
Thus I remain unconvinced that you can say with any confidence that "the really thick-billed birds one sees in Scotland are not, and never have been, "Scottish Crossbills"." Maybe they are, and always have been.

 

[lewis20126]

of scotica is from 1870.

But I will reiterate my earlier suggestion... All apparently started with a pine-adapted crossbill population with medium-large bill, presumably in equilibrium with its environment, where the only conifers were Caledonian pines—

The Caledonian Pine Forest is only about 9000 years old: http://en.wikipedia.org/wiki/Caledonian_Forest

Presumably the founder population would have been either a large-billed Parrot type Crossbill or a small-billed Common type Crossbill. I guess there would have been some isolation as there would have been few if any conifers in southern England until relatively recently (no native conifers which could support Loxia?). My guess would be a Parrot type coloniser but I'm not too sure about the spread of the various conifers upon glacial retreat, that being the key factor.

cheers, alan

 

[lewis20126]

eg Larch was not introduced into Briatin until the 17th century. Small-billed plain-winged Loxia must surely have been rarities in Britain until relatively recent times.

cheers, alan

 

[l_raty]

The Caledonian Pine Forest is only about 9000 years old: http://en.wikipedia.org/wiki/Caledonian_Forest

No, indeed: before this Scotland was entirely under the ice, and therefore supported no forest. (Ditto for Scandinavia and the northern part of Central Europe, including all of the current range of Loxia pytyopsittacus.) At this time, the conifers were further south, and I would expect that they supported populations of crossbills: the trees and the birds may well have moved north together as the temperature increased; then the range of the trees contracted, Caledonian pine being the only conifer to persist, and a bird population would have become locked in the remnants of forest.
I understand that Abies (fir) and Picea (spruce) were both present at this time in Britain...? (Eg., see pollen evidence, Fig.14-15 (Abies) and Fig.26-29 (Picea) in Terhürne-Berson, 2005.)