That's Life

It seems Bird Life International have taken it upon themeselves to de-classify Scottish Crossbill as a species.....and then all X-Files 'n' mysterious they have erased all trace of this unofficial press-release SEE HERE ! At a time when their partners the RSPB have just surveyed the species using a scientific rationale and whilst a new Red Crossbill 'species' has been proposed in USA, this seems a strange decision. Whilst I often hint at sceptisim, or at least an open mind, over the current classification of scotica, I nevertheless do believe that there is at least one crossbill 'species' or type endemic to Scotland. Boffins at BOU can decide on what constitutes speciation, but it seems in some quarters that if birdwatchers cannot see a difference through their Leica's then it cannot be a species. While I can sympathise with birders is this rationale sound ? What exactly made BirdLife International reach this decision ?

Those friendly neighbourhood BF's have started discussing Scotbill again HERE. I am kind of glad that I can't participate as it usually gets a bit silly. However, the comments in post #14 :

"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. "

Not really wanting to single this guy out as he is only giving his opinion, this cannot be the case for the suggested indifference between crossbills, certainly morphologically. Birds selected for a particular conifer type would fluctuate (negatively) in numbers if that particular conifer type failed - this is one of the reasons crossbills migrate. By breeding with other types this would not necessarily ensure their, or in particular their offsprings survival - there is no advantage, quite the opposite possibly ! Even when several types of crossbills breed in the same area they breed with ones that look and sound the same. This is true even for Common Crossbill types. For example, a Parrot female will not mate with a Common male as the Common male will not be able to feed both himself, her on the nest and then chicks during a hard time of the year (Feb-April). Would it be advantageous to the Common male ? Well, if sucessfull presumably some of the offspring may have larger bills and be selected for a different niche, which would fit Jureks argument. My own thought is that he wants to be sucessful in passing on his genes to progeny who have a chance of survival. This would be with a mate of the same type and in an ecological niche that is optimal for that type ( eg. not a native Scots Pine forest in Feb-March). Thus, ecological niche specialisation plays a huge role in the assortative mating between Common and Parrot Crossbill - between Scottish and Parrot, well that could be diferent.

A Common Type 1A female I caught in June this year:

Spruce Muncher

And a Parrot female I caught in August 09, notice the pronounced gonys (used for feeding) and the nictitating membrane on the eye:

Pine Muncher

Still think they are the same species ? Surely not......

Scottish and Parrot Crossbill nest failure can be as high as 40-50% in some Springs. Genetics, in my opinion, is still an emerging science and more refined techniques may show genetic variation between the Loxia taxa. We will see. I guess the sceptics can cite Northern Bullfinch as a case against scotica's or possibly pytyops full status - it is bigger than the West European and UK races, but essentially, as far as I know, it still feeds and behaves as a Bullfinch ? It has a different call from those found in Scandanavia and Britain ( sound familiar ?!). Do these large Northern Bullfinches breed with the smaller forms ? Is there any genetic variation between these races ? For a thing to be half as big again there must surely be something in the genetic code ? Same with Parrot Crossbill in my opinion - it is much bigger than curvirostra. Northern races of birds do tend to be larger, but these are in Scotland. Just because we haven't found a genetic difference yet it doesn't mean it does not exist ( sounds like a IBWO believers mantra, oh no !).


My feeling is that each crossbill 'type' has a natural variation within its population as a whole and in adverse years certain individuals will be better adapted and will survive (in greater numbers)and others will die out. This can be seen on a local level - here in Scotland there was a sitka and larch failure last winter and Common Crossbills largely had to feed on Scots Pine. Only the fitest birds selected for that environment will have survived (or remained/bred) eg. birds with bills that could have coped with opening closed, hard Scots Pine cones. Subsequently, certain call types (and morph types) were not present in the region ! This would perhaps explain the variation in bill morphology of the various cryptic curvirostra types. As far as I know bill plasticity has not been fully explored so this is purely hypothetical on my part but it is something I hope to examine long term by studying a dormant population of large billed crossbills in Scotland as well as invading crossbills of the same call type over several influxes eg. many years. In years of good local larch and spruces one would expect a larger range of bill sizes amongst dormant crossbill populations, with smaller billed specimens sucessfully feeding on the non-native tree species. In years of non-native failures one would expect modal bill sizes to shift upwards.

When we classify Crossbills to species we tend to use measurements like bill, with mean bill depths often cited, but I think this is potentially misleading -Parrot Crossbill (as things stand) can have a bill depth anywhere from around 12.0 (!) through to 14.1mm and Common from around 9.0mm to 11.7 mm. Edelaar, van Eerde and Terpstra found for type A (Dutch) males that the mean bill depth was 10.62 mm with a range of 10.0 to 11.7mm. Again, this is a difference of 1.7mm, which is quite significant within a type (and which overlapped with the other type in the study).

I also think a bit more needs to be done on the inheritability of bill morphology in wild Crossbills. Studies in capativity show positive inheritability of bill size from parents, though personally what I felt that data showed was that a clutch of offspring averaged the midpoint of parents bill depths but exhibited quite a bit of variation matching that of the parent sample eg. range of bill depths for adult male scotica was 11.2-12.4mm, and for adult female 10.2 - 12.1mm. That is 1.9mm of variation for females, quite a bit of variation in crossbill terms.

However, in captivity they (adults and progeny) are not subjected to the pressures of a dynamic natural environment (where food suppy and type and temperature are not controlled), and afterall the catalyst of Darwinian evolution is natural variation within a population: without variation there can be no evolution. Such variation also promotes the survival of the 'species' by increasing it's adaptability to potentially adverse enivironmental conditions that may occur. Even assuming a high inheritability rate, if a particular population of crossbills ( type) has such a natural variation in bill structure (depth/shape), which they clearly do, and birds with similar bills mate with birds that have the same size of bills ( as they have been found to do) then this means that the progeny of the population as a whole will continue to have a range of bill sizes ( that they have inherited). But some will be better selected for particular environmental conditions than others will. Crossbills within that population are thus potentially selected for cones and seeds of various sizes - there will be an optimum, but there is an insurance policy that Nature has provided, one that is occasionally asked to 'pay out' when a cone crop fails. This might be the key with crossbills and why we all have nightmare identifying and classifying them.


This is one of the reasons I like studying crossbill calls, something which (unfairly) takes a fair bit of bashing as being 'pointless' it has to be said. Finches can learn calls from their parents and will also sychronize calls with a mate - the latter is something I have evidence of with Scottish Crossbill on two occasions. Mainly this is between a pair of the same call type or species ( as my examples were), but it has been noted in USA of birds of different types. But surely this makes crossbill taxonomy using calls even more vague: if the birds change calls, or birds of a specific type learn the call of a male in a mixed pair then how do we know who is who ? Well I don't think this is a reason to throw in the towel. It is a bit like being born in England but growing up from a young age in Scotland. You are English as a race but culturally there is a fair chance you will sound (and possibly behave) Scottish ! You may even attract a Scottish member of the opposite sex as a partner. To all intents and purposes you be will identified as Scottish by the Scottish population at large - you are effectively 'naturalised'. Biometrics do not have this 'cultural' focus but vocalisations do. In Crossbill terms, we may not really know what provenance a particular hybrid specimen is, but we at least know it thinks it is Scottish and will presumably act as expected ( if it can).

If hybridisation is a problem (and I am not sure it necessarily is) and is indeed the explanation for the genetic indifference, then surely it is as a result of specimens at either extreme of the bill depth ranges for a given type. Thus, a small billed Parrot may pair with a large billed Scottish Crossbill (at it's upper range) - they will 'look' the same (to each other and us !). They may even synchronize their calls as pairs often do. However, they will still have to contend with that harsh Scottish Spring which will select for the very fitest of individuals sucessfully breeding.........

You Say Parrot I Say Potato

"Shurely a Parrot Croshbill Mish Monneypenny" ?

Following the BBRC decision to remove Parrot Crossbill from the BBRC list as outlined previously on this blog, and also reported in British Birds May Vol.102 p.275, the debate has ensued as to whether or not this is a good decision. There are some sensible points discussed HERE, though I am not sure about posts # 44 and #45 - and there was me thinking I was such a friendly and amiable chap ( which I am when you get to know me.....honest) !

For me BBRC decison on Parrot Crossbill is a kind of revelation, as last year the editor for the North East Scotland Bird report quite correctly insisted that I add a caveat in the text that none of my Parrot Crossbill records had been submitted for review by BBRC. So were my Parrot records credible ? This was my primary concern as, without the blessing of BBRC, these 'unverified' records (all mine !) could perhaps be seen as vague at best - "stringy" is the correct term, as I understand ? However, we all know that biometrically and bio-acoustically "Parrot" type birds have been getting trapped and sound recorded in Scotland for well over a decade. Thus back to the BF debate, which sadly I can't take part in. I sit on both sides of the fence on this one for the following reasons:

My own records of Parrot 'type' Crossbills now gain credibility and there is now an acknowledgement that Parrot type birds breed and are resident in NE Scotland, differentiated from 'migrant' records. Hooray, result !

But:

Presumably all records submitted by other parties will also be accepted without verification ? But,what if these are mistaken or errant - given the ongoing confusion amongst most birders between Parrot, Scottish and even Common is this a wise policy ? Also, what about 'true' migrant Parrot type birds on Fair Isle or the Norfolk Coast - do BBRC not want descriptions of these either ?

Now, this really makes me sound omnipotent and selfish, doesn't it ? Basically, what I can be accused of saying is that I can ID Parrot Crossbills and nobody else can ? Well no actually, that is not what I am getting at, and far from it really. It is not that 'other' records can't be trusted but, in my defence, a lot of pictures I see of 'Scottish Crossbills' on the web, and even published articles, appears to be one of these Parrot type birds. So, if someone reports a specimen as Scottish Crossbill then it is, in all probability, very likely a Parrot Crossbill ! This may work in everyones favour regarding accuracy eg. a big billed bird is most likely a Parrot type, however some Scottish types do appear to overlap with the smaller end of the Parrot size range - at least they are considered as Scottish just now, but may be a modal bill size all of their own. Readers may remember a long since hacked and deleted post on this blog about a large billed crossbill sighted in Wales by Dan Brown ? My advice was that although the bird appeared to have a large mandible this could have been out of proportion to it's body - a small bodied bird with a disproportionately large bill can look 'Scottish' or 'Parroty'. There is a good example in Birds of Scotland of a profile of a Scottish type bird with a HUGE honker of a beak in the photo, yet it's bill depth was bang on for Scottish. It clearly had 'big beak, smaller head' syndrome !

Scottish, Parrots or Common? Ask the audience? Phone a Friend? Final Answer ?

For those sound recording to verify their 'observations' the flight calls are also very confusable, as I see time and time again - according to Knox, and Constantine and Mullarney, Parrot flight calls in Fennoscandia and on the continent can be quite variable, though I am not sure if they confirmed this with biometrically verified birds. Magnus Robb has also recently recorded some variation in Parrot Crossbill call types from several different irruptions into Holland. In Scotland there does seem to be some variation with Fc2. Poor sound signals can result in calls losing important structural features and frequency can vary with distance, and, it seems, simply by natural variation within a call type. Thus, these calls are easily confusable on sonogram. By ear, without much experience or suitable comparison, it would be very easy to confuse Parrot EcD with Common EcA, the latter sounds slightly higher, hollower in timbre and with more obvious harmonics - but what does that actually mean in the field ! ? Parrot Fc2 can also be very easily confused with the thinner "Cheepy" Fc1 of Common Crossbills that are prevalent up here in Scotland just now, both on sonogram and 'by ear'.

However,with tangible physical measurements such as biometrics or a sound recording a record can be updated or reviewed in the future should our knowledge change regarding crossbill speciation. A statement " 5 Parrot Crossbills at Anagach Wood" cannot. It simply infers that there were (possibly) several big billed crossbills there. Photos help to some degree but can be misleading - lots of shots of the same individual from different perspectives are often required.

Back to the Bird Forum debate and some of the comments, some of which mention me personally. James Spencer (Hotspur) writes in post #5 :

"If you adhere to Lindsay Cargill's identifications then most of the Scotsbill in the various bird galleries are actually Parrot Crossbill".

Yes and no James - I have basically suggested this as a generalisation, but I have not identified every single photograph on the web ! There clearly are some Scottish Crossbills on web galleries - there are even some of mine on the dreaded Bird Forum ! Granted a large amount of birds labelled as 'Scottish' would be classed as 'Parrot' type by me using my own experiences and under currently accepted classification and thinking here in Scotland eg. bios and calls as they stand.

In post #25 Richard Klim writes:

"Laurent Raty made the following comment during a recent ID-Frontiers discussion about the recently-described South Hills Crossbill (suggesting that Parrot is now more likely than Scottish at Abernethy):

"... medium-size-billed crossbills in Scotland [Scottish crossbills] are now found largely in alien conifer plantations, rather than in native Scots pine forests where they are supposed to have evolved [and where bigger-billed birds now occur]."

The quote by Laurent, a very knowledgeable and nice chap, regarding medium sized birds is true..........to an extent ! Scottish can occur in alien conifer plantations but generally at particular times of the year. This caveat is very important: In February scotica is usually back on territory in either native or plantation Scots pine. The problem being so is curvirostra, though some will feed on Larch until April if it is still present - this winter the Commons, and Scottish for that matter, were predominantly found on Scots pine throughout the year due to a Larch and Spruce crop failure. Scottish will move on to Larch in late summer and early Autumn and will flit between Larch and Scots Pine through the winter. They will aslo subsist on Spruce, particularly Norway if present, and Lodgepole.

However, all of this potentially gets even more complex, and this is my point: how may people are mistaking Common Crossbills for Scottish Crossbill ? Parrot and Scottish are always considered the ones that are confusable, but in reality it is probably Common and Scottish (under current classification criteria) that cause most problems. The female bird in the top banner of Loxia Fantastica is a second calendar year Scottish Crossbill. Be honest: how many of you would have had that down as Common ? The bill shape is not typical Scottish, certainly not from that angle, but the plumage definitely is, though Common's feeding exclusively on Scots Pine may also appear 'dusky'. The bird gave a Scottish type call.

In balance I think the BBRC decision is the right one - a few misidentified specimens of either species will be overshadowed by the hundreds of verified (but not submitted records) that crossbill researchers and enthusiasts collect, that till now have always been in a dodgy 'are they aren't they' area ! Bear in mind most of my records are confirmed by either calls or biometrics (colour ringed birds that have previously been trapped). Actually, in my opinion they still are in that 'dodgy area' for reasons cited in a post way down below regarding the possible identity of the true relict Pine Crossbill of the Great Forest of Caledon ( just my thoughts, half baked maybe), but at least it gives us an position to move on from should classification be altered in the future. 'Parrot Crossbill', in my book, is merely a label for the largest billed crossbills that exist in Scotland and also on the continent. The Scottish 'Parrot Crossbills' may be the 'same stock' as their continental counterparts, though maybe they are not, and are actually the real relict 'Scottish' pine wood species. Certainly food for thought I think

"Touchdown " - The Eagle Has Landed !

Evidence of Type 4E Crossbills On The Mainland !

Monday 6th July


I managed to get out on Monday 6th July for a bit - it's a long story but things have been mental lately. I will not bore you with details but don't get involved in a car smash even when it is not your fault.....me okay, car not I am afraid. I am in hire car for 12 weeks.......

First site was East Durris. Many cleg flies on arriving into car park - not a good sign. On goes liberal doses of Autan ( have you ever been bitten by a cleg fly ? Not a horsefly, a Cleg is MUCH worse as it slices into your skin and blood pishes out !). Anyway, as I was doing that two Common Crossbills flyover, both giving a Fc4 ( same as those on Shetland currently). I didn't get a sonagram, but to be honest, and without sounding smart, I didn't need one as to me Fc4 is the easiest of the 'Common' flight calls to do by ear. But a few minutes later they went back over and this time the Telinga got them, and yes they were Fc4 confirmed on computer later that night. The larches at this site were still green ( they do use them like that) but not quite there yet I thought.

I decided to hit a site a few miles to the West just before Strachan ( pronounced Stra'an). Here, on getting out the car a flock of at least 40 went over, and although it was a cacophany I could clearly pick out Fc4 and EcE from them ( the sonogram later confirmed this).

I followed parties of birds around for an hour and a half before a really serious thunder storm and torrential rain curbed activities. All the birds I observed were feeding on plantation Scots Pine cones that still had some seeds. They were highly mobile suggesting that they were being very selective about which cones they were using eg. ones they could open, and there weren't many of them. I saw quite a few males with the faint fringing on the greater coverts, again like those on Shetland. I also saw a courtship feeding between a male and female and these were 4E types ( so they might breed straight away !? ). I should point out 4E types have gone of the radar over the last two years in my area - I have recorded several, but nothing like the 25% or so that was present in 2007. On Monday I also recorded quite a few 1B types, one identical to a sonogram Dougie Preston sent me and also the 1A types that have been all over the place since the turn of the year.


Wednesday 15th July


Same site as second location at Strachan on 6th. Lots of birds and now feeding in the larches. Many singing, some with a song I have not heard............Some 1A types but many 4E's with their very distinctive flight calls ( these really are easy to do by ear, the easiest in fact as above !)


In upper Deeside semi-natural habitat Fc4 was present, so they have apparently penetrated the full Dee Valley. This is the first year where I know for sure the call types of the immigrant crossbills ( eg. are not just roaming or displaced resident birds) and have tracked them pretty much from the coast right up the valley, approx. 80 kms !


With many being reported in the South and East of England just now it would be very interesting to see if these are also 4E types - they may not be. Anyone ?

More Thoughts On Irruptive and Wing Barred Crossbills

Reading through Birding World Vol.21 Number 8 Issue 260 it struck me how many of the Two-barred Crossbills in July and August influx to Shetland last year were juveniles ( in streaked plumage). The consensus was that these 'streakies' fledged in Spring 08, which according the BWP is fairly typical. There were also adult birds accompanying them and these had undergone post breeding moult (from the pictures) eg. they were in at least their second year.

On the other hand, the Orkney 'wing barred' crossbills in June and July this year to me look like birds which fledged very early this year or possibly late last year, typical of curvirostra's breeding patterns. It is unlikely that they would have such 'retarded' wing bars if they were genuine Two-Barred's in their second calendar year ? Even the streaked juvenile two barred's last year had strong white on their greater coverts. It is also unlikely that two barred crossbills that fledged in Spring 2009 would be so advanced into their post-juvenile moult as these recent Orkney curvirostra type specimens, again based on the streaked juveniles last year in July and August. Many of the birds that have been photographed recently in the Northern Isles appear to be these 'first summer' (or second year) types, exhibiting fringes on particularly the greater coverts and some on the tertials, with mottled body moult eg. males with green blotches. A good example of a wing-barred Common that even has broadening fringes towards the body ala Two-barred is HERE - still doesn't look 'right' for Two-Barred does it ?

I have been pondering where all these Common Crossbills have come from and why ? How about these scenerios, and please bear in mind I am just 'thinking out aloud' here eg. I reserve the right to change my options or be completely wrong !

1) The Common Crossbills are from either/and/or Finland, Norway, Sweden and North West Russia. A localised Larch and Spruce failure has meant birds now have to move from there as Scot's Pine will have shed most of their seeds. They are errupting from these (nearer) areas fairly recently.

2) The birds have possibly been moving from much further East or North/East for several months, foraging crops as they go, after breeding (late last year or late autumn) and there is a 'lag' effect. If they were coming from further East, then settling temporarily in areas in Finland, Sweden etc where other crossbill populations may also be present or resident, then we could assume that these would also be moving now for the same reasons - if so, there could be differences in call types, biometrics and stable isotope analysis of feathers for these different populations.

Common Crossbills normally errupt after a successful breeding season and/or coinciding with a poor spruce crop. This means there is usually a high percentage of juveniles. For example, in 2005 there appeared to be a significant proportion of streaked juveniles on rigs, Fair Isle etc.

If the 2009 irruption does not have a high incidence of streaked juveniles (which so far it doesn't seem to) then this possibly implies scenario 2) whereby regionally 'settled' birds have bred ( in the Autumn/Late Winter) and this food source has now become depleted and they are moving westwards over several months. Where they have come from is harder to establish, though stable isotope data should determine this ( to some degree). However, the calls so far appear to be only of one type predominantly 4E with only one 1B thanks to the efforts of Dougie Preston and Hugh Harrop. It would have been interesting to know what the Orkney and St.Kilda ones were. Perhaps 4E is less selected for the crops that are available where they are moving through (possibly Scots Pine which is still holding some seeds, though I have several records of 4E's using Scot's Pine in midwinter in Scotland - nothing is straightforward with crossbills !). If the call types of the influx birds are primarily of one variety then this perhaps suggests only one curvirostra type/morph/cryptic species is errupting the continent. It would be an interesting opportunity to try and understand why this is the case.

What would have been extremely interesting is if anyone had been sound recording the calls of crossbills in these continental regions over the last year or so - we basically need several LoxiaFan's in Russia, Finland, Sweden, Norway and on each of the Northern Isles ! We would then know what call types were present and also if there were any changes, and if these changes can be 'tracked' and in what directions. I would be particularly interested in comparing call types with deuterium levels in feathers maybe this could geographically map regional 'dialects' in crossbills populations within Europe as has been done in the USA. Knowing the status of the various cone crops in these areas would also be helpful.

I'll sleep on this and see what I think, but really these birds could have come from anywhere, but the significant observation here is the apparent lack of fresh juvenile birds and the call types of those birds that have been moving through Shetland.


I told you I had a feeling about this year and an irruption !

Raising The Bar

Thought this might be of note to those currently interested in wing barred crossbills in the northern isles just now. Many thanks to Stuart Reeves for passing these on to me last year ( or year before ? ) -








I also recall reading something about the two-barreds from last years irruption in either Birding World or British Birds earlier this year or last year.

Hope this helps - if anyone could get me some recordings of any crossbills from up there that would be fantastic !