Wednesday, 8 July 2009

"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 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 ?

Sunday, 5 July 2009

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 !

Saturday, 4 July 2009

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 !

Friday, 3 July 2009

Barred For Life

Following Alistair's comments below about the Orkney wing barred Crossbills, I thought I would post some pics of 'pine' crossbills with similar plumage structures.

First up, a first winter male, photographed in Deeside in October 2005, the picture quality is absolutely shocking ( light was bad and from the looks of it I might have been pointing the camera the wrong way round !):

However, you can clearly see it a male Parrot Crossbill ( first winter) based on the massive bill depth, and it has white fringes to the greater coverts and tertials, with some faint brown fringing on the median coverts.

Next, a cracking first winter male Parrot Crossbill caught in Deeside in October 2006:

This specimen (bill depth of 13.2mm) has light pale fringes to greater coverts, median coverts and tertials. Normally, these fringes if present are more buff brown in colour. An open wing shot of same bird:

I know some people don't like 'in the hand' shots like this but please appreciate these photographs are only taken to record such plumage and bill shape details of individual colour ringed specimens - they are not 'trophy' shots ! If they had not been taken you would not be reading this post ! All birds are processed as quickly as possible and released unharmed - this particular specimen has been re-sighted many times since its capture and release in October 2006 including feeding juveniles in 2007 and resighted again just a few weeks ago.

The Orkney wing-barred crossbills ? Well the female looks like a Common Crossbill version of my birds above. The male is obscured by foliage but I agree with one of the posters that the fringes look brown not white, and that the tertials are not visible. So for me one definite Common Crossbill (female) and one 'most likey' Common (male).