Wednesday 28 July 2010

Getting All Excited About Scottish Crossbill !

I am in process of re-evaluating some of my early recordings for a couple of upcoming papers (finally), one of which is now drafted and just needs the supporting sonagrams and pictures compiled and added in. Raking through the material I came across this sonagram, probably one of my best ever of a Scottish Crossbill, recorded near its nest at Glen Tanar on 11th April 2005 ( yes I really have been doing this stuff since then ! EDIT: actually, since 2004):

Scottish Crossbill Excitement Call

A fantastically clear sonagram of a typical Excitement Call C (EcC) diagnostic of Scottish Crossbill per Summers et al, 2002. The really amazing thing is this was recorded with my Czech Monocor short gun microphone (which was as noisy as hell) and my first Mini Disc recorder a Sony MZ-710 ! Not a Telinga or Fostex in sight ! Just shows you what you can do with a bit of fieldcraft (and field time) and the right conditions ( there was no wind and the bird was alarming about 12 feet away from the mic). In those pre HiMD days I had to re-record ALL the tracks  from the line out into Audio Lab via the computer and then process the sonagrams using a program called GRAM32.

I should add that this call type is now quite rare, having only recorded it in this form a few 'handful and footfall' times. Some interesting material regarding the call structures of Scottish Crossbills is imminent.....all is not what it seems, keep tuned.

Saturday 24 July 2010

Catching Pine Crossbills, Upper Deeside, 21st June 2010

Crossbills are notoriously difficult to catch in order to ring as you cannot bait sites like you can for other finches - they are specialised to feed primarily on various pine cones and there are usually millions of them about so no joy there ! Usually crossbills are caught when they come in or out of drinking pools. I believe Dutch ringers use 'artificially' created drinking sites and also use caged decoy birds to lure crossbills in which sounds very efficient ( and interesting). Here in the Scotland we only tend to use sites that the crossbills themselves visit naturally on their own accord and we don't use decoys ( though an endorsement to allow this can be applied for). Many man hours can be spent finding and reconnoitring these sites which is why I, and others, are quite guarded about where we are operating and catching birds. Last year one of my pools was compromised twice by photographers (the worst kind of disturbance) so don't take offence if I don't disclose sites, it is nothing personal !

Crossbill's drink obviously to sustain themselves, however, there is also a more 'cultural' purpose to the process. The birds will often sit in a perching tree near to or directly above the pool and the dominant male will sit right on the crown of the tree, sometimes singing or preening. There is a 'pecking' order to how the bird are organised within the tree, with more dominant birds asserting their authority, and often these birds will drink first. One often finds that these birds may actually drink twice - I have observed this several times thanks to colour ringing individuals. However, sometimes extra keen juveniles bail in first and these are often caught more easily. I refer to such pools as 'cultural' pools that is they are long term historical drinking sites where social behaviour and interaction can be performed. This is opposed to sites where they drink 'ad hoc' or opportunistically eg. near to where they are feeding and are thirsty at a particular moment, a puddle below a tree for example. All of this makes them exceedingly difficult to catch in any sort of numbers.

Monday 21st June had near perfect conditions: warm. overcast, and very importantly, little wind. Whilst setting up at dawn several birds came in to one of the pools I was hoping to catch. I backed off and let them down to drink - they could be trapped later when they came back ! I set up two nets and settled down very nearby so that the nets could be monitored constantly.Only an hour had passed and I caught some birds, a family of Parrot Crossbills and a Siskin (other birds drink at crossbill pools). The Siskin was processed first and released quickly.

The male Parrot Crossbill was an adult and was in post-breeding moult ( inc.wing moult):

Parrot Crossbill

Again, the bill structure to me is clearly Parrot, but for many birders this would be classified as Scottish. The minimum bill depth was in excess of 13mm so not Scottish !

The female hadn't started moulting her primaries but some tail feathers were being moulted. She also had a brood patch score (BP) of 4 (meanind she had finished brooding/breeding). The bill structure was Parrot:

Parrot Crossbill

The juvenile had a rather 'clean' look to its bill structure, almost Scottish in appearance but still too deep biometrically to be anything but Parrot Crossbill:

Parrot Crossbill juvenile

These birds were colour-ringed and processed quickly and released into the same tree whilst sound recordings were obtained of their flight calls. The colour ring sequence is unique to each bird and allows the birds to be 'recaptured' (by observation) without actually physically catching it again. Much useful information can be gathered from these observations of colour ringed birds and so far I have very important data on call association, feeding ecology, breeding behaviour as well as site fidelity and movements. The rings have no impact on the activities of the crossbill and some that were ringed in 2006 are still being observed at the same location.

I only had a chance to have a quick drink myself and another bird was caught. This bird, an adult male Scottish Crossbill, already had a metal ring on its right leg so was a retrap. Consulting my notebook it was ringed by myself and my trainer on 3rd September 2006 at the exact same pool:

Scottish Crossbill

This bird was also in post breeding wing moult with several primaries in the process of being replaced.  The minimum bill depth, believe it or not, is over a milimetre less than the Parrots that were caught, even though the shape is similar. This bird was processed and released very quickly, with the flight call recorded as he flew.

There was a lull of a few hours in the early afternoon. This so often happens, the birds just dossing about, preening, singing. Some interesting by-catch kept me on my toes with several Siskins and my first ever juvenile Stonechat. The latter was very interesting as there are usually several pairs with territories at this site but this year there have been none, so the bird I caught was most likey a roving juv from further up the Glen.

By late afternoon the action started again with two juvenile Parrot Crossbills caught in the other net I had set. These were probably caught as I have described above, that is piling in eagerly before the dominant adults ( who then sussed out the situation !). However, though they don't perhaps look as good, catching juveniles is actually better in many ways because we can age them exactly, that is as a first year or Euring 3J. We can also assume that these birds are on their natal site or certainly not far from it, so any movements can be valuable.

The first juvenile I processed had a stonking bill:

Parrot Crossbill Juvenile

From the profile you can really see that this bird, a typical Parrot Crossbill, is 'bill heavy'. Notice the very pronounced gonyeal bulge in the lower mandible.

The next bird, possibly a sibling, also had a pronounced Parrot type bill bill and was slightly smaller overall:

Parrot Crossbill Juvenile

The bird is being held in the 'reverse' ringers grip in order that the tip of the lower mandible can be photographed in the profile. Crossbills can be either left or right handed, or billed as it were, just like humans. I class the cross as being to the right or left based on the direction of the lower mandible tip, in this case to the left.

All in all a very sucessful day with a total of 5 Parrot Crossbills, one retrap Scottish Crossbill, 5 Siskins, 1 Chaffinch and a Stonechat caught naturally without bait. The retrap Scottish for me was the highlight in several ways. Hopefully the in hand bill profiles will be of help to birders in determining ( or not !) the Crossbill species and the text giving an insight in to the intricacy of crossbill study

Friday 16 July 2010

....Results just In

Well, that was a disappointing turnout given the apparent 'interest' in crossbills and the amount of crossbill sonagrams that are being posted on blogs etc. I don't think there is going to be a rush of contributions so well done to Dougie Preston and Stephen Menzie for being bold enough to have a go, and not a bad go at that, getting the species correct.

I guess people just don't want to appear "wrong" in public and perhaps this goes to demonstrate that identifying crossbills from sonagrams is just as difficult, possibly more so, than identifying them through a scope or images ? Or maybe my example was too difficult ? Well hey, it is a 'real life' snapshot of crossbill behaviour afterall !

Okay, there were two species, Common and Parrot Crossbill and of which there were 4 Common Crossbill individuals of the same 'type' (1A) and only one Parrot specimen. So a total of 5 Crossbills. Only the Parrot gave both a Fc and an Ec. Admittedly the actual numbers of birds was easier to ascertain from the recording which neither Stephen or Dougie had, though it can be seen on the sonagram.

So, here is my analysis ( all timings given are approx.):

1.0 secs = 2x Fc1 types. I call these "parroty" Fc1's as they are easily confused with Fc2. However, they much higher pitched than Fc2 Parrot and the descending element is much weaker ( thinner on the sonagram). Notice one individual is slightly lower pitched than the other, but still higher than Parrot.

1.3 secs = Bird "two"  of Fc1. Continues through sonogram faintly.

1.4 secs = EcA Variant, bird "three". Fundamental has an initial down turn or upturned 'horn' appearance. The harmonics are slightly different from typical EcA.

1.6 secs = Bird "one" of Fc1.

1.9 secs = EcA variant, bird "four".

2.0 secs = Fc1, bird "one".

2.2 secs = EcA bird "four".

2.6 secs = EcA bird "four".

2.8 secs = EcA bird "three".

3.3 secs = EcD Parrot Crossbill. There is no coinciding Fc here ( sorry Dougie) it is a feature of the excitement call structure (though may be related to a fc?). Notice how the Parrot EcD is lower piched and of a considerably shorter duration than the Common Crossbill EcA ( which they can be confused with aurally).

3.8 secs = EcA bird "three" and "four" together.

3.95 secs = Fc2 Parrot Crossbill - same individual as 3.3 secs. Compare with Fc's at start of sonagram, notice the Parrot calls are lower in frequency ( I call it pitch cos I hear it) and are a much stronger in amplitude. This gives a "choop" rather than "cheep".

4.1 secs = EcA bird "three".

4.2 secs = Fc2 Parrot ( same bird as 3.95 secs).

The appearance of a seemingly extra component on the Parrot Fc's at 3.95 and 4.2 secs can be misleading and may in the past have led to examples of this call being classified as Fc3 Scottish ( all will become clearer soon !). It is a harmonic of the main trace in my opinion. Only large billed birds I have handled have given this call on release.

So well done lads, other than the Scotbill reference, you got the right answer ( though the working out may not agree with my own analysis).

Just shows what information you can get from a sonagram. And there are people that say Crossbill calls are baloney ! Their loss.......

Wednesday 14 July 2010

S'on-ly A Game !

Many interesting revelations to come in the crossbill world very soon so keep posted but meantime a bit of fun ! If Menzie can put up blurry, dodgy pics of his Spanny birds and ask "how many species" then so can I with Crossbills. To make it easier though rather than photos of crossers, which most people seem to get wrong or concede "they just don't know", I have this sonogram instead:

It was recorded on 16th April 2009 in upper Deeside, native Scots Pine habitat (using ME67 and Sony HiMD). So, how many crossbills and of what crossbill species, and more importantly how many call types ? I bet Menzie gets them all correct, he always does !

Posts are moderated, but I will put the non Chinese spam ones on honest !

Spread the crossbill love.

Monday 5 July 2010

"Northern Exposure", Crossbills in Northern Isles....Again !

For the past few weeks (since approx. early/mid June) Common Crossbills have been trickling in through Orkney, Shetland and North Ronaldsay. Readers may recall that last year there was a biggish influx of type 4E Common Crossbills to mainland Scotland ( and presumably UK). I picked up  birds in decent numbers in lower Deeside by early July, where they had not been present previously that Winter/Spring.

Okay, guys and gals in Orkney and Shetland, what call types are you getting this year ? It would be very interesting to know. Colleagues in Grampian Ringing Group had a ringing recovery of a Common Crossbill in April near Dufftown. This bird was ringed in September 2009 in lower Deeside so had moved Northwards somewhat in the six months since ringing. Was this a bird returning 'back' to where it had come from ? My instinct is 'no', it was possibly part of a nomadic post breeding flock that was seeking a decent cone crop. But the possibility remains, especially given the accepted view is that birds move south and westwards.

So if this years influx of Commons on the Northern Isles is giving 4E calls does this mean they are last year's birds going home ? Maybe and maybe not. Maybe, for the scant evidence cited above and 'not' because some 4E's may have remained in Fennoscandia where there was a localised food source and are only moving now after breeding ( there are juvs in the recent photos I have seen of birds on Shetland). This is this 'lag' effect I spoke of last year, and this would depend on how far from the East the birds were erupting. However, if the calls of this years irruption is different from 4E then at least it rules out the 2009 population returning or a new one of the same type irrupting. As I recall there were some 1A's and 1B's last year also, though in much smaller numbers than the 4E's.

4E Common Crossbill

The other intruiging possibility is that of small numbers of Crossbills trickling in during the winter months and early spring. I have had Common Crossbills at coastal sites in November and December and two flew over my garden this April ( there is no substancial viable food source near me and I am less than a mile from the coast). These may also have been birds moving Northward back up the coast. However, I would expect the legions of Vismiggers to have picked up such movements if they were happening with any regularity ?

If anyone wants to post comments please do - I have not completely disabled the comments but am unfortunately having to moderate them due to the chinese spamming that seems to be more and more prolific on blogger these days !