Friday, 17 December 2010

Watch Out ! 'Ere Comes The Old 'Bill ! EDITED

Apologies for paucity of posting lately - catching waxwings, catching up with work, catching colds yada yada...

After my revelatory "new" Scottish Crossbill call announcement, which to my dismay has not yet featured on the front of "Time" magazine, "New Scientist" or the Graham Norton Show, I thought it would be helpful if I posted an 'old' Scottish Crossbill call (click to enlarge):

This flight call was recorded at Glen Tanar NNR on 8th August 2004 with my then trusty Monocor Shotgun mic direct to Sony 710-MD. This call is very much per the literature (Summers et al, 2002) in that it matches frequency and structure for Fc3 = Scottish Crossbill. Note that it appears to show the all important trailing element behind the main "up-down" components of the first element. This is the feature that is generally used to categorize scotica. However, it is very different in visual spectogram appearance and in sound to the 'new' type one I posted on here ( a few posts down). The "new" call is higher piched and the second element is usually higher in energy than in the "old" one. It is as if the call has evolved ....or perhaps it is the crossbills that have evolved ? !

My view ? Well I am not for one minute saying that the example of the "old" Scottish Crossbill from Glen Tanar is not a 'Scottish Crossbill'....except that it seems consistent with birds that I have handled and sound recorded that would be classified as Parrot Crossbill, albeit at the lower spectrum of minimum bill depths (11.9 mm upwards). It also doesn't sound like the 'new' call types ( which appear to biometrically match scotica) - if we take away the second element, which possibly appears to be a harmonic trace of the main call, what we effectively have is a Parrot Crossbill call = Fc2, in fact many caught and released Parrots give a call that contains these type of 'traces':

Not all Parrot Fc's are inflected in the main downward component ! The harmonics here are admittedly much fainter than the Glen Tanar example above, but in terms of sound this is negligible (compared with the new Scottish call). In Parrot, most of the energy is in the main downward component of the first element and it is this, and the lower overall frequency, that avoid confusion with the Fc1 variant I call the "parroty" Fc1. Here is a Common Crossbill call, a Fc1 "Parroty" type that also contains the harmonic artefact:

In essence the'trace' element appears and sounds as an artefact not a feature of the call. In the 'new' Scottish call the second element cannot be a 'harmonic trace' because, if you look at it closely, it modulates whereas the intial element (that it would be tracing) doesn't:

This may be as a consequence of the bird using its double syrinx ? You can really see that these calls look nothing like anything else on this page ! I should add, that although I refer to these particular Scottish calls as 'new' I have actually recorded them since 2004, they are new in that they don't seem to have been described proviously and certainly not matched to biometrics. In the 'new' call the second element functions as a feature of the call, ideed it is the most important structure in giving the call its particular timbre and resonance. To me, this new call sounds completely different, and more importantly it matches the bios and ecology of Scottish Crossbill. However, some Common Crossbills here in Scotland may also give di-syllabic calls that closely resemble these 'new' Scotbill types - the clincher here seems to be that the second element is higher in frequency in relation to the first element with Scottish, though this is pers.obs based on in the hand bios. Time will tell. A final word on harmonics if you use fine microphones ( I use Telinga Stereo DAT, Twin Science and Sennheiser ME67) these harmonics are usually more apparent, especially at closer distances.

So, rather appropriately for this time of year "in with the new out with old" ? But remember folks, I am the one that thinks that the (Scottish) Parrot  Crossbills are the REAL (relict) Scottish Crossbills, so I don't know where that leaves us with regards to "old" and "new" 'Scottish Crossbills' that currently occur in NE Scotland ? Perhaps they are emerging "species" or morphotypes (is that a real word) ? 

Next up, a discussion (including audio examples !) of variant Common Crossbill Fc1's as this really needs addressing.

© Lindsay Cargill 2010, 2009, 2004


Loxia Fan said...

......I should have added that the Parrot and Common Crossbill flight calls in this post were release calls from trapped birds eg. full biometrics were taken, and classification was based on these. You can see the wingbeats on the sonograms !

Loxia Fan said...

..and the Scottish flight call added was from a trapped bird with full biometrics and a bill depth bang on for presumed scotica (eg. bigger than Common mean and smaller than Parrot mean).