Saturday 26 March 2011

Toop, Toop, Choop, Choop !

No, I haven't lost my mind, but rather a short discussion of phonetic crossbill calls ! I get many references in emails describing crossbill calls in the field using phonetic descriptions. Most existing phonetic descriptions in the crossbill literature, other than those by Magnus and Sound Approach, are errant or misleading in my opinion, particularly for Loxia scotica. They also may not reflect the 'current' evidence either. Actual audio recordings are preferable, however the following may offer some clues in separating Parrot Crossbill from Scottish Crossbill in the field.

Parrot Crossbill

Flight Calls are a distinct "Choop" or "Chup", emphasis on the "oo" or "u". These can also sound 'flutey' (a term often wrongly used to describe Scottish flight calls) due to a pronounced harmonic that is often present ( and which can make them appear on sonagrams like published Scottish flight calls). Birds may also give a more subdued "tip, tip, tip" call when in 'cryptic' flight (similar to those given by Bullfinch). They sometimes give these on release after being captured and ringed. These can appear as single descending streaks on sonagrams.

Excitement calls are a lower pitched (than flight calls) 'cluck' reminscent of a Blackbird alarm call, or more closely a Jackdaw (and between the two in 'pitch' and timbre). Aurally, Parrot excitement calls sound very similar to Common Crossbill EcA ( or "British" ala Sound Approach) and it takes much experience to separate them by ear in the field. In such cases a look at the bill should help diagnosis, but not always it would appear !

Scottish Crossbill

Recent evidence that I have collected and matched with biometrics shows intermediate billed (Scottish) give a 'di-syllabic' flight call sounding as a "t-reep" or sometimes a 'lispy' "th-reep". This is much higher pitched than Parrot flight call and in fact can not be confused aurally with ANY commonly occuring Loxia in the UK ! NB. THESE CALLS ARE DIFFERENT FROM THOSE THAT HAVE BEEN PUBLISHED !

Scottish excitement calls are much more 'hollow' than Parrot Crossbill, and sound like a "tonk, tonk" or "tunk, tunk" - I think it sounds more stacatto (abbreviated) than Parrot and timbrally similar to wooden claves or woodblocks being struck (for any would be percussionists out there !). In the field it is VERY similar in tonal and timbral quality to Common Crossbill EcE or "glip" excitement call, especially if the harmonics are less pronounced ( which makes the call look very similar on a sonagram too !). This is a RARE call, by far my rarest recorded Crossbill Excitement call, suggesting this call, like the flight call, may be in a state of flux - time will tell.

One word of caution. Often people describe large-billed crossbills giving very 'deep calls'. In cases like this, assuming they are correct, they are describing Parrot Crossbills as both Scottish flight and excitement call are higher pitched than Parrot, and typically much more like those for Common Crossbill. It is worth reiterating that 90% of photos I am sent or see on the web of presumed 'Scottish Crossbills' are in fact actually Parrot Crossbills (in my experience) ! My advice: leave the camera at home, buy a mic and recorder, think about the above, and learn about the vocal dialects of the crossbills in your area.

Friday 11 March 2011

I Don't Just Do Crossbills !

As many readers may know House Sparrow numbers are in sharp decline and the species is now Red listed. In my own garden in central Aberdeen I used to get up to about 60 at once but here too the numbers seem to have decreased in the last few years, and there is maybe a population of around 40 to maybe 60 in the area. Last year I know that they had several broods so juvenile survival must be very poor, either that or the birds are dispersing locally. I have ringed about 90 House Sparrows (with little effort) and have so far only had two retraps, and reckon at the moment there are only two or three metal ringed birds visiting.

So, I have just started a RAS project organized and sanctioned through the BTO to study my local House Sparrow population - RAS stands for ' retrapping adults for survival'. By colour-ringing the birds and reading the combinations in the field it is possible to get 're-traps' without physically re-catching the birds. By ringing enough birds and by getting as many re-sightings of individuals as possible we can deduce the mortality within the population. Over and above this I am going to colour ring as many of the newly fledged juvenile birds as possible to try and work out some numbers for juvenile mortality (and the time scale of this), as well as measuring any localised dispersal. The presumption is that the Sparrows will continue to visit the feeders so should be seen again (if they are not predated or die from disease). Dispersal can be measured by checking feeders and Sparrow perching sites in the neighbourhood. Disease may also be a significant factor in mortality- I rescued a male House Sparrow in December last year suffering from avian botulism, but sadly this bird expired ( horrible stuff, I hope none of you have to deal with that). I should add that this bird was a mile from my house so not my feeding regime causing the problem.

The bird in the photo is an adult male A01, now getting the distictive black bill of the breeding season. I am using Interrex acrylic rings designed and manufactured in Poland. The rings are sealed with cement to safely secure them and to prevent removal and are fitted so they can't extend below on to the foot or above the tarsus 'knee' joint. They are easily read with binoculars on perching birds ( when facing the right way !) or can be image grabbed from digital photo sequences.

I know many birders don't rate Sparrow but I can't understand this - they are very 'happy' social finches, the males striking when in breeding plumage and I for one can't imagine the dull silence that would prevail if there were no House Sparrows chirping in my garden. Let's hope the streets and fields don't fall silent.

Thursday 3 March 2011

Ground Control To Major Tom...What Gear Do You Use ?

Contact details have been added in my profile on the right. This is for use of any genuine enquiries and for colleagues who have been unable to get me at my old email address eg. Ringers, crossbill sound recordists, birders in Northern Isles who are sighting and collecting crossbill call data, people with dead or injured crossbills, or people with sightings of colour-ringed crossbills.

Unfortunately, due to time constraints I can't respond to general enquiries about crossbills or location requests for Parrot and Scottish Crossbill. This includes identifications from photographs so please don't send any - sorry. Such emails will not be responded to so to avoid potential offence please don't waste time writing them ! I also can't spend time writing extensive emails advising on sound recording equipment - I recently did such an email to an RSPB researcher, took me an hour and I didn't even get a reply saying "thanks" so no more I am afraid. There is now plenty info on the web on this, but for those interested I have used the following since 2006:

Telinga Stereo DAT and Twin Science Microphones
Telinga Pro 6 Handle
Fostex FR2LE recorder
Fostex FR2 recorder
Sennheiser ME67 (occasionally)
Sennheiser ME62 (occasionally)
Sony MZNH900 Mini disc recorder (with Telinga Power Box)
Sony MZRH1 Mini disc recorder
Beyer Dynamic DT990 'phones
Raven Lite and Raven Pro Software
Adobe Audition Sound Editing Suite
Misc Leads and connectors  from FEL Communications (excellent stuff btw guys)

Quite an arsenal when you see it written down.....

Sorry I can't respond to every enquiry but I do also have a job running my own business as well studying crossbills in any spare time !