Sunday, July 06, 2008

Meetings etc

Storm brewing

YNU meeting yesterday so very limited birding. Kestrels have moved their offspring near to the house, I'm not sure where these have actually bred because Ketrel has been very infrequently seen in the home tetrad this spring and summer.

Thanks to Dave Mansell for drawing my attention to a couple of interesting photos. In investigating these I had a look at Dave's own photos (all rather good) and was taken by his recent crossbill pix. The male, click here, looks interesting to me. My understanding is that this is unidentifiable from the photo alone and requires sonograms to prove what it is one way or the other. Or is it just at the "large bill" end of Common Crossbill variation? It is possible that the bill shape is exaggerated by a photographic anomaly in any case. I would be interested in any comments.

Dusk - better go owling

5 comments:

Loxia Fan said...

Hi Alistair,

Had a quick lookie. Bird in photo no.1 is a curvirostra - 2cy. Bird in photo 2, male, is possibly the same as the one in photo 3 ? The juv in photo no.2 is a curvirostra.

Regarding the big-billed male I have seen curvirostra with really big mandibles several times. In photo no.3 the culmen for me is way to shallow for Parrot which is generally much steeper or downcurved - a feature of pine adapted crossbills ( some say 'pine selected', for me the terms are synonomous !). Also in photo No.3 the bird's bill is open and there may be a drop of water on the lower mandible exaggerating the gonys. Most likey an abberant big-billed curvirostra.

Hope this helps !

Lindsay

Alastair said...

Lindsay,

Many thanks for your quick response which is very helpful.

All the best,

Alastair

East Ayton Birding said...

Put another shot of the individual in photo 3 on the website Alastair, this time a more heavily cropped image.

The birds in shots 2 & 3 were different individuals. If it stops raining, out of interest I may try and get back up in the forest during the week, and try to get a few recordings & additional images of the crossbills.

Regards,

Dave

Loxia Fan said...

Hi Dave and Alistair,

I had a look at the new cropped image. To me it looks like there is still a drop of water on the lower mandible giving a false appearance of an exaggerated gonys. Take away the outline of the water drop and the angle is that of curvirostra.

I had a similar individual sent to me by Alex Lees that his mate Dan Brown had taken in Wales. I gave a very specific account of large-billed crossbill ID (esp. from photos) but someone hacked into my blog and deleted all the posts! I may get round to putting this on the new website when it is up and running.

What I would say is that some crossbills are relatively quite small bodied (and headed) compared to other specimens of the same type. If a 'small' bird has an average bill then this can appear disproportionately larger compared with it's body. Check the pics of the crossbill profiles in Bird of Scotland to see what I mean! If you don't have this let me know and I will scan it and put it on my blog.

It is impossible to say for certain what 'type' your individual is but all the evidence I see suggests Common type, albeit with a honker of a bill. Equally, I see Parrot 'types' that have bill depths of around 12mm, much lower than the published figures. If you do go back do try to get some recordings (even poor quality)as this may give further clues. They will actually be more use for potential identification than photos. I will gladly give them a listen.

Note also the tick (Ixodes sp.) on the lower eyelid. Crossbills often come to the ground to grit and rake about for insects, as well as drink, and it must have picked this up then. Haven't seen this in loxia till now.

One last thing - if you know any local ringers tell them about the site and they may be able to catch them at the pool. The biometrics may be interesting ! However, this may stop you taking photos !

Lindsay

Alastair said...

Lindsay,
Thanks again for your comments, very helpful. Having looked carefully at Dave's new cropped image I see what you mean about the water droplet, the tick is interesting too. Shame about the material being hacked, because that would have been useful. I'm hoping to meet up with Dave and have a look for these birds in a week or so. My camera does record sound quite well so if I can get close I can probably get some half decent sound recordings, finding the birds is likely to be the problem I suspect.

Best regards,

Alastair