Saturday, 24 October 2009

Learning the Way of the Gull Master

Having been introduced to the delights or otherwise of birding at Didcot landfill/Appleford GP I've made two further trips there this week, mainly in order to continue in my quest to master the art of identifying Caspian gulls. As I have admitted previously in this blog I have found the whole herring/yellow-legged/caspian gull issue a bit or a challenge and I am determined to get the hang of it. To that end I have been diligently studying away, looking at photos and reading and re-reading whatever I can find on the internet in order to get it into my head and at last I seem to be making some progress. What has helped is the fact that at Appleford GP (which is the pool behind the level-crossing near the Didcot landfill) one can actually see the gulls at close quarters which is far easier than trying to make out distant blobs in your scope at the Farmoor roost. In the end of course there is no substitute for just looking at loads of gulls and I am pleased to say that after the two trips this week I definitely feel that I am getting there.

Mid week I went up one lunch-time for an extended lunch break and had a look around. Whilst there I thought that I found something which looked promising for one of the two first winter Caspian's that are currently around but it flew off before I was able to get a photo or a definite ID. I also realised that there were still some key identification issues which I wasn't sure on so I went back to my studies.

This Friday, fortified with what I hoped were the key points I went back again for an afternoon session. With the atlantis not having been seen for a couple of days now, visiting birders were getting thin on the ground so it was just myself and a couple of other birds present at the pit. Ian Lewington turned up at the far end and I gave him a quick call to say hello and to ask whether he'd come across any Caspians so far today but he'd just arrived. The chap next to me, who was a local birder whom I recognised from the day the white-winged black tern first turned up at Farmoor, having overheard my conversation pointed out what he thought was a Caspian gull on the far bank. I looked where he was indicating and found a classic adult yellow-legged gull, one could even clearly see it's bright yellow legs. This, and my recent experience of other birders mistaking a yellow-legged gull for a Caspian made me realise that there is a lot of confusion out there about this gull complex. I politely pointed out that it was a yellow-legged gull and just at that moment in front of it I spotted a white-headed gull which looked promising. I went through my mental check list for a first winter Caspian:
  • Tertials dark with thick pale tips. A notched pattern on the tertials means herring gull.
  • Greater coverts dark with pale tips to form a sort of wing bar pattern. At least there was no chequered pattern there which would be a herring gull deal breaker
  • Scapulars mid tone grey with small anchors in
  • Head clean white with long parallel-sided bill (though the bill wasn't as huge as on some cachinnans) and with a grey "shawl" around it's neck
  • A "kind" or elegantly aloof facial expression
More importantly it just looked right: somehow all the pouring over photos for hours was paying off and I was starting to acquire some sort of sense of the cachinnans jizz. I called up Ian opposite who had in the mean time found the same bird and he confirmed the ID. I spent the next couple of hours photographing the bird and various other gulls though the usual issues with photographing gulls came to the fore: autofocus on white birds is difficult and in any bright light the white bleaches out the photo if you're not careful (in future I must remember to reduce the exposure in such circumstances). I am finding that the easiest way to get some sort of shot is to video with scope and camera zoomed right in: the autofocus on the video means that some of the frames will be in reasonable enough focus for a videograb to be taken.

The 1st winter Caspian Gull. The pure white head is the most striking aspect but it needs the various other points to clinch the ID. The bright sunshine has rather bleached parts of this still shot.

A close-up still shot though unfortunately once again somewhat bleached out.
A videograb in overcast conditions shows the features better: note how elegant it looks compared to the other rather "brutish" gulls around it.
A first winter common gull on the shore

A first winter greater-black backed gull. Their bills are huge and really stand out from the crowd.

All in all a very enjoyable week getting to grips with gulls. I still have a long way to go: the adult and older immature birds are harder as there are less check points to go on so it comes down more to mantle tone and jizz unless one can get a clear view of the underwing but I fell that I'm definitely making good progress. It's also another tick for the county and national year lists.

Oxon County Year List 2009
183: Caspian Gull 23/10 Appleford GP

Nationsl Year List 2009
226: Caspian Gull 23/10 Appleford GP

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