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
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