Alan Dalton post's birding diaries and original artwork from Sweden. Established in 2006, this now long running blog is now a complete overview of my birding experiences. As an artist I greatly enjoy sketching birds in the field and you will find a wide selection of that work here, from fieldwork to finished paintings. I am very passionate about my artwork and try to depict birds in their natural habitat, as I see them in the wild. My artwork is for sale and can be viewed at http://www.alandalton.net/
As regards to my photography, since 2008 I have used a Nikon D90 DSLR camera coupled with a Sigma 150-500mm OS lens for since March 2012 for bird photography, all previous images being digiscoped. Regarding sound recording, I have been usung a Telinga Stereo Dat Mic and parabol to record birds in the field, coupled to a Marrantz 661 digital recorder, a superb piece of kit. Interest in butterflies, dragonflies and damselflies has recently seen the accquisition of a Sigma 150mm macro lens. I hope you enjoy the blog and please feel free to leave comments or contact me at alandltn@gmail.com

Wednesday, August 06, 2014

Caspian Gull; 3rd Calender Plumage; Skeppsbron; 6th August 2014

Note here the small head, long parallel sided bill, small dark Eye, high chested appearance. The tibia were noticably long, in direct comparison to Herring Gull, the bird looked noticably longer legged on land. Aged by second generation P7-P10, as well as second generation covert's.


The small dark eye and thin red orbital ring can be seen here, as well as the long, parallel sided bill with rather reduced gonydeal angle. Small, diffuse dark markings near the bill tip help age the bird. Note the long necked appearance here and second generation covert's...


Note here the rather long legged appearance of the bird, a striking bird on the deck.. The legs were pink.


Here the bird looked rather less attentuated at the rear, with perhaps a shorter primary projection than might be expected of Caspian Gull? The long tibia and high chested look are again apparent in this photo..

Again here, the bird looking very long necked. On the water the bird was still striking and stood out from nearby Herring Gulls, though again there is a rather less attentuated rear than might be expected. The small dark eye and profile of the head and bill was rather consistent and allowed the bird to be easily picked out.


 
The open wing here showing P5 has grown out, showing only a small dark wedge, not a complete dark sub terminal band. This is not textbook and suggests this may not be a pure Caspian Gull and may point to some Herring genes. The tail is also atypical for third calender Caspian Gull, if within variation, the dark tail marking are diffuse. Note the second generation P8-P9. It seems P6-P7 have been dropped, whilst P1-P5 are new, third generation feathers.


The bird twisting in flight, allowing a superb view of the tail. The tail band is very diffuse indeed and whilst within the variation of Caspian Gull, it would be considered more typical of Herring Gull and may also lead to doubts as to whether this bird has not got some Herring Gull genes, particularily when the small dark wedge on P5 is considered.


The underwing here show faint brown traces, again not textbook Caspian at this age. Again, the lack of a complete dark subterminal band on P5 is the key feature overall, the small dark wedge present can be seen on the far upperwing here.

My regular daily checks of the gulls at the site continued today. I had been onsite for around 40 minutes and had been feeding bread for around ten minutes when I fisrt noticed this bird after it flew in and landed on the water. The long, parallell sided bill, small dark eye and head shape immediately flagged the bird, which I soon managed to coax onto the dockside with bread. On land the bird was even more striking, displaying a remarkably long legged appearance due to the long tibia. I spent about 40 minutes observing the bird, carefully noting all the features discussed above. The bird ticked a lot of boxes with regard to identification as Caspian Gull, certainly looking the part structurally. The jizz in particular was striking, the birds small headed appearance, combined with high chest, long legs and general carriage. It was slightly smaller than the Herring Gulls present and constantly recalled Common Gull in many ways, due to the appearance of the clean white head, small dark eye and the facial appearance. The small dark wedge on P5 was noted in the field, something which did not bother me at the time as I thought it might be within variation for the species, such was the overall impression of the bird. It was only later on, when the photos were processed and posted that full consideration was given. Comments on the bird were forthcoming from Peter Adriens and Jan Jorgensen in particular, who expressed concerns as to the marking on P5 in particular. The diffuse tail markings were more of a minor concern as they fell within variation for the species. However, when taken into consideration, the absence of a full subterminal band on the fifth primary, combined with diffuse tail band, lead to doubts as to whether this is a pure Caspian Gull.
 Naturally, Stockholm is on the northwestern edge of this birds occurance and as such is close to the more western breeding colonies of Caspian Gull, where hybrids are well documented, particularily in Poland amongst other countries. It is to be expected that some birds of mixed genetic parentage can and do occur, making identification fraught at times. It seems that this bird is likely not to be a pure Caspian Gull, all features taken into account. For me. personally, this remains a stunning gull and the probability of the bird not being a pure Cachinans does not detract from the experience. I think at times, the need for observations to have to fit neatly into a species bracket can stifle birding experience and not every bird is assignable to category. That's fine. Not every bird falls into the bracket of a slam dunk identification, and whilst a textbook, easy individual is always welcome, birds like these help further knowledge. So, Caspian Gull proceeded by a full stop? No it's not. Caspian Gull proceeded by a question mark? Yes, it surely is. Does it really matter?
I would like to thank Peter Adrians and Jan J├Ârgensen for their invaluable help and expertise with regard to this bird.

3 comments:

Anonymous said...

Superb pictures for an exciting bird Alan! It was nice to see you again there at Skeppsbron! Thanks for showing me the bird! Dirk Van Gansberghe.

Alan Dalton said...
This comment has been removed by the author.
Alan Dalton said...

Thanks Dirk, was very happy to see you onsite and that the bird reappeared a second time, which allowed me to get the open wing shots. See you at Skeppsbron soon.
Alan.