BIRD GUIDING AROUND OSLO

Tuesday, 11 February 2014

Breaking my rules


News leaked out yesterday evening of a Caspian Gull (kaspimåke) seen in Fredrikstad first on Sunday and then again yesterday. I wasn’t sure as to whether to go for it today given that 1.) it would mean twitching, 2.) an hour and a half drive, 3.) it was a gull and 4.) it was dangerously close to The Great Big Dump, Øra. I awoke in a particularly positive frame of mind though and thought what the heck. After getting the girls off to school and kindergarten I headed south. I was not happy about the heavy rain which as usual didn’t correspond with what the weather forecast from yr.no was telling me it should be but as I approached Fredrikstad it dried up.

The bird had been seen in Gamlebyen which is the old fortified town at Fredrikstad (one of precious few such historical fortresses in Norway) and as I made my way through the cobbled streets and parked by the river I saw there was another birder present. It was, as I suspected, Eirik Grønningsæter who is attempting to break the Norwegian year list record and had left Trondheim at 2am to get here (see his Big Year blog on my blog list). We stood there, threw out bread, scanned the gulls, chatted with a couple of other birders who popped in (including finder Asgeir Larsen), stood there some more, scanned some more, chatted some more, threw some more bread and three hours passed so quickly (not!). There were around 100 Herring Gulls in the area but there was little movement (there were most likely another 1000 just down river at the Great Big Dump). It is amazing how little gulls do during the course of the day and they were also not so interested in the bread we threw out to them (although the bread old ladies had to offer was scoffed up) and it is a wonder they get enough food. As you guess though the bird in question didn’t turn up (although it is still in the areas a unfortunately late report came in after dark that it had been seen at the Great Big Dump).

If you pay enough attention to large gulls you always find some odd ones and there were a couple that stood out today. Norway has a handful of experienced and knowledgeable larophobes and they are split into two “schools” (or they are by me at least): the Eastern (ES) and Western Schools (WS). From what I can see they differ in their teachings (and both schools have their disciples) by how they deal with non classic specimens. For the ES it would appear that anything odd that can’t be placed with safety in a bucket gets called a “presumed Herring Gull” with Herring Gull being the default as it is the commonest large gull in Norway. The WS however seems to prefer to use other labels for atypical birds and one particular type of bird causes a lot of debate namely the “Bergenshybrid” which to the ES is a pale extreme of Herring Gull whereas to the WS are hybrids (though not necessarily 1st generation) between Herring and Glaucous Gulls. I have spoken (tediously and at length) about these birds before and today there was a nice example of such a bird (pictured below). Personally I’m not really sure how to classify these birds but tend towards them being “just” pale Herring Gulls because they seem to be so regular in the south whereas Glaucous remain a real rarity such that I can't understand where all these birds would originate if they were really hybrids.

On the other hand there are a number of other birds that the ES label as “presumed Herring” which show great similarity to Caspian and Yellow-legged Gulls and for which I believe it is wrong to not try to put another label on as they push the boundaries of what a Herring Gull looks like and is I think far too simplistic (to put in at another way there is no way these birds would be accepted as vagrant Herring Gulls in Southern Europe). We had one such gull today (pictured below) which for me had a lot of Caspian features although was far from ticking all the boxes. However, it was also outside what I would expect a Herring Gull to look like  – it could well be a hybrid which seem to be fairly regular in many mixed colonies in Poland and neighbouring countries. This particular bird bore a colour ring allowing part of its life history to be found at the few clicks of a mouse. This bird was ringed in Oslo on 4th September 2012 as a Herring Gull in its 2nd cy (i.e was over a year old). On 4th November it was 261 km away in Hirtshals in Denmark before returning north on 23rd November to Moss (only 50km from Oslo) when it had the misfortune to be trapped again. It was then seen in Fredrikstad on 31.12.2013 before my sighting today.

When you stand in the same place for three hours you see or hear a few other birds and we heard a migrating Skylark (sanglerke) which is my earliest Norwegian spring bird by a long way. On my drive home I had three roadside Great Grey Shrikes which is back to the expected level after a couple of quiet months and could also well be a result of spring migration having already started for this species. A well timed stop to expel excess liquid also revealed calling Bearded Tits at Sorgenfrigropa.

Extreme, pale Herring Gull aka "Bergenshybrid", alternatively Herring x Glaucous Gull Hybrid (2cy)

note the pale wing with the outer primaries being the same brown colour as the darkest feathers elsewhere on the wing.

Here are three birds of the same age (2 cy) with the rear two being normal Herring Gulls. Note how on the paler bird the white edges to all the wing feathers are much broader creating a much paler impression

the pale bird is on the left. In addition note the broad pale edges to the primaries
 Unidentified large gull with possible Caspian Gull genes (3cy)
 
the colour ring "JU2E" has allowed me to see some of this gulls life history and it was ringed as a Herring Gull with no special note made by the ringers.  Note the white head, breast and underparts and grey "shawl". This bird had a distinctive jizz with long wings held low as well as a drooping tail

here with 5 Herring Gulls note the difference in jizz with droping tail and wings plus the different head shape.

a Caspian Gull should show dark greater coverts and tertials whereas this bird has peculiarly pale ones

the tail band is not dark enough and without a clear cut boundary to a white rump


Also two birds that I do consider to be within the range for Herring Gull although both stood out.

Yellow(ish) legged adult Herring Gull
this birds legs had a yellowish tinge.  Note also the almost orange bill which stood out compared to all the other adult Herring Gulls.

The primary pattern doesn't suit a real Yellow-legged Gull and it also had an orange rather than red eye ring so this bird is most likely just within the range of Herring Gull
 Green legged adult Herring Gull
this bird stood out with a slightly long winged and upright jizz and the green legs are more appropriate for Caspian than Herring Gull but there was nothing else particularly unusual about this bird (although I never saw it in flight)

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