Friday, 21 March 2014

Gulls, Gulls, Gulls

The Rise and Rise of Cachinnans

Over the last couple of winters I have made Milton my local patch in an attempt to learn more about gulls. The refuse tip attracts large numbers and recently Caspian gull has chosen this site as one of its favoured British overwintering locations - at times Milton has been THE best spot to see Caspian gull in Britain and being less than 20 minutes from my home it's a convenient spot to watch. A few weeks back there were 10 gull species regularly visiting, though the most I managed in a day was 9.

 Dick Newell has photographed many Caspian gulls in the wider area (see but my first few attempts at locating them were largely unsuccessful. I found an adult beside the A10 at Landbeach in 2005 but any others were generally only possibles or probables and I found adult argentatus (Scandanavian herring) in particular to be at times tricky to rule out. They can be large, just as dark above and have a very similar primary pattern to Caspian.

Then about 3 years ago I found a distinctive first winter on the tip. I had only made a handful of trips at this time and it seemed to be a pivotal point as thereafter I started to come across more of them. Part of it may have been related to 'getting my eye in' but then again I had seen a number of Caspians previously elsewhere round the country, including a first year in Norfolk.

Caspian gull (1st yr), Milton Tip, Jan 2011. Classic and striking bird and in view all too briefly as they often are in the feeding mellee on the tip.
 I started concentrating on Milton (rather than Landbeach or Cottenham) soon afterwards and found Caspians to be constantly present in small numbers. I think at the same time some other landfill sites may have closed as the overall number of gulls here seemed to increase around this time. But they are recorded everywhere more regularly these days with birders knowing what to look for and with their range expanding westward into Central Europe, though they remain very rare in Scotland, Wales and Ireland. Many are seen  in particular in the Thames Valley/ Estuary where photographs of ringed individuals have enabled observers to trace their movement history and country of origin.

I usually see 2 - 4 individuals on a winter visit to Milton and sometimes as many as 5 (though I usually miss out on the ringed birds!). Others have seen 7 or 8 in a day and there was one day when 9 different birds were seen (with the combined efforts of several birders). The only British gathering I know of which surpasses that number is the 11 seen at Dungeness in December 2013 and certainly this number of individuals has been recorded at Milton over a long weekend.

Caspian gull is a favourite among Larophiles as at a site like this it gives you something to look for (while hoping for something rarer) which is likely to be actually present. They can be very handsome and elegant in appearance - sometimes striking, sometimes more subtle. And anyone birding in the nineties will remember that not so long ago they were not known about - It was 1996 a ground-breaking paper appeared in British Birds alerting us all to their presence, based on the documentation of birds present at Mucking Tip in Essex. Within a couple of years we were all out looking for them; they were known as Pontic gull, or sometimes as Eastern yellow-legged as they had not yet been split from Western. It was a number of years before BOU finally made the change after what was a considerable delay, even for them, but gull taxonomy is tricky and decisions are often left for years pending scientific research.

Anyway, here's a gallery of Casps, followed by a few other gulls of interest. Most of the pics are taken at Milton but some later on were taken in Scotland. I don't have access to the tip at Milton so the birds are sometimes distant (apologies for the poor quality of some pics!), particularly as their favourite field (bordered by Butt Lane & the A10 just by Milton Park & Ride) is the size of a small county! I have used the old age class system (1st winter, 2nd winter, etc as opposed to x calendar year) for ease, though it's a little crude in the context of gull moult which does not like to be pigeonholed in this way!

1st year

1st winter Caspian gull, Milton Tip, Jan 2014. Rather large, dark bird with distinctive bill pattern. Note ad YLG below to the right

1st winter Caspian gull, Freckenham, Jan 2014. Large, classic, striking bird with c150 gulls beside the A11

1st winter Caspian gull, Milton Tip, March 2014
1st winter Caspian gull, Milton Tip, Nov 2012 (with presumed 4th winter argentatus herring gull). Caspian gull moults earlier than herring, but this bird is exceptionally advanced, showing moult contrast in the scaps and coverts (2nd & 3rd gen) in November; normally this moult would commence the following spring or summer but this bird has already replaced its lower row of scapulars. It shows off the beautiful grey shawl of streaking superbly. It is standing in the shade of the bank which gives a good flat light for assessing colours and shades. Bright sunshine can make it very difficult picking out subtleties.

1st winter Caspian gulls, Milton, Jan 2013. I was photographing the preening bird at the back (here showing the tail pattern nicely) and only noticed the front bird later on when examining photos. It hadn't been present at the start but had 'photobombed' the image.
  2nd yr

2nd winter Caspian gull, Milton Tip, Jan 2014. As well as the obvious bird centre left, the bird in the middle at the extreme right is also a 2nd winter Caspian, albeit a rather camera-shy one!

2nd winter Caspian gull, Milton, Jan 2014. Though the mantle looks a bit pale here, it looked fine in the field with all relevant features present. Note very long wings giving the bird an attenuated, phalarope-like rear end.

2nd winter Caspian gull (or hybrid), Milton , Jan 2013. I had this down as a cachinanns x argentatus hybrid for a long time but believe now it could well be within variation of Caspian gull. It shows a rather heavy bill and unusually short, thick legs for this species.

3rd yr
3rd winter Caspian gull, Milton Tip, Jan 2013. Like many subadult Caspians this bird retains traces of streaking on the nape, all that is left of the distinctive 'grey shawl' so obvious in its first year. Similar to adult, but note dark tertials and primary coverts (and sometimes dark slivers on the tail)


Adult Caspian gull, Milton Tip, Nov 2012. P10 underside just visible

Adult Caspian gull, Histon, Feb 2014. Dark eye and small head obvious here, giving the bird a rather common gull-like appearance. One of three birds in this particular flock in a flooded field a couple of miles from Milton Tip.

Caspian gulls, Milton, Feb 2014. This photo shows (at the front of the flock) a 3rd winter and an adult Caspian gull but they're far from obvious. I was trying to make up my mind on the younger bird when it gave the diagnostic long call (a first for me) starting with wings raised for the start, then folded with head thrown back 90 degrees (typically 45 on herring and wings not raised). It was posturing and squaring up to the adult which I'd overlooked - not an obvious bird (at a fair range admitedly) but I suddenly realised it was identical structurally to the 3rd winter and appeared dark-eyed with the right head shape and a longish bill (rather bright, indicating full breeding getup). In this photo only the long wings seem to stand out though the dark eye is hinted at too. But whereas the previous adult bird leapt out at me (so to speak), this one did not.

Other species

1st winter Glaucous gull, Milton, Jan 2013. Small bird and very pale, appearing almost white in the field. Superficially similar to a 2nd winter, it is actually a 1st winter, showing a dark eye and solid dark bill tip. The coloration is not down to wear but thought to be due to racial variation or colour morphing - white birds like this seem to be commoner to the west of the species' range.

1st winter Glaucous gull, Milton, December 2012. A large, dark bird (even recalling American herring in this pic) in contrast to the previous one, though note it usually looked paler in the field than is suggested in this photo
1st winter Glaucous gull, Milton, January 2014. Dwarfing a colour ringed LBBG

1st winter Glaucous gull, Milton, January 2014. Same bird as above
Gulls, Milton Tip, Feb 2014. There are 6 spp in this pic - can you spot the Caspian & glaucous?

1st winter Glaucous gull, Milton Tip, January 2014. Same bird as above
Adult yellow-legged gull, Milton Tip, November 2012. Always present in small numbers, with adults and older immatures most numerous; 1st winters rather scarce

Hybrids and other confusing individuals
Hybrid gull resembling adult Iceland gull, Milton Tip, January 2014. This bird showed grey on the leading edge of the primaries and very herring gull-like head and bill plus rather long legs. It could be a Viking type, (Glaucous x herring hybrid, rather common in northern latitudes) but the long wings are puzzling. We're told Iceland very rarely hybridises, but could this bird have had L glaucoides as one of its parents?

2nd winter Iceland gull or hybrid, Collieston, Aberdeens, December 2013. Not taken anywhere near Milton, this was the other interesting gull of the winter for me. It bears some similarities to the previous bird, hence its inclusion here, in that it appears to lie on or near the edge of the expected range of variation of Iceland gull but its true identity is not clear. It could be a 'Viking' gull, an exceptionally dark Iceland-type or an Iceland x herring hybrid. After seeing the last two birds, I'm left wondering if perhaps it's worth reconsidering the apparent rarity of Iceland hybrids?

2nd winter Iceland gull sp or hybrid, Collieston, Aberdeens, December 2013. Pale eye, rather heavy bill and slightly atypical primary pattern are among the featues seemingly at odds with my original identification of this bird as a 2nd winter Kumlien's gull. 
1st winter Caspian gull or hybrid, Milton Tip, March 2014. This bird took flight with the flock and I only got a couple of (very poor) shots. Looking at them later it's apparent there is dark blackish feathering coming through on the outer coverts around the carpal joint and on the scapulars. It doesn't look like oil or any other kind of soiling and looks too dark to me to be misrepresentative photo artefact, but rather some dark LBBG-like 3rd gen feathering, yet it looks too large, pale and long-legged for a nominate fuscus and looks otherwise to be a Caspian-type.
Adult lesser black-backed gull or hybrid (possibly with herring or GBBG) Figgate Park, Edinburgh, March 2014. An unusual bird for a lesser with very broad white trailing edge, pale pink legs and shortish primary projection. A number of apparent herring x LBBG hybrids have been photographed in this area and as some hybrids can adopt the upperpart coloration of one parent (rather than appear intermediate) it's just possible there could be herring gull genes in this bird. However it could still be within the range of LBBG - would welcome further opinion on this.
1st winter Ivory gull, Patrington Haven, Yorks; December 2013. The best gull of the winter and part of a record influx, added here to prove to Larophobes that gulls (even young ones) can be simple, straightforward and beautiful- sometimes!

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