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Cornish gull i.d. please (1 Viewer)
- Thread starter CJW
- Start date
Charles Harper
Régisseur
Welcome back, gentlemen.
Cuckoo-shrike
Well-known member
Well CJW I'm no gull expert and I've not seen Caspian, but for starters, from the pics I've seen they have a very distinctive slender bill and a "snout" effect like an Audouin's. This bird's bill is surely too heavy.
There's really no short answers with gulls but very briefly this is a mich rather than a cach because (in no particular order):
1) what is visible of the greater and medians reveals a pattern of dark centres and irregularly shaped (notched) pale edges without any real pattern of contrasting pale tips forming pale wingbars. On cach the greater coverts in particular show a plainer or streakier pattern with neater pale fringes and diffuse pale tips which show up as quite a prominent pale wingbar in most birds. On swimming birds all but the inner third or so of the coverts are hidden by the flanks so this must be used rather carefully but there's enough visible in the first pic to rule out cach.
2) The bill is much heavier than that of most cach, has a prominent gonydeal point and and a rather steep culmen at the tip, the shape is somewhat reminiscent of a GBBG. On Casp the bill is finer, lacks such a prominent gonydeal point and has a more gently curved tip. To draw a rather extreme analogy (with Herring and LBBG viewed as comparable to a Common Gulls) cach looks more like a Slender-billed or Black-headed Gulls and mich more like a Med Gull.
3) relatively few cach are as worn as this in October, indeed such wear on the coverts and tertials at this date is very typical only of mich.
4) Most cach have much whiter head and body plumage than this bird and tend to have streaking concentrating on the hindneck and upper breast sides to create quite a striking shawl effect, cach rarely show such a concentration of streaking around the eye and the whole head often looks very white with a rather small dark eye looking somewhat isolated.
5) cach typically shows a more snouty appearance with a particularly long and shallow looking forehead that can again bring Slender-billed Gull to mind. The 'dignified' or 'proud' head structure of this bird is very typical of mich and most unlike the overwhelming majority of cach.
6) cach frequently shows less obvious dark markings in the scapulars so that the grey component in these feathers is even more obvious than on mich (though both show a contrast of grey scaps versus brown coverts and whitish head and underparts which tends to set them apart form Herring and LBBG of comparable age, the latter being more uniformly toned lack this tri-coloured pattern)
here's some links,
cach in October:
http://www.xs4all.nl/~calidris/caspianHL.htm
http://www.martinreid.com/cachp03.html
and November:
http://www.xs4all.nl/~calidris/Pontic3.htm
and December:
http://www.xs4all.nl/~calidris/PonticDec.htm
Some mich,
nice comparison with Herring in Jan (note more heavily worn plumage of mich on left and that it has replaced some coverts - very rare in Herring), top image:
http://oystman.tripod.com/italiangulls/id9.html
November:
http://www.magikcircle.com/birds/image.asp?title_id=459&show_thumbnails=False
A fresher plumaged bird in Aug, still with a few retained juvenile rear scapulars:
http://www.magikcircle.com/birds/image.asp?title_id=811&show_thumbnails=False
Another in November (unusually fresh for this date):
http://www.magikcircle.com/birds/image.asp?title_id=465&show_thumbnails=False
October (rather herring gull like head pattern but otherwise typical):
http://www.martinreid.com/michp04.html
Another October bird (note the replaced coverts - some cach are similar but very few Herring ever replace coverts or tertials in autumn)
http://www.martinreid.com/michp03.html
A view of the open wing would be totally conclusive but I can't see anything on this bird to point to cach and plenty that points to mich.
Unfortunately the best European gull website has been unavailable for some months now.
Spud
1) what is visible of the greater and medians reveals a pattern of dark centres and irregularly shaped (notched) pale edges without any real pattern of contrasting pale tips forming pale wingbars. On cach the greater coverts in particular show a plainer or streakier pattern with neater pale fringes and diffuse pale tips which show up as quite a prominent pale wingbar in most birds. On swimming birds all but the inner third or so of the coverts are hidden by the flanks so this must be used rather carefully but there's enough visible in the first pic to rule out cach.
2) The bill is much heavier than that of most cach, has a prominent gonydeal point and and a rather steep culmen at the tip, the shape is somewhat reminiscent of a GBBG. On Casp the bill is finer, lacks such a prominent gonydeal point and has a more gently curved tip. To draw a rather extreme analogy (with Herring and LBBG viewed as comparable to a Common Gulls) cach looks more like a Slender-billed or Black-headed Gulls and mich more like a Med Gull.
3) relatively few cach are as worn as this in October, indeed such wear on the coverts and tertials at this date is very typical only of mich.
4) Most cach have much whiter head and body plumage than this bird and tend to have streaking concentrating on the hindneck and upper breast sides to create quite a striking shawl effect, cach rarely show such a concentration of streaking around the eye and the whole head often looks very white with a rather small dark eye looking somewhat isolated.
5) cach typically shows a more snouty appearance with a particularly long and shallow looking forehead that can again bring Slender-billed Gull to mind. The 'dignified' or 'proud' head structure of this bird is very typical of mich and most unlike the overwhelming majority of cach.
6) cach frequently shows less obvious dark markings in the scapulars so that the grey component in these feathers is even more obvious than on mich (though both show a contrast of grey scaps versus brown coverts and whitish head and underparts which tends to set them apart form Herring and LBBG of comparable age, the latter being more uniformly toned lack this tri-coloured pattern)
here's some links,
cach in October:
http://www.xs4all.nl/~calidris/caspianHL.htm
http://www.martinreid.com/cachp03.html
and November:
http://www.xs4all.nl/~calidris/Pontic3.htm
and December:
http://www.xs4all.nl/~calidris/PonticDec.htm
Some mich,
nice comparison with Herring in Jan (note more heavily worn plumage of mich on left and that it has replaced some coverts - very rare in Herring), top image:
http://oystman.tripod.com/italiangulls/id9.html
November:
http://www.magikcircle.com/birds/image.asp?title_id=459&show_thumbnails=False
A fresher plumaged bird in Aug, still with a few retained juvenile rear scapulars:
http://www.magikcircle.com/birds/image.asp?title_id=811&show_thumbnails=False
Another in November (unusually fresh for this date):
http://www.magikcircle.com/birds/image.asp?title_id=465&show_thumbnails=False
October (rather herring gull like head pattern but otherwise typical):
http://www.martinreid.com/michp04.html
Another October bird (note the replaced coverts - some cach are similar but very few Herring ever replace coverts or tertials in autumn)
http://www.martinreid.com/michp03.html
A view of the open wing would be totally conclusive but I can't see anything on this bird to point to cach and plenty that points to mich.
Unfortunately the best European gull website has been unavailable for some months now.
Spud
Hi Spud,
A masterful summary of differences between 1st-year michahellis and cachinnans!
I fear that,despite my interest in gulls(and the fact that I can see why it's a mich from the photos),I'd have overlooked this as a Herring Gull(argenteus)in the field:I have seen presumed argenteus that show some of the features of this bird(though probably not all).1st-year michahellis seem to be genuinely scarce in Ireland(considering that they make up a large proportion of British records),and,as a result,it is very difficult to build up confidence in identifying them(I have never been able to clinch a YL Gull of this age here,despite having seen lots in Bulgaria).Lacking this confidence,it is all too easy to assume that such birds are just odd Herring and leave it at that.
I have no such problems with michahellis once they gain some adult-type mantle feathers,and remember seeing the retained "1st-w" remiges of a 2nd-cal bird when it flew and commenting on how typical they were for mich(as was the tail pattern),so this mental block with regard to 1st-early 2nd cal birds is frustrating!Having said that,I have seen very few birds that I felt may have been mich of this age group!
Harry H
A masterful summary of differences between 1st-year michahellis and cachinnans!
I fear that,despite my interest in gulls(and the fact that I can see why it's a mich from the photos),I'd have overlooked this as a Herring Gull(argenteus)in the field:I have seen presumed argenteus that show some of the features of this bird(though probably not all).1st-year michahellis seem to be genuinely scarce in Ireland(considering that they make up a large proportion of British records),and,as a result,it is very difficult to build up confidence in identifying them(I have never been able to clinch a YL Gull of this age here,despite having seen lots in Bulgaria).Lacking this confidence,it is all too easy to assume that such birds are just odd Herring and leave it at that.
I have no such problems with michahellis once they gain some adult-type mantle feathers,and remember seeing the retained "1st-w" remiges of a 2nd-cal bird when it flew and commenting on how typical they were for mich(as was the tail pattern),so this mental block with regard to 1st-early 2nd cal birds is frustrating!Having said that,I have seen very few birds that I felt may have been mich of this age group!
Harry H
Brian Stone
A Stone chatting
I know what you mean Harry. Yesterday I saw a bird very similar to the one pictured, loafing in a field with other gulls near Peterborough. It was the tertials that helped ruled out Herring Gull for me. These are almost solidly dark with just neat pale fringes near the tip. Please correct if I am wrong but Herring Gulls have tertials notched with white along one edge.
graellsii has similarly dark tertails but wouldn't show the pale mantle and scapular feathers. Again, please correct if I am talking rubbish, I am still very much learning and I am just as happy discussing why this isn't a Herring or LBB Gull as why it isn't a Caspian.
graellsii has similarly dark tertails but wouldn't show the pale mantle and scapular feathers. Again, please correct if I am talking rubbish, I am still very much learning and I am just as happy discussing why this isn't a Herring or LBB Gull as why it isn't a Caspian.
Thanks for the excellent summary and links spud. I'm still wondering about the legs on the bird in the photograph. This is not in a bid to reconsider its identification but they do look quite long and also rather thin. Possibly this later point is an effect of the camera and the angle of the bird but (to someone with my very limited knowledfe) it does lend the bird at least the suggestion of Caspian Gull from the belly down. I'd be interested to know what differences there are in the leg structure of cach and mich (in comparison to Herring and LBB as well).
Oh by the way Harry - I can't find any YLG's round my way either. Puzzling really and quite frustrating. They seem to be all over the place when I go down south but I don't do that often enough to build up experience and confidence with them, especially youngsters.
Oh by the way Harry - I can't find any YLG's round my way either. Puzzling really and quite frustrating. They seem to be all over the place when I go down south but I don't do that often enough to build up experience and confidence with them, especially youngsters.
Without boring everyone with lots of minutiae I'd particularly draw attention to the state of the plumage of 1st-y mich versus either Herring or LBBG in autumn. The breeding and fledging dates of mich are a month or more earlier than those of the other two and the progression to first-winter plumage is consequently early too, mich starts to moult into 1st-w plumage as early as late July while UK Herrings don't start till late August or later and LBBG often even later still.
In mid October almost all healthy Herring and LBBG are in pristine plumage still and while many have replaced all of their juvenile scapulars some still retain some (in fact some Arctic reared Herring are still in full juvenile plumage in Dec or later).
Mich. by comparison, is normally in full first-w plumage by early Oct and conspicuously worn on the tertials and wing coverts by mid October. Presumably as an adaptation to this increased level of wear mich regularly show some replaced inner coverts and tertials before November. These replaced feathers are similar in pattern to the new grey based and dark barred scapulars and contrast strongly with the adjacent worn brown feathers.
Even on those birds which do not show this characteristic moult contrast the level of wear is nomally still striking, especially as it makes the pale areas on the coverts less conspicuous so that the brownness of these feathers is in even more stark contrast to the grey tones of the fresh 2nd generation scapulars. These scapulars tend to show a relatively narrow dark subterminal area and a fine shaft streak joining this to the dark bar at the base of each feather, this leaves large clear pale grey areas either side of the shaft which create the overall grey tone of scaps.
By comparison the scapulars on Herring are more heavily marked with dark so that the wider dark subterminal areas on the feathers align with each other or with the dark basal bars on adjacent feathers to produce an impression of barring across the scapulars - something hardly shown in mich. which looks more scaly or checkered.
Also because the wing coverts of Herring are less worn (perhaps they are of better quality to begin with?) and because the pale areas in the scaps are less extensive and less pure grey there is less of a contrast between the brown coverts and grey scapulars generally.
CJW's mich shows a couple of scapulars with a slight cinnamon wash which is probably never shown by Herring but is not uncommon in mich.
It is very normal for mich to show such long legs though this has often be stressed as a feature of cach. I wonder whether the long legs described for cach are mentioned only in relation to Herring, which has the short fat legs typical of gulls from rocky coastlines, or whether the long (and often skinny looking) legs of cach particularly catch the eye because of the somewhat upright stance of that species. One of the reasons the legs look unusually thin in the above pic is because they are being viewed from the front rather than the side.
Some LBBG may show very long legs too but LBBG never shows such pale scaps in 1st-w plumage and normally looks even fresher than Herring at comparable dates.
I could go on and on (wing and tail patterns etc) but wont as such features are reasonably well covered in the literature, eg the Collins Guide.
One secret of immature large gull identification is to take the plumage as seriously as that of, say, juvenile calidris sandpipers...all the clues are there but few people have really bothered to look for them in the past. 1st-years are often easier to identify than adults in my view as they show many more clues.
Spud
In mid October almost all healthy Herring and LBBG are in pristine plumage still and while many have replaced all of their juvenile scapulars some still retain some (in fact some Arctic reared Herring are still in full juvenile plumage in Dec or later).
Mich. by comparison, is normally in full first-w plumage by early Oct and conspicuously worn on the tertials and wing coverts by mid October. Presumably as an adaptation to this increased level of wear mich regularly show some replaced inner coverts and tertials before November. These replaced feathers are similar in pattern to the new grey based and dark barred scapulars and contrast strongly with the adjacent worn brown feathers.
Even on those birds which do not show this characteristic moult contrast the level of wear is nomally still striking, especially as it makes the pale areas on the coverts less conspicuous so that the brownness of these feathers is in even more stark contrast to the grey tones of the fresh 2nd generation scapulars. These scapulars tend to show a relatively narrow dark subterminal area and a fine shaft streak joining this to the dark bar at the base of each feather, this leaves large clear pale grey areas either side of the shaft which create the overall grey tone of scaps.
By comparison the scapulars on Herring are more heavily marked with dark so that the wider dark subterminal areas on the feathers align with each other or with the dark basal bars on adjacent feathers to produce an impression of barring across the scapulars - something hardly shown in mich. which looks more scaly or checkered.
Also because the wing coverts of Herring are less worn (perhaps they are of better quality to begin with?) and because the pale areas in the scaps are less extensive and less pure grey there is less of a contrast between the brown coverts and grey scapulars generally.
CJW's mich shows a couple of scapulars with a slight cinnamon wash which is probably never shown by Herring but is not uncommon in mich.
It is very normal for mich to show such long legs though this has often be stressed as a feature of cach. I wonder whether the long legs described for cach are mentioned only in relation to Herring, which has the short fat legs typical of gulls from rocky coastlines, or whether the long (and often skinny looking) legs of cach particularly catch the eye because of the somewhat upright stance of that species. One of the reasons the legs look unusually thin in the above pic is because they are being viewed from the front rather than the side.
Some LBBG may show very long legs too but LBBG never shows such pale scaps in 1st-w plumage and normally looks even fresher than Herring at comparable dates.
I could go on and on (wing and tail patterns etc) but wont as such features are reasonably well covered in the literature, eg the Collins Guide.
One secret of immature large gull identification is to take the plumage as seriously as that of, say, juvenile calidris sandpipers...all the clues are there but few people have really bothered to look for them in the past. 1st-years are often easier to identify than adults in my view as they show many more clues.
Spud
Hi all,
Fifebirder:"Oh by the way Harry - I can't find any YLG's round my way either. Puzzling really and quite frustrating. They seem to be all over the place when I go down south but I don't do that often enough to build up experience and confidence with them, especially youngsters."
While the scarcity of michahellis is perhaps to be expected in Fife,one would have imagined that they would be tolerably regular in southern Ireland.As it happens,the taxon was removed from the list of those requiring a description by the IRBC back in early 2000,but since the downsizing of many municipal dumps(including good old Cork city dump!),it is getting hard to find one:indeed,I haven't seen one since March 2002,and that was my only sighting that year!
I would guess that they are still turning up as regularly as in the mid/late 90's,but are harder to find due to the lack of decent concentrations of large gulls in relatively small areas?
Spud:while I agree(based on photographic evidence)that 1st-year large gulls can be easier to ID than adults in at least some taxa(cachinnans and thayeri stand out!),I would hesitate to say the same about michahellis.I see candidates most winters for 1st-year mich,but to date have been unable to clinch any of them!
Some have proved on closer examination to be argenteus/argentatus,but,of course,some may well have been mich....Just have to knuckle down to it this winter,if I can find any decent gull site!
Harry H
Fifebirder:"Oh by the way Harry - I can't find any YLG's round my way either. Puzzling really and quite frustrating. They seem to be all over the place when I go down south but I don't do that often enough to build up experience and confidence with them, especially youngsters."
While the scarcity of michahellis is perhaps to be expected in Fife,one would have imagined that they would be tolerably regular in southern Ireland.As it happens,the taxon was removed from the list of those requiring a description by the IRBC back in early 2000,but since the downsizing of many municipal dumps(including good old Cork city dump!),it is getting hard to find one:indeed,I haven't seen one since March 2002,and that was my only sighting that year!
I would guess that they are still turning up as regularly as in the mid/late 90's,but are harder to find due to the lack of decent concentrations of large gulls in relatively small areas?
Spud:while I agree(based on photographic evidence)that 1st-year large gulls can be easier to ID than adults in at least some taxa(cachinnans and thayeri stand out!),I would hesitate to say the same about michahellis.I see candidates most winters for 1st-year mich,but to date have been unable to clinch any of them!
Some have proved on closer examination to be argenteus/argentatus,but,of course,some may well have been mich....Just have to knuckle down to it this winter,if I can find any decent gull site!
Harry H
