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Immature gull, Castilla-La Mancha, Spain (1 Viewer)
- Thread starter xrxss15
- Start date
lou salomon
the birdonist
it's a 2cy black-headed gull. bill colour in immatures quite variable.
lou salomon
the birdonist
no, with its "first summer" after the year it was hatched, so, at this age "2nd winter" follows.
Nutcracker
Stop Brexit!
Yep, first summer starting moult to second winter.
Not sure why use this 'cy' thing, it's confusing and a lot less precise - and can have very peculiar effects, if you have two sibling chicks in a nest hatched on 31 December and 1 January respectively, one would be "1 cy", the other "2 cy" despite being the same plumage :eek!:
Not sure why use this 'cy' thing, it's confusing and a lot less precise - and can have very peculiar effects, if you have two sibling chicks in a nest hatched on 31 December and 1 January respectively, one would be "1 cy", the other "2 cy" despite being the same plumage :eek!:
lou salomon
the birdonist
cy is much more precise than e.g. the term '1st summer' which immediately invites to confusion with the summer it was hatched in!
Nutcracker
Stop Brexit!
'cy' means 'calendar year' :t:
lou salomon
the birdonist
yes, indeed. it's the term widely used in germany as K1, K2 etc.
Mark Lew1s
My real name is Mark Lewis
I'm a big fan of using cy instead of 1st W etc too. When does one summer plumage change to the following winter one? I think it's more accurate to say what calendar year of it's life a gull is in, without introducing the false precision of summer and winter plumages.
Nutcracker
Stop Brexit!
When it moults. That's easily definable.
Calendar years work reasonably well for most Northern Hemisphere species (crossbills, pigeons*, sparrows excepted), but in the Southern Hemisphere, birds within a cohort, or even a single clutch, hatching in different years becomes a very real likelihood - deciding whether say, a Kelp Gull is first or second cy needs knowledge of the exact date it hatched, which is impossible to determine.
* I've seen a newly fledged, 2 cy Wood Pigeon on 2 January :t:
Especially with the northern and southern hemispheres, ie a northern hemisphere summer is a southern hemisphere winter.
Mark Lew1s
My real name is Mark Lewis
Not sure moult is easily definable - When it moults what? Which tracts of feathers? Moult in herring gulls can take up to 6 months to complete, so do you go from the start or the end of the moult period?
Point taken about the southern hemisphere spp though - I hadn't considered that at all, and it definitely muddies the waters. Still, I think for species when the year of hatching can be determined, the cy system is better.
lou salomon
the birdonist
mostly agree with the above. some species of large gulls moult more or less continously.. but there are strong arguments in favour of the 3rd possible ageing system which is indeed the moult cycle system, used in the united states and among many gullers. it's defined by the start of primary moult.
but as for the cy-system: it just describes the exact age a bird is and not the plumage it is in. plumages change all over the year, so, even 1st or 2nd winter and the adult plumages (which are rel. stable) are relative since a large variation within individual moult timing can make birds of same age look totally different; but the moult cycle it is in together with the calendaric date allow a very precise approachement to its actual age and state of its "perpetual metamorphosis" during immaturity.
as for the southern hemisphere breeders: i find it even more of an advantage not to use terms like 1st winter for e.g. kelp gull because of the inverse seasons there - so with calendar years a southern hemisphere age is described much more precisely, imo.
