I thought the accompanying image of a pair of Green Rosellas may be of interest. I have photographed numerous Green Rosellas over Summer, either bathing or gorging on the fruit of the Native Cherry. Most of the flocks I've seen have been made up solely of the green plumaged, immature birds, which suggests that this breeding season was good, at least locally.This image, by chance, shows both male (upper) and female adult birds in juxtaposition, and enables comparisons of plumage etc.. I was quite struck by the differences, both in 'bulk' and in bill size. I guess we don't often get the chance to see them like this, and usually just make a mental note, 'Green Rosellas', as they noisily disappear from view!
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I'm always amazed at how yellow our "green" rosella is! I guess when I do finally get to see a Yellow Rosella, it will be more noticeably Yellow than our Green. Not sure when I'll next get a chance to look for a Yellow Rosella, but I'm heading to Perth in May, so I hope to get to see a Western. That will only leave the Yellow, then, for a full complement.
They seem to vary a bit too, sometimes they are much darker than the very yellow ones. Michael Sharland says this is more in wet and mountainous areas.
In the South East at least, a dull bird would certainly be an immature bird. Sharland is somewhat tentative in what he says in relation to colour, unusual for such an excellent field observer. It would be interesting to find adults in wet mountanous country, to compare. I can't say that I've been aware of any difference--certainly those at Strathgordon look much the same as those here.Is it , perhaps, that in the wetter areas, we tend to see flocks of mainly imm. birds, and that the adults remain in the general area of their breeding territory?
I should have made the observation, that the images were shot in the early morning sun, helping to highlight the colours.
My own tentative observations have been that there is a fair bit of light/dark or 'yellow/green' variation across most areas. Maybe reflecting the adult/immature mix. Pizzey suggests the female is generally duller and greener thatn the male, which your shots here, Alan, seem to confirm. There may be variations in colour in different regions or localities in the state, but a bit beyond my skill to quantify. Interestingly, Ron Nagorcka and Sarah Lloyd, at a Birds-Tas meeting last year reported finding dialectical differences in Green Rosella calles i different parts of the state. Would be interesting to see if these corresponded to any quantifiable colour variations - maybe a Phd in it for someone!!
I do agree that there are a range of plumages in Rosellas.I think that you have to bear in mind that it isn't until the 3rd year that the full adult plumage is reached. The majority of birds about at the moment are not adult birds.I've certainly watched and photographed a good few Rosellas in the last several months, and think? I can age birds according to plumage, largely by the extent of the "yellow" in the breast plumage. At the moment, locally at least, the adult birds are not associating with the flocks, but some of the birds in flocks have a degree of "yellow".
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