Currawong tails

Okay, I'm puzzled. I am hardly and expert when it comes to bird identification, but I thought I had my currawongs sorted - until yesterday. I had headed out for a gentle ride around the river via Fyansford and Breakwater, snapping some photos as I went.
As I headed down from Queen's Park towards Princes Bridge, I spotted a feathered tail hanging from a branch arching over the path. At first glance the underside was black and white striped. Upon closer inspection I discovered it was black tail feathers of varying lengths, each with a white tip giving the banded appearance. What was interesting about this was that the tail was attached to a Pied Currawong.
Now, to this point in time all the Pied Currawongs I'd seen had the typical white undertail and then a thin band of white at the tip - like this guy photographed in my backyard in April, 2010.

Pied Currawong April, 2010

This one looked similar to the bird in my tree at home, with the exception of the tail feathers. Curious, I went back to the same part of the river again today to see if I could find him/her again. I didn't have to look too hard before I was able to locate not one, but a pair of currawongs in the same area as yesterday. Both had the same tail markings I had seen on yesterday's bird.

Pied Currawong 1

I spent quite some time taking shots and they allowed me to approach to within a few metres, watching closely but not particularly concerned by my interest. Initially they busied themselves shredding the bark off the branch they were perched on before scooping out any creepy crawlies to be found inside. The only concern they showed was when they moved to a tree near a magpie who then attempted unsuccessfully to send them on their way. The magpie soon retreated and peace was restored.

Pied Currawong 2

So, armed with what I hoped was ample evidence to prove my point, I finished taking my shots and left them to it.
Now, several hours and many webpages later, I am still none-the-wiser as to what I am seeing here. My question for those who read my blog and know more about birds than I do (and  suspect there are a few) is this: are these juvenile birds whose tail feathers have yet to grow out properly or am I looking at two of the six different subspecies of Pied Currawong?
Certainly one of the two birds I saw today had paler grey feathers on its chest and could have been a young one. Neither looked anything like the rather large Grey Currawong I saw a couple of months back near Baum's Weir which was the subject of an earlier post nor were there any calls from these birds - although I did hear others calling further upstream on the opposite side of the river.

Finally, while I'm discussing currawongs, I noticed that the topic of the appropriate collective noun for these guys was a recent point of discussion on Denis Wilson's "The Nature of Robertson" blog here. When I first read this post, I was sure I had the answer to that one, but after looking back over my own currawong posts, it seems I do not, so I too would be interested to know if there is such a noun.

"Clink! Clunk!"

My previous blog about Currawongs has proven to be one of my more popular posts, so when I managed to snap a couple of photos of a Grey Currawong as I was walking around Mt Brandon Peninsula during the week, I thought it was time to revisit the topic.

Grey Currawong

As I said previously, Pied Currawongs can be seen regularly at many points along the Barwon and in surrounding areas - including my backyard. Grey Currawongs are a different matter.
Until this week, I had never seen one. This may not be such a surprise as Grey Currawongs are not as numerous as their pied cousins and their numbers have suffered as a result of habitat loss with the arrival of European settlement.
As the name suggests, they are a grey bird with the piercing yellow eye typical of all currawongs and their shape and size is also similar. Their colouring however is somewhat different. They do have the white-tipped tail seen in Pied Currawongs, however their plumage is usually grey or grey-brown rather than black. Just to complicate the issue, there are six recognised subspecies of the Grey Currawong, each with variations in colour.

Grey Currawong

As far as I can tell, this particular bird was probably of the versicolor type. This is the "nominate" or original type to be identified and is found in the east of Victoria and New South Wales. It is grey to brown in colour and has white on its wingtips. Other subspecies are the Brown Currawong (intermedia), found in South Australia. It is a darker grey-brown colour. The Clinking Currawong (arguta) is large and sooty black coloured and found only in Tasmania whilst the halmaturina subspecies is dark coloured and lighter-weight than other subspecies and found only on Kangaroo Island. The Black-winged Currawong (melanoptera) is found in the Mallee and into South Australia and the plumbea subspecies (also called squeaker) is found in the west of the country.
Unlike the other subspecies, the Squeaker and Black Currawongs have no white on their wings.
The names Squeaker and Clinking Currawong come from the call of the Grey Currawong which is said to sound like a high-pitched "clink" or ringing sound. From memory, the couple of calls I heard were  coarser and more like a croak. Certainly nothing like the call of the Pied Currawong.
The experts also inform me that these guys spend more time on the ground forraging for food than their pied counterparts, which fits  with the behaviour I was seeing in this bird. They are omnivores who eat all manner of creepy crawlies as well as fruit, seeds, eggs and carrion.
They also nest high in trees, making it hard to study their nesting habits. Co-incidentally or not, high in a eucalypt not far from where I observed this bird, was a nest of sticks. I don't know who it belongs to, but perhaps it bears further investigation.