Tuesday, 15 July 2008

Two Ravens

..... or Twa Craws for ony Scots amang us.

Until now I have assumed all four Raven photographs below were of Forest Raven - Corvus tasmanicus. Indeed that is probably still the case. However, I have recently read that the Little Raven - C. mellori also finds it's way to the north coast of Tasmania, albeit rarely. Other than size, which is difficult to estimate from a photograph, most of the features used to differentiate between the two species require having the bird in your hand. The one more visible feature that I'm aware of is the Little Raven is said to have more prominent throat hackles while the Forest Raven's throat hackles are said to be inconspicuous.

The first two photos below are of a Cradle Mountain bird which is surely, on location alone, a Forest Raven. Photos #3 and #4 show a second bird at the Duck River in Smithton on the north-west coast. While in all likelihood they are both Forest Ravens, the throat hackles on the Smithton bird are hardly inconspicuous. I've only been back in Australia for a relatively short time so if any experienced birders out there wish to opine on the matter, I would be grateful. I suspect they are both Forest Ravens but I would like to understand what makes them so.

#1 Forest Raven at Cradle Mountain


#2 The same Forest Raven at Cradle Mountain


#3 Raven at Smithton (prominent throat hackles)


#4 Raven at Smithton

Edit: After
Anonymous's comment below, I thought I show details of the eyes.
#5 Cradle Mountain bird on left & Smithton bird on right


18 comments:

  1. Very difficult! I also identify via hackles. They say the Forest Raven (or Tasmanian Raven) has a white eye-ring around the pupil whereas the Little Raven have white eyes with an inner blue ring. I don't know if the top two photographs show a surprised Raven, but look at the difference at its apparent wide open pupils! Hhahaaa, grasping straws here! You'd see more in your original images. If that doesn't help, start differentiating their calls ;) Hope someone else can help more!

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  2. Thanks Anonymous. I've edited the post to show a more detailed photo of the eyes. Your comments have me even more intrigued now :-)

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  3. HAHA, I've only complicated things! The right eye has a tad blue line on left of iris but the sky could have also been bluer that day! ;)

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  4. LOL - Like I need it to be any more complicated. The thing is, when I photographed the Smithton bird I though it looked a bit odd but as I didn't realise we got any other Ravens here I dismissed any ideas of it being a different species.

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  5. Och mon, the size o' the bill is a guid field mark an a'. The Tassie raven has the most massive o' them a'.

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  6. Duncan - you're a poet of the same ilk as Burns himself :-)

    OK - bill size is interesting. I'll look into that.

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  7. While you're looking into different sized Raven's bills (try not to be pecked) I'm trying to work out what the Scot said about the Twa Craws! *sigh* Will check back tomorrow :)

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  8. Well "Two Ravens" sounded terribly posh compared to a good Scottish, "Twa craws" (Two Crows). When It wrote "Two Ravens" It reminded me of a Scottish song - a kids Song. There are various versions. Twa Craws and Three Craws etc. Here's one version I just found on YouTube:

    Click Here

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  9. Hi Mosura.
    In central NSW (but highlands, not out on the plains) we get the Australian Raven (from which your Forest Raven was split off, I understand) and the Little Raven. I always thought the Aus. Raven had very long throat hackles, (ionger than the Little R.). However, the main point that I understand to check for is behavioural. I have been told that Little Ravens flock in groups of up to 50 birds, especially in the open, in winter. Also, the call is distinctive - short, shallow calls of LR, whereas the Aus Raven (and likely the Forest Raven) have very long-drawn out calls, of deeper tone.
    Quick Google Image Search shows a true Tasmanian Forest Raven without long hackles, so that part is probably right. Not sure if your "little Ravens" are the same as ones we get here. Presumably.
    Little Raven eye close-up from Canberra here
    .
    Cheers
    Denis

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  10. Well I measured the beaks in relation head size based on photos #2 and #4. No matter which way I measure the Smithon bird has a considerably shorter bill. The eyes are different, the hackles are different, the general shape is different (which I remember thinking at the time). This and comments from others via email have convinced me I have my first Little Raven. Just a pity it took me 9 months to notice.

    If anyone disagrees speak please let me know why.

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  11. Denis - I didn't get your comment until after I posted my previous one. Off to read it properly now.

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  12. Australian Ravens have very long hackles. I've seen plenty of those in my time when I lived in N.S.W. (last century) although my most recent encounter with Australian Raven was in 2006. Forest raven hackles are not that obvious. Little raven seems to be in between.

    That's a great photo of the eye you found. My eye photo was cropped and stretched from a photo that was not too great to begin with so I wouldn't expect to see a clear blue ring like that even if one exists. The flocking behaviour is interesting. Problem is, in Tassie they are generally restricted to King Island. Only rarely do they get to the north coast so you wouldn't expect to see a flock. Unfortunately I do not recall hearing this bird. I'll certainly be listening to the ravens from here on :-) My this is a big reply. I better stop raven on.

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  13. Mosura, I don't know whether this helps, but according to Pizzey/Knight 7th Ed. there are two races of C. tasmanicus. Quote:- Two races: s (nominate) race: big, heavy bird with the most massive bill of any Aust. corvid and shortest tail. When calling, throat fills out, but hackles do not form large shaggy 'bag' as in Australian Raven: points tail downwards as it calls (Debus, 1980) Flight pondorous. N. race, boreus: bill less massive; tail longer. In both races, mated pairs hold permanent territories of c. 40 ha; nonbreeding birds form locally nomadic flocks of c. 30-40 (up to 100 in winter in Tas. End quote.

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  14. Thanks JL - It all helps.

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  15. I'm pleased to check back late to hear the singen, see the eyes and read the ravens! Congratulations on noticing your first Little Raven :))

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  16. Mosura,
    I don't know a thing about Aus. ravens! but just a thought, is the blue eyed bird only blue eyed because it's a young bird.

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  17. Wow, Mosura, that two-eyed creature staring out at me has had a bad night.
    And it cannot even focus its eyes!
    Oh, I get it.
    Nice work. Not sure if there would just be different individuals.
    Who knows, for sure?
    Cheers
    Denis

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  18. Thank Anonymous - Glad you enjoyed it.

    Thanks Warren - Wow that's a whole new line of investigation. I long for the days of Jackdaws, Rooks, and Hooded Crows. It was all so much easier. Mind you, some of your warblers are another story.

    Thanks Denis - "Who knows for sure" just about sums it up. Maybe I should revert to calling all Australian Corvids "Crows" like I did as a kid.

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