Thursday, October 24, 2013

Bird Week Day 6 - The Problem with Corvids

I feel that there has been some renewed interest in correct corvid identification in Australia. Sean Dooley's well-written article The Trouble with Ravens in a March 2012 edition of Birdlife Australia's magazine recounted the evolution of his own assumptions with differentiating (in his case) between Australian and Little ravens (as a school kid I might add!).

Sean describes how some of the features that the field guides have us rely on to "assist" with corvid identification are really not that clear cut and that some regions do not have the mix of corvids that we thought might have existed.

As we become more experienced bird watchers there does develop a greater sense of being able to recognise "something different" from what we are used to seeing. It appears that with corvids this skill is not so useful. For me, a Melbournite, I have had to adjust to not immediately thinking "Australian raven!" when a "crow" looks a bit larger than usual or appears to have prominent throat hackle feathers or has a particularly long trailing call. I am now more aware that in the parts of Victoria I most frequent the prominent raven is said to be Little raven Corvus mellori.

Just look at those hackle feathers! Silverleaves Beach, Phillip Island, 2 January 2011
As a result I find that I am now generally leaving corvids off my lists altogether unless the bird has all the identifying features of the dominant corvid species of the region. If there is any doubt the record will be "unidentified corvid".

Correctly some moderators of Eremaea Birds are going through older lists and asking birders to review their corvid identification. This has prompted me to review my old Phillip Island lists that feature Australian ravens. This is because Little raven are considered common there and Australian raven unlikely to occur.

Now I don't usually photograph corvids. As Sean Dooley mentions "ravens and crows often feel like background noise". But there was one day in early January 2011 when I was drawn to observe a trio of ravens while walking along the beach east of Silverleaves on the northern most part of Phillip Island (see location geotag, I have been quite particular). The birds were perched on a prominent bare branch of a dying Coastal banksia. I can't recall the call but there was something different about these birds and I found myself gathering a case for them to be Australian raven. I remember thinking they "seemed" big and the throat shackles were bearding very nicely.

Little, Australian or Forest raven?
I see that field guides also record Forest raven Corvus tasmanicus as sometimes being present in southern Victoria. I have never identified these birds so cannot really assess whether the bill is "massive" enough, the hackles are typical or whether the tail is pointing downwards enough.

Any suggestions?

Is that tail pointing downwards in a Forest raven fashion?
I trust my birding instincts enough to believe that I don't really think I was watching Little ravens on this day.

However I suspect I will be adjusting my list to un-tick Australian raven and record ....

Unidentified corvid
Bird on!

3 comments:

  1. sounds like a good idea Pete un-ID'd corvid ------- must spread the word :)! I've also picked up on the word "craven" as a helping hand.

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  2. I remember when I first started putting lists up on Eremaea, I was pulled up on saying I'd seen an Aussie Raven at WTP and I was mortified! (Though they were quite right.)

    I don't think I can help you with those photos Pete - my strategy is to always go by call. Little and Australian Ravens have quite distinctly different calls, with the Littles sounding like a 'normal' raven to us Melbournites and the Australian with a slightly higher pitched call on average with a longer trailing 'aaaaaaaaaaaaaaaaaaaaagghhhhh' than the Little.

    Buggered if I'd know a Forest Raven if it hit me in the face but I'm going to Tassie in a couple of weeks, and the Forest Raven is the only corvid on the whole island, so that should be an easy one!

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  3. Interesting post and I'd love to read that original Sean Dooley article! I've felt this way about Crows and Ravens before - I'd say it's a safe bet that almost all corvids in Brisbane are Torresian Crows, but every now and then one will look a little strange.

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