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Saturday, July 30, 2011

Pacific Baza found at Calderwood (near Albion Park) NOW UPDATED


Image warning:  This post contains several images of a road-killed bird.
My reason is to record the fact of  this species existence in the area.
But if you find such images unpleasant, please skip tonight's post and please come back to my Blog again tomorrow night. 
My friend Kirsten rang me yesterday in a state of high confusion and high excitement, about an unusual bird she had found as a road kill, at Calderwood, near Albion Park.
Her confusion and her excitement turned out to be fully justified.

It turned out to be an immature Pacific Baza (the so-called "Crested Hawk") It is formally known as Aviceda subcristata. Unfortunately this bird was somewhat damaged and had been damaged on the back of the head (so no crest was evident), and it had lost most of its tail feathers.

On its supposed distribution, the easily searchable sources say: "The Pacific Baza is found in tropical and subtropical forest and woodland in northern and eastern Australia, but rarely south of Sydney." (Source: Birds in Backyards). So, at first we ruled out the Pacific Baza as an option (as to what species we were dealing with)..

Just a word of explanation, it is often surprising how hard it can be to recognise an unfamiliar bird species when one finds one "out of context" such as a road kill.We are simply not used to seeing these things up close and personal. Of course, there is another factor, many species of Birds of Prey undergo significant changes in plumage. In this case, I first thought it might have been a juvenile Brown Goshawk, which are famous for having strong markings on the chest. This turned out to be a red herring  for me, in trying to work out what it was. 

Moral for the day: Just because the references say some bird ought not be where you are does not mean it is not that species. Global Warming (and also changed land use) are clearly changing the distribution of certain species.I mention here two species - the Noisy Pitta, which I have reported from Berrima, NSW (way out of its normal range) and the Rainbow Lorikeet, which has undergone an explosion of its range along the east coast of Australia in the last 20 years. 

Please also see the note below about the Birdata mapping tool to which I was referred by Martin.

Back to the bird in the hand.
Pacific Baza - head with caterpillars in beak (its last meal)
I sought assistance in identifying this bird from the Canberra Ornithologists Group email forum. Part of what was puzzling me is the fact that this bird had clearly been eating caterpillars, probably of grass moths. Such a diet would appear unusual for a Goshawk, as seemingly it had been eating from the ground, not catching its prey on the wing. But the same comment might equally well apply to the Baza.

Anyway, one of the COG people suggest that perhaps my "supposed Goshawk" might in fact be a Pacific Baza. With that thought having been raised, I reviewed the evidence.

What about it supposedly being out of range"?
Unlike what was reported on the Birds in Backyards site, it turns out that Pacific Bazas have been recorded from the Illawarra Region. In fact, near by at Tullimbah. OK - so the Pacific Baza theory is no longer out of the question.

I started to look more closely.
Check out the diagonal nostril line - an unusual feature.
I checked out what the nostril of Goshawk looks like. Geoffrey Dabb has a wonderful shot of  a Brown Goshawk (on the COG Bird Image Gallery) which clearly shows that it has a round nostril hole. OK - so that confirms it is definitely not a Brown Goshawk.

What else can I check out? 
The legs are worth looking at.
Feet and legs are grey; under-tail coverts are pale chestnut colour
Lets look more broadly. The underwings have this colour (which I had previously overlooked). Silly me. 
Under-wing colour and black and white marking on wing tips
Here is the image of a Pacific Baza in flight, from Simpson and Day - "Field Guide to the Birds of Australia" (6th edition).It is blindingly obvious to me - now - that what I have is a Pacific Baza. 

Simpson and Day - illustration of Pacific Baza in flight.
Suddenly it all becomes clear. It is the difference between seeing the details and the overall picture.

The throat colour of my bird is not grey - because it is not an adult - it is immature.

Let me put on record the assistance of several members of the COG chat line,and my Blogging colleague, Martin referring to the HANZAB guide, for sorting out some of these finer details.


Since posting that original Blog item on 28 July, I have followed up a suggestion from a COG member, Philip Veerman, to try to get better images of the beak. He has some experience with this species and told me that a Pacific Baza has a distinctive "double tooth" structure on the beak.

That turned out to be absolutely accurate, and a lovely diagnostic point to confirm the ID by (apart from the unusual shaped nostril already mentioned).

Detail of the beak of the Pacific Baza. Note the double "teeth" notches.
Oh, for the record, yes the dead Pacific Baza had 7 Caterpillars in its beak at the time a car hit it.
7 grass-feeding caterpillars found in the beak of the Baza.
Bazas are well known to be insectivorous. My Blogging colleague, and retired CSIRO Entomologist, Dave Rentz tells me Bazas favour Stick insects found in tree canopies, mostly. And further, he notes that, in the tropics, Lizards and Tree Frogs are also popular food items, normally.
However, these caterpillars are almost certainly grass feeding caterpillars, most likely of the Moth family Noctuidae. I am seeking assistance with confirmation of the caterpillar ID.
If I am correct in them being grass-feeding caterpillars, then obviously such grubs are only found from the ground, by searching closely amongst the lush grasses.
It could not have been flying to pick out these caterpillars from within grass leaves. And surely it would not have achieved catching 7 as yet undigested caterpillars, if flying.
The bird was found adjacent to lush dairy farming country in a district known as Calderwood, close to Albion Park.

So if nothing else that tells us something interesting about the feeding habits of the Pacific Baza.

Another note of interest, another Blogging colleague, Martin, who is also a fellow member of the COG Chat Line helped me greatly by resolving the accurate distribution (range) of the Pacific Baza. He referred me to this site: Birdata - Atlas Distribution Maps. Note: It is "birdata" not bird data. Type in Pacific Baza. 

Obviously you can use any recognised name for Australian birds. The search is not even case sensitive, which is good. It also suggests options, eg, to test it, I typed in Starling, and it offered me 6 alternative species to select from.

I strongly recommend you visit that site and then "Bookmark it" or save it to your "Favourites".

I often comment on how I greatly appreciate collaboration in getting IDs of unfamiliar species, be they plants or moths, or in this case, birds. I have mentioned a number of collaborators in this "quest" by name, above. Kirsten, Geoffrey, Martin and Philip. There were other suggestions and comments offered too along the way. Thanks to them all.

Long may the spirit of collaboration reign - sharing of knowledge is a great gift. 


Mr. Smiley said...

You are a good detective, Denis. up here in Kuranda, these birds seem to specialise on stick insects. They search the trees carefully and then pounce. They also fly into the leaves and branches to attempt to stir up any sticks that might be there. On a less pleasant note, they capture White-lipped and Green Treefrogs and devour the poor things as they scream in pain. Not a pleasant sound in the rainforest but you know exactly what is happening when you hear it.

Flabmeister said...


It has been very cold here this morning so it has taken several hours for my brain to start "working". When it finally kicked in I recalled something about bazas on the South Coast being on the COG chatline in this interglacial epoch.

Using the very excellent Archive of that site I found this, which I post here as being of possible interest to a number of your readers.


Denis Wilson said...

Thanks for that, Martin.
It seems sad that those records exist, but the general "system" (especially Birds Australia) does not know about them.
In the Internet age we ought be able to do better, surely?
At least my record will be available via Google.

Denis Wilson said...

Thanks Dave.
Interesting you mentioned Stick Insects (hardly surprising, though).
I made a comment when a Baza was first suggested by the Canberra Ornithologists, that it ought not have grass-eating Caterpillars in its beak, but Katydids or Stick Insects.
It has lost all but two tail feathers. Makes me wonder if it had been damaged already, (little other sign of moult), if it was walking around in a dairy farm picking up Caterpillars from grasses.
I didn't know Tree Frogs could scream in pain. Sounds nasty.
These birds are famous for their habit of crashing though the canopy to disturb things up there, just as you describe.
I have only ever seen one before, near Coffs Harbour, NSW north coast.

Anonymous said...

I feel totally justified in my odd habit of inspecting roadkill now I have found something truly interesting lol

Denis Wilson said...

Rightly so, Kirsten.
You should feel proud of this one.
Stopping for road kills is a disease, though.
You'll want to stop in the middle of a freeway, one day.
Its a sign of maturity, (or something).
I will send you (privately) several more images which are now 100% diagnostic.

Mr. Smiley said...

My guess is that the caterpillars came from the canopy not the grass. Noctuids and geometrids are found there and a skilled Baza would be able to work out which trees are worth a look.

Some people now prefer to call the poor bird a Crested Hawk with the Baza found elsewhere.

Denis Wilson said...

Thanks Dave.
But you are trying to confuse me now.
Not only are they maybe not grass moths after all (that was only ever a guess on my part);
but a Baza ain't even a Baza any more.
I am referring the caterpillars to Don Herbison-Evans for advice, as you suggested him as a good reference point (in another context) two weeks ago. I shall await his advice.

Flabmeister said...


I would be interested to know who is now calling the Pacific Baza a Crested Hawk. The latter is one of the old vernacular names of the Baza but all the 'authorities' listed in now say Pacific Baza is the 'proper English name.

However if you want to be really confused - or perhaps return from where you started - I see from HANZAB that "Baza is a modern Latinization (sic) of baz a Hindi word for 'Goshawk'"!


Denis Wilson said...

Oh, stop it Martin.
Confusion reigns already, OK?
Leave the Hindi texts out of it, Pls.

Joy Window said...

I'm in northern NSW and several times I've heard a green tree frog screaming as a snake devours it - it's a very disturbing sound, especially the first time you hear it and don't know what it is, and it can go on for a long time. Since ithe frog's been in my roof, I haven't been able to rescue it, but wouldn't anyway - the snake needs to eat, too.

We've had a baza regulary fly across the paddock from the rainforest remnant to the trees near the house, crash violently into them, and stay there feeding. My theory was that the bird was disturbing the insects so it could grab them more easily, but who knows? They are beautiful to see alive, but the details are, alas, easier to inspect if you can find a dead one. I'm on the lookout for a pheasant coucal at the moment - things are warming up and they are sooo sloow getting across the road that, unfortunately, I'm bound to be able to find one that has collected a car and get a good look at it.

Denis Wilson said...

Thanks Joy
Glad to see you also post the occasional informative images of birds, even if dead. Loved your Gannet, for example. Perfectly stream-lined head and beak, for diving into water.
I remember beach combing in Victoria as a kid, and always finding Prions and Shearwaters. Fascinating.
We can learn so much about these creatures, provided we are prepared to examine them carefully, and respectfully.
I will add your blog to my list of "Aussie Nature Bloggers". Lots of good people out there, doing good work, and good reporting.
They need to be encouraged, by spreading the word.