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 Post subject: Thrush, Karoo
Unread postPosted: Tue Nov 20, 2007 12:49 pm 
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Olive Thrush
Olyflyster

Turdas olivaceus

Image

Food: Insects, molluscs, spiders, small lizards, fish, nestling birds, fruit and seeds.

Habitat: Evergreen forest in E but riverine bush, exotic plantaions, gardens, parks and orchards in other areas.

Habits: In pairs or single. Forages on ground, running, stopping and pecking at ground or leaf litter. When disturbed flies up wit a tseep call ussually landing in a tree. Starts singing before dawn.

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Last edited by Candy's Style on Wed Nov 21, 2007 11:19 am, edited 1 time in total.

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 Post subject: Re: Olive Thrush
Unread postPosted: Tue Nov 20, 2007 2:29 pm 
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Hi Candy's Style,

Where was this picture taken? It looks a lot like Karoo Thrush to me (grey flanks, yellow eye-ring, all yellow beak etc.)

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 Post subject:
Unread postPosted: Tue Nov 20, 2007 4:17 pm 
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Now you've gone and confused me Deefstes :lol:
It was taken in Johannesburg. In the Kempton park area so I think the Karoo Thrush just might miss this area.
Here is a picture of the front:
Image

If necessary I could take more pictures as it visits daily. Have a look here as well:
http://www.birdinfo.co.za/landbirds/21_ ... h%20id.htm

Hmmm.. Nope I think you are right about this... My dads going to be shocked when he hears about this one :D

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 Post subject:
Unread postPosted: Tue Nov 20, 2007 4:30 pm 
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You should be happy CS, another tick. I was when it was pointed out to me in Addo.

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 Post subject:
Unread postPosted: Tue Nov 20, 2007 4:41 pm 
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You right BB :D
Except I think I better take the Olive Thrush off now since it's been a Karoo all along :lol:

Is the Karoo a new species then because it isn't in my books? Unless it is a Kurrichane Thrush but the illustration dosen't look like it... In the link I gave early it said there has been no definitive publication yet. So have the Olive and Karoo evolved from each other?

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 Post subject:
Unread postPosted: Tue Nov 20, 2007 4:48 pm 
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Haha, whether they've evolved from each other can be debated very heatedly but yes, they are two very closely related species and have been considered up until recently to be a single species. This is why your book shows only Olive Thrush. But about 4 or 5 years ago they were split into the inland (roughly speaking) Karoo Thrush (Turdus smithi)and the coastal (roughly speaking) Olive Thrush (Turdus olivaceus).

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Unread postPosted: Tue Nov 20, 2007 5:06 pm 
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Now I cannot wait to get to Addo again to see if I can find the Karoo thrush- thank you, I didn't know there were the two - I have seen what I thought was the olive thrush at Addo, but now I will never know if it really was, so will have to find it again! Will definately look closer now, and not just assume "it's another Olive Thrush"!


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 Post subject:
Unread postPosted: Tue Nov 20, 2007 5:22 pm 
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I don't know the Eastern Cape all that well but I think that Addo will probably also produce only Olive Thrush.

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 Post subject:
Unread postPosted: Tue Nov 20, 2007 7:06 pm 
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deefstes wrote:
I don't know the Eastern Cape all that well but I think that Addo will probably also produce only Olive Thrush.
A chap called Naas ? was in the unit next to some of my party at Addo recently. He is a retired SANP staffer, and told the lady about the Karoo thrush. Armed with this info, we looked for, and found it to be true. When you get to a certain standard of birding, you 'cheat' yourself from new species by familiarity, by 'thinking' it is an olive thrush, but now I am a bit more circumspect. Thanks Naas!.

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 Post subject:
Unread postPosted: Tue Dec 18, 2007 11:28 am 
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Relatively similar in appearance, the olive thrush differs by having a white throat, spotted/streaked with grey; a brown eyering, orange flanks and belly, upper mandible partially brown and a white vent with dark grey spots. Both Newmans and Sasol field guides have the olive thrush's vent colour incorrectly specified as white only. Roberts VII (not a field guide by any stretch) has it correct though as per posted picture.

The Karoo thrush has no easily discernable markings on its throat or vent, both being a drab grey, while the eyering is orange in colour and the bill lacks the brown “nostril spot” and is completely orange/yellow.

Image
Olive Thrush

Image
Karoo Thrush

In these pix the leg colour of the Olive thrush also appears to be markedly different (pink/brown) as opposed to the yellow/orange legs of the Karoo thrush. This feature is variable in both species though.

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 Post subject:
Unread postPosted: Tue Dec 18, 2007 11:55 am 
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Hi JvR, I'm a little confused by your pics as both look like Karoo Thrush to me. Where was your Olive Thrush pic taken?

To me there are two features that are particularly useful in telling these birds apart:
1. Colour of the flanks
2. Colour of the maxillary base (the base of the upper mandible of the bill)
There are more features (which this site discusses very nicely) but these two I find most useful.

1. Colour of the flanks: While the amount of orange on the underparts is quite variable in both of these two species (even though generally more prominent in Olive Thrush), it is restricted to the centre of the belly in Karoo Thrush. This means that the Karoo Thrush always have grey flanks, regardless of the amount of orange visible on the underparts. Olive Thrush on the other hand always shows orange flanks.

2. Colour of maxillary base: The Olive Thrush always shows a black blotch on the base of the upper mandible (the area surrounding the nostrils) while Karoo Thrush have an all yellow bill. The amount of black on the upper mandible of Olive Thrush can vary and will sometimes stretch as far forward as the tip of the bill (giving the bill an all black upper edge) but at the very least it will encompass the nostrils.

Your bird seems to fall short on both of these features. I could be wrong in that they are not absolutely diagnostic but such have been my experience. Other than that I woud also have expected Olive Thrush to show more of a white thoat but this is a feature which I think is mostly objective and not diagostic.

One thing I will say is that your bird lacks the yellow eye-ring of Karoo Thrush. I'm not quite sure what to make of this but I'm wondering if, together with the apparent lack of colour to the legs, this doesn't perhaps point to a younger bird.

Then again, you may answer that this bird was photographed in Durban, in which case I'll just shut up and crawl under a rock. :D

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 Post subject:
Unread postPosted: Tue Dec 18, 2007 1:15 pm 
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deefstes wrote:
Then again, you may answer that this bird was photographed in Durban, in which case I'll just shut up and crawl under a rock. :D


OK! The photograph was taken in Durban :twisted: :lol:

Seriously now, GGNP produced these pix. I wish I had better shots of that specific bird, but the shots were taken against the lighting, resulting in a highlight right in the upper mandible where we want to see a dark nostril spot. However, I am sure about the nostril and throat patch and the vent feature as these can clearly be seen in some of the other pix. Overall none where as good as the picture in this thread though (sharpness/composition) and therefor it got used for my example.

Have a look at this shot (same place, different bird) and you will see the orange on the flanks extend all the way up to and underneath the wings. Again the angle and lighting is wrong for the upper mandible, but enough detail is already evident... (vent, flanks, eyering, distribution :lol: )

BTW, I love the clear and precise way you have of explaining issues about birds. :clap:

I don't have any better pix to explain the issues, but the deeper the debate goes, the better this thread becomes as an informative piece! Thank you muchly for the link. :thumbs_up: Except for showing the differences in the vent (? :big_eyes: ?) forumites now have a complete reference work at their finger tips.

(The vent thing will become an obsession with me now...)

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 Post subject:
Unread postPosted: Tue Dec 18, 2007 2:16 pm 
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Johan van Rensburg wrote:
Seriously now, GGNP produced these pix.


Boy oh boy! Didn't you just have to go and pick a spot where these birds are particularly confusing :lol: Golden Gate is pretty much on the distribution boundary of the two species (although still inside Karoo Thrush territory) but the hillarious thing is that it falls within a very limited region where, wait for it.... hybridisation occurs! Which means your bird culd even be a hybrid between Olive Thrush and Karoo Thrush!!!!

Actually, to be fair, I'm not 100% sure of whether it is a hybridisation zone or whether the geographic variance is just such that birds from that area show features of both species.

I had a look at your picture and I'm afraid but I'm still not convinced. I don't really think the pic shows the flanks well enough but I don't think the vent is a diagnostic feature and certainly not in that part of the world. I'm sorry to be a fly in the ointment but I still think your bird is a Karoo Thrush. Another thing to bear in mind is that Olive and Karoo Thrush have different habitat preferences with Olive favouring a more moist and dense vegetation as opposed to open growth that Karoo favours. I should think that Golden Gate has typical Karoo Thrush habitat and rather atypical Olive Thrush habitat.

In January of this year there was a bit of discussion on SABN on this very issue. There were two very useful responses from Etienne Marais and Mostert Kriek (two very accomplished birders) which you can find here and here.


Johan van Rensburg wrote:
I don't have any better pix to explain the issues, but the deeper the debate goes, the better this thread becomes as an informative piece! Thank you muchly for the link. :thumbs_up: Except for showing the differences in the vent (? :big_eyes: ?) forumites now have a complete reference work at their finger tips.

Indeed, I think this type of debate facilitates some more in depth study of the birds which, eventually just leads to a more intimate knowledge - something we can all aspire to.

Johan van Rensburg wrote:
The vent thing will become an obsession with me now...

I don't think it should. I really believe that the bill and the flanks are far more important features than the vent. Besides, they're far more easy to see anyway as both Olive and Karoo Thrush are generally ground birds that don't flaunt their foefenjol too pertinently :wink:

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 Post subject: Re: Identification Help - General Birds
Unread postPosted: Sun Sep 07, 2008 5:07 pm 
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Please help me ID this bird. Seen in Potchefstroom
Image
Image

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 Post subject: Re: Identification Help - General Birds
Unread postPosted: Sun Sep 07, 2008 8:07 pm 
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Hi Yolande - your Potch bird is a Karoo Thrush.

Cheers

Niall.


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