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Unread postPosted: Thu Jul 12, 2007 8:58 pm 
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Junior Virtual Ranger
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Does anyone know if these are White-backed vultures or Cape vultures. I thought that these were white-backed vultures because of the dark eyes. Arks and Ukbadger however think these are Cape vultures. I saw these near Letaba. Who can help?

Image Image

ImageImage

Image

Thanks in advance.


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Unread postPosted: Fri Jul 13, 2007 7:39 am 
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The dark eye/yellow eye theory has always been my way of separating the two. So I think you are spot on with your call, Anja

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Last edited by Johan van Rensburg on Fri Jul 13, 2007 7:48 am, edited 1 time in total.

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Unread postPosted: Fri Jul 13, 2007 4:31 pm 
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There was a lengthy discussion recently — I think in KDU's trip report? — that in pix you can't reliably see the eye colour and that the bare patches on the chest are diagnositic for Cape vulture. I think that there are both Cape and whitebacked vultures (as well as hooded :wink:) in some of Anja's pix. I'm hoping that francois, snoobab, deestes, BB, TG and others far more knowledgable than I will also weigh in here to clarify?


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Unread postPosted: Fri Jul 13, 2007 4:52 pm 
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Sorry, not me on this one, I need to see the wings extended from underneath.

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Unread postPosted: Fri Jul 13, 2007 5:44 pm 
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Here are some photo's of vultures with the wings widespread, maybe that will make the id easier. But if it was a mixture of cape and white-backed vultures than I think it will be difficult.

ImageImage
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Unread postPosted: Fri Jul 13, 2007 5:53 pm 
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Great pics, Anja, but I'm still :?
Hope someone can give us a positive ID, these vultures really confuse me :cry:


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Unread postPosted: Fri Jul 13, 2007 7:54 pm 
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arks wrote:
in pix you can't reliably see the eye colour and that the bare patches on the chest are diagnositic for Cape vulture


It is not the bare patches per sè that are diagnostic, but rather the colour of those bare patches that can assist in the ID as both species have these bare patches. I have never subscribed to using the bare patches' colour as an ID-feature as the colour can vary tremendously depending on a great variety of factors. Here are my take on the best features to make an ID.

Number 1 (best feature by FAR) - dark-eyed birds are WB while golden-eyed ones are Cape.

Number 2 - Where this can be seen, a white rump = WB; uniform-coloured rump and back (pale brown) = Cape

Number 3 - Uniformly brown flight feathers = WB; spotted upper-wing coverts (black, ad.; white, juv) = Cape.

All other differences often stated (differences in size, downiness and length of neck, length, thickness and colour of neck, colours of the crop patch or the "robot" patches) are too subjective and prone to variation that I do not subscribe to using it.

Not one of the pix shows the rump/lower back of a bird exposed, so only Points 1 & 3 can be used to ID the birds. All of the birds show a dark eye and, if you feel compelled to look beyond that clincher, all of them display feather patterns congruent with juvenile or adult WB vultures.

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Unread postPosted: Fri Jul 13, 2007 9:56 pm 
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Johan, thanks for your explanation.
I looked in some bird guides and I think it's still very hard to see the difference. For now the eyes are the easiest way for me to identify them. When I'll visit Kruger again, I will have a better look at them. Maybe I'll learn then.


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Unread postPosted: Fri Jul 13, 2007 10:26 pm 
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It is a massive pleasure, Anja. I couldn't agree with you more about it being difficult to ID these birds. However, when you have the two species together, that is when you really learn to spot the differences. I hold thumbs that this happens to you some day. Generally speaking Cape vultures are scarce in the KNP so that such opportunities are few.

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Unread postPosted: Mon Jul 16, 2007 8:28 am 
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Hi Anja.
There is a mix of Cape/WB vultures in your pics (as well as others). In your first posting the top right looks to be a WB vulture and bottom pic looks to be a Cape. As JvR says the eye colour does tell them appart but as I've said before IMO unless you get the perfecr angel eye colour can be misleading. I prefer the bare patches, if it is blue then it is a Cape no question. Some WB do have patches but they are light and not always easy to see. Size is also a factor but in the pics it is a bit tricky as no two birds are standing next to each other for a perfect comparison. When the two birds are together also look at the colouring as in most cases WB are darker than Cape. Your bottom pic of the Cape has a lighter colour than the top right.


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Unread postPosted: Mon Jul 16, 2007 7:28 pm 
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Thanks for your response, Snoobab.
I'll keep it on a mixture of vultures. When there will be a next time in Kruger, I'll will have a better look at them. I think it's easier to identify them in real, than from a picture.


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 Post subject: Vultures
Unread postPosted: Fri Jul 20, 2007 9:57 am 
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I just want to get back to Anja's vulture pics.

IMHO they are all Afr White-backed Vultures.

As we all know, distinguising AWV from Cape Griffon is difficult. Size is a good feature but only to the experienced
observer, or when a direct comparison can be made.

Below follow some features which I use to help me identify the standing bird:

The adult CG's yellow eye and the adult AWV's white rump are about the only clinchers - that is if you manage to see them. Therefore a combination of features are often needed for identification, and correctly aging a bird is important in this regard. Remember that the white rump of AWV only starts to appear at around four years of age.

The juvenile and immature CG vary in their colouration but they have a chracteristic pink neck which separates them from the smaller AWV. They lack the adult's yellow eye. The tips of the upper greater wing covert feathers are pale, while the rest of the feather is dark, resulting in a pale line across the closed wing in the standing bird.

The adult CG loses its streaked immature plumage, whereas the AWV retains it, often only on the breast and belly, although it is fainter than in younger birds. The feathers at the base of the neck (ruff) become short and wiry in the adult CG, while they remain lanceolate in shape in the adult AWV. The colour of the bare skin patches at the base of the neck is not a good diagnostic feature, and can be blue in both CG and AWV. However, it is usually more intensely blue in the CG. The skin of the neck and head of the adult CG has a blueish colour, although it can be flushed with pink in an excited bird. AWV shows black neck and head skin.

The statement in the SASOL Birds of SA field guide indicating that the bare patches of blue skin at the base of the neck in the adult CG are diagnostic, is incorrect.

Another important feature to look for is the colouration of the upper greater wing coverts: adult CG shows dark central blobs, while these feathers are mostly dark in the adult AWV.

I trust this will help.

TG


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Unread postPosted: Fri Jul 20, 2007 10:28 am 
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Quote:
IMHO they are all Afr White-backed Vultures.


Oops...there are also two Hooded Vultures in the pics.

TG


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Unread postPosted: Fri Jul 20, 2007 10:32 am 
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Thanks for the explanation TG. :thumbs_up:

Think I'll have to print it, read it 3 more times, then go to the photos and read it 2 times while looking at the photos :lol:

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Unread postPosted: Fri Jul 20, 2007 7:20 pm 
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TG wrote:
I just want to get back to Anja's vulture pics.

IMHO they are all Afr White-backed Vultures.

As we all know, distinguishing AWV from Cape Griffon is difficult. Size is a good feature but only to the experienced observer, or when a direct comparison can be made.

Below follow some features which I use to help me identify the standing bird:

The adult CG's yellow eye and the adult AWV's white rump are about the only clinchers - that is if you manage to see them...

...The colour of the bare skin patches at the base of the neck is not a good diagnostic feature, and can be blue in both CG and AWV.



Thanks for that TG. This is just about verbatim my feeling regarding the ID difficulties these two birds present.

Furthermore TG wrote:
The statement in the SASOL Birds of SA field guide indicating that the bare patches of blue skin at the base of the neck in the adult CG are diagnostic, is incorrect.


I have wondered about that bit as none of the other fieldguides or Roberts VII says different - they just omit to commit! (Refuting mistakes in other fieldguides, on the other hand, is not their function :roll: )

To add another factor that further confuses the issue - in a feature article Refining our vulture culture published April 2004 in Science in Africa, the Vulture Man, dr Gerhard Verdoorn wrote:
Quote:
Three other griffon vultures are found in Africa - the Eurasian Griffon Gyps fulvus, Rüppell's Griffon Gyps rueppellii, and the African White-backed Griffon Gyps africanus. These griffon vultures are very closely related to each other and interbreeding between Rüppell's Griffon and the Cape Griffon has been recorded in South Africa. There is strong phylogenetic evidence that Cape Griffons have interbred with African White-backed Griffons in Namibia.


This gives credence to the suggestion that ID of these birds should be kept simple and along the (fool)proven :lol: methodologies. Once one gets too sophisticated too soon you are bound to make mistakes.

Unless you are a subject expert, the only ID-features you should consider are as per an earlier post:

Number 1 (best feature by FAR) - dark-eyed birds are WB while golden-eyed ones are Cape.

Number 2 - Where this can be seen, a white rump = WB; uniform-coloured rump and back (pale brown) = Cape

I hesitate with Number 3 - Uniformly brown flight feathers = WB; spotted upper-wing coverts (black, ad.; white, juv) = Cape. My hesitation is due to this being a much simplified "rule" and if the (even experienced) observer is not careful, it too can lead to confusion.

As TG wrote:
correctly aging a bird is important in this regard.


When it comes to using the plumage coloration of these birds as an ID-feature: if you do not understand or know the stages they go through as they age, rather leave it alone.

All other differences often stated (differences in size, downiness and length of neck, length, thickness and colour of neck, colours of the crop patch or the "robot" patches) are too subjective and prone to variation that I do not subscribe to using it.

This is the guideline as I employ it in my own birding of vultures. I am chuffed to find other more experienced birders enjoying much higher regard suggesting the same rules for safe and sure identification of these birds. :dance:

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