I have recently been sent (and been given permission to use) these three pics of a vulture, taken in Extremadura. As can be seen they have many characters associated with Ruppell's Griffon, however there seems to be some debate : -
' A Griffon expert declared it as a Eurasian, and so the photographer has decided to 'back down' and not send it in, but I believe it's a strange-looking Rüppell's (or hybrid?!).'
The discussions have generally gone down the right lines, starting (importantly) with ageing the bird - it's seems to be an adult, based on neck ruff colour and feather form, bill and eye colour and (in my opinon) general appearance (with lots of very similar feathers, even if of slightly differing ages and consequently wear). The flat-topped head seems wrong for Eur. Griffon (but which from pics looks ideal for Rüppell's). The overall appearance of the bird is spot-on for a Rüppell's, with pale wings contrasting with otherwise rather dark upperparts (something I've only noticed by looking at pics, and especially due to a poor shot of a young bird caught, ringed and released in S Spain), but the rather strange overall tawny colour is very off-putting and has clearly lead to the idea it my be a hybrid. The bill also shows a dark mark towards the distal part of the cutting edge (of the upper mandible at least).
Each body feather, has a (wide) terminal band, and are not streaked like a Eur. Griffon would be (without going into distinctions between the different feather tracts, some of which (gr coverts from memory) can occasionally show a pattern not disimilar to this in some griffons), and with wear, these would become distinct cresents or spots, as in Rüppell's. But the colour and length of these terminal bands appears at odds with a typical Rüppell's; the extra down on the neck also appears at odds with a typical Rüppell's too (where the skin colour -which changes with ?temperature/mood- often shows through), and perhaps the overall colour is wrong not being the deep and dark sepia of Ruppell's.
Below is a link to Ruppell's images as a starting point, but I would be grateful for other comments.
[On the last image below the vulture discussed is the front-on bird on the far left]