Is this a Wahlberg's Eagle? (1 Viewer)

Taken in Kruger National Park on 4th April 04.

It may not be a good enough image to distinguish as it is very similar to the Steppe Eagle, but the gape doesn't seem to extend back far enough

David

Yes! With this one I usually draw an immaginary line from the posterior gape angle vertically through the eyeball. This one seems to take only the craniad one-third of the eyeball. All other possible confusion species in this zone have gapes that take up at least half, if not more, of the eyeball.

I agree with Cuckooroller but haven't a clue what he's talking about as I've only ever seen this species in flight. A particularly memorable one was in Christon Bank Nature Reserve, near Harare, which provoked some spectacular air defence from the local Fork-tailed Drongos.

To me the yellow cere, relatively small bill and steep forehead identify this as a dark phase Wahlberg's Eagle.

david kelly said:

I agree with Cuckooroller but haven't a clue what he's talking about as I've only ever seen this species in flight. A particularly memorable one was in Christon Bank Nature Reserve, near Harare, which provoked some spectacular air defence from the local Fork-tailed Drongos.

To me the yellow cere, relatively small bill and steep forehead identify this as a dark phase Wahlberg's Eagle.

Click to expand...

Hi David,
Sorry if my explanation seemed a little abstruse! Yours are also good indicators. I wish I was more adept at PhotoShop so that I could concoct a diagram to illustrate what I mean. It is good only to separate the Wahlberg's. In words, if you can imagine a profile view of the Wahlberg's head exactly on a horizontal plane - place an immaginary point right where you see the yellow of the gape ending (where the two mandibles are hinging), now imagine a line extending from that point exactly perpendicular to the immaginary horizontal line that you have traced through the head in profile and extending up through the crown. You will see that according to the species of Eagle that is being considered a varying fraction of the transected (by the immaginary vertical line) eyeball will be included in that side of the line occupied also by the mandible. In the Wahlberg the fraction of the eyeball included along with that side with the mandible is approximately one-third. Doing the same thing with other southern African ranging eagles will give you a portion of the eyeball included with the mandible that is at least one-half and usually more of the eyeball. I hope that I haven't confused you more with this rather contorted explanation.

:news:

Does this help Steve

Jane,

That's kind of the idea, but not quite. I usually just eyeball it and I don't run the horizontal plane through the head parallel with the gape line as it has been done here. Too much of the eyeball has been taken it looks like. I'll see if I can find a better photo of the head in my database. I would have have rotated it down a bit, as if I had stuck a pin in the intersection of the two lines and put my finger on the line jutting out from the right and pushed it down.

I was worried about head angle affecting things so took the inner part of the gapeline as a horizontal... will have a crack at Steppe eagle!

Well using the same method the difference is marked!

Here's my pitiful shot at using PhotoShop.

Yes, nipalensis has a very long gape line. If I just eyeball it imagining my method I would say it arrives all of the way back, or almost, to the aboral aspect of the eyeball.