Great grey shrike , Benghazi (top) and desert grey shrike, near Tripoli (bottom)
I have commented before that the shrike found in the city of Benghazi doesn't look anything like the desert grey shrike elegans which most maps suggest should be here. On the left above is a typical dark shrike found in the city and the surrounding north east Libyan countryside. This one was photographed at Buduzeera park last week. In every way it is darker than the known desert grey shike. It has less white on the wings, its back is a slate grey (with a hint of brown!) and it has no white over the top of the eye. It's underside is not white, it is grey. But it doesn't take a detailed description to see the difference. In the field it is obvious.
It looks more like great grey shrike aucheri. There is now some real debate whether aucheri extends from Sinai (where it is known for sure) through northern Egypt to Libya. From my angle it looks certain that the old maps which suggest only elegans in north east Libya are wrong unless the bird has a remarkable geographical variation in colour!
probable elegans north east of Benghazi
Outside the city, the apparent distribution is about 50% elegans, 35% darker bird (aucheri?) and 15% which look in between. But even the apparent elegans found here is darker than in Tripolitania (compare the one above with the one at the top of this blog).
Even in Tripolitania (north west Libya) elegans does not have the place to itself. There are about 20% algeriensis (not pictured). And in mid winter (and only in winter) we can see a few birds with pink bellies. These look like Iberian grey shrike. Again the maps don't hint that it strays that far from its summer residence. However I have seen Tunisan trip reports which also record it.
+Tripoli+East+Feb10+(640x430)+peb.jpg)
probable Iberian grey shrike, Tripolitania in winter
I know that the experts on the great grey shrike complex are keen to find the truth. It looks like only DNA work will finally solve all these mysteries.
Hi there,
ReplyDeleteI wonder if such darker birds (algeriensis, aucheri, whatever your mystery birds are) tend to predominate in more coastal regions, with true elegans more or less confined to inland, desert areas? Know that this seems to be the situation in Morocco at least. There's probably too much intergradation to suggest that elegans is a seperate species from the darker grey taxa, however, as backed up by your observations.
Harry,
ReplyDeleteThanks for your comment.
sorry about the slow reply but I have been away.
What you say about intergradation may well be true for the algeriensis/elegans complex in north west Libya. But a serious expert has told me that aucheri's DNA is too diffrent from elegans for them to interbreed. And the birds from north east Libya are much darker than algeriensis. it does beg the question why the elegans look darker than the pure bird. Another sub species?
I have re-read what İ saıd ın the last comment above. What İ saıd was clumsy. Here's a second go:
ReplyDeletealgeriensis and elgans are very sımılar ın terms of DNA. Thats why many people have them as sub specıes of the same maın specıes - desert grey shrıke. I thınk Harry ıs rıght about them undergoıng İNTRA (wıthin specıes) breedıng. I see some intermediates in north west Lıbya just lıke Harry does ın Morocco: However the case ıs dıfferent ın north east Lıbya: If the dark bırd ıs aucheri then any ıntermedıate bırds (aucheri/elegans) are INTER (between) specıes breed because the DNA are so dıfferent between aucheri and elegans (so I am told).
Although İ have a scıence PhD ıts not ın bıology but I know enough to guess thıs makes any aucheri/elegans hybrıds much less fertile. So goıng back to my orginal comment posted two days ago - thats what İ meant by interbreeding between aucheri and elegans ıs not possible.
What we really need ıs good DNA samples in Libya and a study on the fertility of intermediates/hybrids - any ornithologists out there?!