The year is winding down, but there seems so much to do still. Accordingly this will be a fairly low-key post, based on a comment I heard with regard to our African adventure earlier this year, both while there from our companions on the East African tour, and since getting home. "But I thought there was only one zebra (ostrich, giraffe etc)!"
Fair enough too; we usually just refer to such animals in one-word terms, strongly implying that this is exactly the case. 'Zebras' for instance; even if we're aware of the more formal name of Plains or Common Zebra we usually tend to just go for friendly informal 'zebra'.
This is quite understandable; almost any zebra that you're likely to see either in captivity or in the wild in Africa will probably belong to this species. This post is intended as an introduction to a few often unsuspected animals, not an in-depth study, but a couple of questions probably need to be asked about this one. Why 'zebra', and why the stripes? Unfortunately if you really wanted to know the definitive answer to either of these questions, you've come to the wrong place. My trusty old big Oxford Dictionary reports that it appeared in English for the first time in 1600, in a work translated from Portuguese. It suggests that the word originated in a Congolese language and appeared in similar forms around the same time in Italian, French and Spanish too. However I understand that other sources suggest a possible Latin origin, though the nexus seems pretty vague. I'm inclined to go with the Oxford, based on a long relationship.
Plains Zebra and foal (and bonus Yellow-billed Oxpecker), Tarangire NP, Tanzania. The foal's stripes will darken age. |
And the stripes? There is an array of suggestions, the most popular of which relate to camouflage, either referring to broken shadows or the 'dazzling' effect of swirling patterns of fleeing animals. Social aspects have been mooted, wherein stripes stimulate a zebra to groom other zebras, or the unique patterns of individuals assist in recognition. A couple of more recent suggestions, both evidence-based, are interesting. One shows that biting flies, which rely on homing in on polarised light, are confused by the stripey patterns. Another demonstrates that black stripes can be up to 10 degrees C hotter than adjacent white ones, which sets up small air convection currents which in turn assist in evaporative cooling. Have fun working your way through all those options!
We do know about the quagga part of the name though. This is a Khoekhoe word (once referred to as Hottentot) from South Africa, referring to an abundant sub-species which was hunted to extinction by 1880. Only one photograph exists (from an animal in London Zoo), plus 20-odd skins. Curiously the Quagga lacked stripes over most of the back half of its body. Which brings us to the point of this post; there isn't just one 'zebra' and this isn't just true at the subspecies level. Before we look at the other two zebra species, let's see what differentiates the Plains Zebra from them.
While the Plains Zebra is found in much of eastern Africa, and across northern Namibia to the Atlantic, the Mountain Zebra Equus zebra is limited to scattered mountain populations in southern South Africa and western Namibia. In the 1930s there were perhaps only 100 left, but numbers have increased with sustained conservation programs.
The third zebra species lives in the opposite corner of the continent, scattered in a few reserves in northern Kenya and Ethiopia, while it has has been extirpated in Djibouti, South Sudan, Eritrea and Somalia. Grevy's Zebra E. grevyi is the largest living wild horse, and rangier than the other zebras. This was the hippotigris ('tiger horse') which appeared in Roman arenas and parades. It is listed as Endangered, though populations seems to have stabilised.
But ostriches? Surely there's only one ostrich?! No, there are actually two. The Common Ostrich Struthio camelus has two quite separate big ranges, across southern Africa, up from northern South Africa, and across a huge swathe of the Sahel from the Red Sea to the Atlantic with a 'tongue' of occupation down through Kenya and Tanzania.
Common Ostriches, Tarangire NP, Tanzania. The two ostriches are the world's largest birds; a male can be nearly three metres tall and weigh over 150kg. Females and immature birds are very similar. |
The Somali Ostrich S. molybdophanes was described as a separate species back in 1883 but this was rapidly rejected, and until this millennium it was regarded as a sub-species of Common Ostrich. Only in 2014 was it reinstated as a full species, based on various physical and genetic characters, and the fact that the two live side by side in Ethiopia.
There are other differences too.
Add caption |
At Shaba we encountered another Horn of Africa relative of a widespread and well-known species too. The Common Warthog Phacochoerus africanus is a familiar pig across much of sub-Saharan Africa.
Common Warthog, Ngorongoro Crater, Tanzania. It really is a remarkable creature. |
In northern Kenya, Ethiopia and Somalia is a closely related warthog, an arid land specialist, the Desert Warthog P. aethiopicus. It's been known for a long time, but it's not a part of the world that most nature-watchers tend to visit.
And finally I mentioned giraffes. No, it's OK, there really is only one Giraffe species Giraffa camelopardalis. Well, so far anyway; a number of reputable recent studies strongly suggest there are more. The eminent - and sadly recently late - Colin Groves in a 2011 publication believed there were eight species! We'll stick with the orthodoxy for today though, which generally recognises eight subspecies. Here are some of them; they are really quite distinctive.
Masai Giraffe G. c. tippelskirchi, Serengeti NP, Tanzania. The spots here are very 'splintered' and go right down to the hoofs. Tanazania and southern Kenya. |
As I said, these very different giraffes are still regarded as the one species, but I have a feeling that that may not be the case for much longer.
Well, not for the first time that's probably more than I meant to say, but I hope you've found something to interest you here. If nothing else you may have met some special animals whose existence you may not hitherto have known about. Either way they're worth considering.
Enjoy the last days of 2019, and may 2020 bring you lots of natural history adventuring! I'll be back once more before the end of the year, for my annual year's highlights, via one photo per month.
NEXT POSTING TUESDAY 31 DECEMBER
(And remember that you can get a reminder when the next post appears by putting your email address in the Follow by Email box in the top right of this screen.
And I'd love to receive your comments - it's easy and you don't need to sign in!)
(And remember that you can get a reminder when the next post appears by putting your email address in the Follow by Email box in the top right of this screen.
And I'd love to receive your comments - it's easy and you don't need to sign in!)
2 comments:
Another interesting and informative post Ian. Thank you for posting your excellent articles in 2019 and I look forward to your 2019 roundup post. Wishing you a merry Christmas and a happy new year, Roman
Thanks Roman; it's good to hear from you, and I greatly appreciate your supportive comments. A happy and peaceful Christmas to you, and I hope 2020 starts very well and naturally for you! See you next year.
Post a Comment