Structure and function of the tail show that the red hartebeest (Alcelaphus caama) is a different species from Coke's hartebeest (Alcelaphus cokii)

Many naturalists may assume that Coke's hartebeest (Alcelaphus cokii, and the red hartebeest (Alcelaphus caama, are mere subspecies of a single, widespread species (

And that Groves and Grubb (2011,, in elevating them to the status of full species, were overenthusiastic as taxonomic 'splitters'.

The 'lumping' view taken by iNaturalist may seem reasonable, given that many bovids vary subspecifically in details of colouration, and the shapes of their horns.

However, the distinction between cokii and caama runs deeper than it may at first seem. This is because

  • their tails differ in structure and function, and
  • the 'flight announcements' of ruminants - being basic to their anti-predator adaptations - tend to be more evolutionarily conservative than other aspects of their appearance and behaviour.

In order to understand the relevance of the tail, we first have to appreciate the part the tail plays in the broader context of adaptive colouration.

Please see


Both Alcelaphus cokii and Alcelaphus caama are candidates for the possession of bleezes on their hindquarters. These consist of large, pale, sheeny patches on the buttocks and haunches, contrasting with the dark of the tail-tassel.

By definition, bleezes tend to highlight the figures even when stationary, making them conspicuous to scanning predators even at some distance ( and

However, on closer scrutiny, the patterns are too different for cokii and caama to be regarded as mere subspecies.

This is because

These differences are so great that caama unambivalently possesses a bleeze, but the same cannot be said for cokii.

Of thousands of photos of cokii - with various illuminations - on the Web, the following makes the strongest possible case for conspicuous colouration in this species:

The following views of cokii also indicate a bleeze ( and and

However, this pattern results from not only depigmentation of the pelage, but also poorly-understood sheen/antisheen effects - which depend on the angle of the light. Furthermore, it tends to achieve conspicuousness only in posterior/posteriolateral view (

Another basic difference is that, in cokii, the pale extends to the legs, dissipating any pale/dark contrast within the figure as a whole ( and and

By contrast, in caama,

The following ( and and show that, in full profile, cokii can look so plain that it seems to exemplify cryptic colouration. This can hardly be said for adults of caama, in any illumination.


This dichotomy between cokii and caama is compounded by an obvious difference in caudal flags ( and This may apply particularly during stotting.

In cokii, the tail is not held raised during running. Instead, it tends to be tucked in.

Alcelaphus cokii, RUNNING:
Second photo in

By contrast, in caama the tail is raised to about a horizontal position. This makes for a conspicuous display, given that the dark tail-tassel is so large.

Alcelaphus caama, RUNNING:
Scroll to two photos in
Scroll in

My interpretation is that caama, but not cokii, qualifies as possessing a caudal flag, in an anti-predator context.


Both cokii and caama stot.

However, there is a previously overlooked, categorical difference in the function of the tail during stotting.

In cokii, the tail is not displayed, instead being hidden close to the buttocks. By contrast, in caama the tail is raised demonstratively to or above the horizontal position. This means that a caudal flag is activated, during stotting, only in caama.

Alcelaphus cokii, STOTTING:

Alcelaphus caama, STOTTING:


The tail differs so much, between caama and cokii, that it would be far-fetched to include them in a single species. This seems to have been overlooked by all previous authors.

(Groves and Grubb (2011) made no attempt to analyse adaptive colouration. Therefore, their reasons, for recognising cokii and caama as different species, differ from mine.

As I have shown in this Post, conspicuous colouration - at a scale relevant to anti-predator adaptations - is

Furthermore, this applies in terms of both




Publicado el octubre 9, 2022 10:52 TARDE por milewski milewski


Publicado por milewski hace casi 2 años
Publicado por milewski hace casi 2 años
Publicado por milewski hace casi 2 años

Even in posteriolateral view, the bleeze does not function - at least in human eyes - in certain illuminations, in Alcelaphus cokii. Does this have anything to do with the fact that this is a mature male?

Publicado por milewski hace casi 2 años


The following show activation of the caudal flag in intraspecific antagonism, in Alcelaphus caama:

The following suggest that Alcelaphus cokii differs somewhat in the raising of the tail:

Publicado por milewski hace casi 2 años

I learned a lot here from you! Then I went and compared my Alcelaphus buselaphus ssp. caama Observations. Thank you, Ruth

Publicado por grinnin hace casi 2 años

@grinnin Dear Ruth, you are most welcome, with kind regards from Antoni

Publicado por milewski hace casi 2 años

Nice juxtaposition of two different patterns in the category of bleezes:

Publicado por milewski hace casi 2 años

@davidbygott Hi David, Have you ever observed any kind of stotting (demonstrative running) in Alcelaphus cokii?

Publicado por milewski hace casi 2 años

Yes, I saw cokii stotting quite often in Serengeti. Probably even have photos of it. This was a bouncing gait with all 4 feet high off the ground and tail down, as I recall.

Publicado por davidbygott hace casi 2 años

@davidbygott Many thanks for this valuable information. If you were to Post those photos, they might be the only ones of their kind on the Web.

Publicado por milewski hace casi 2 años

The following are among the few I have found, showing the tail not raised during running by Alcelaphus caama. One sequence suggests that, when the animal gallops at full speed, the caudal flag is deactivated:

Publicado por milewski hace casi 2 años
Publicado por milewski hace casi 2 años

@davidbygott @beartracker

...and here is footage showing stotting in cokii, in the form of style-trotting:

Again, please note that the tail is tucked in, rather than being held out stiffly horizontal.

This is a previously overlooked difference - so categorical that it, in its own right, shows that cokii and caama are different species.

Publicado por milewski hace casi 2 años

In the following individual of caama, the pale of the bleeze excludes the base of the tail:

This is in contrast to the following, of cokii:

Publicado por milewski hace casi 2 años

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Some readers, inclined to accept the conventional view that caama is merely a subspecies of buselaphus, may assume that taxonomists have considered the differences in the tail-tassel, and interpreted them in a more objective way than I have.

However, I suggest that these differences - although obvious once noticed - have been overlooked.

For example, consider Skinner and Chimimba (2005), which is perhaps the most authoritative zoological work on the mammals of southern Africa.

(Please see

These authors describe caama in detail, down to the cross-sectional shape of the hairs (which, by the way, is kidney-like), all the various markings, and the gloss and sheen effects. This description runs to more than 400 words.

However, they do not even mention the tail-tassel, let alone state how different it is from all other hartebeests.

This seems to indicate a 'traditional blind spot' that has tended to be passed on from author to author, inadvertently resisting a realisation that can be achieved by any reader - simply by randomly picking any photo of caama and comparing it with any photo of any other 'subspecies' of hartebeest.

It is all the more remarkable that this particular 'blind spot' is for the very feature that caama itself advertises to us, by flagging its tail. And this flagging occurs not just in stotting and general running, but also in suckling, sparring, and other social/sexual interactions (, and even in the routine passing of urine/faeces.

Turning to another author who should have known better:

Jonathan Kingdon (, who is exceptional in combining the trained eye of a painter with the rigour of a zoologist, also completely overlooks the crucial difference, in his illustrations of all the hartebeests on page 599 of 'The Kingdon Field Guide to African Mammals', 2nd edition (2015).

His painting, incorrectly, depicts the tail of caama as identical to those of all other hartebeests.

The same mistake was made by Chris and Tilde Stuart, on page 148 of Field Guide to the Larger Mammals of Africa (3rd edition, 2006,

They incorrectly state: "Alcelaphus buselaphus...the simplest line is followed here with six distinct races which can be more or less separated on distribution, horn structure and colouration. All races have very similar...tails..."

Publicado por milewski hace casi 2 años

The tradition of field guides to African mammals was begun by C. T. Astley Maberly, with his 'The Game Animals of Southern Africa' (1963,

(At that time, so few photos were available that all the illustrations are sketches by the author.)

Like all subsequent authors, Astley Maberly erred in his description of the tail of the red hartebeest.

On page 73, he states: "tail...moderately haired with a thin crest of long hairs along upper surface of terminal half."

This is an apt description for Alcelaphus cokii, photos of which were more readily available at the time than photos of A. caama. However, it is a misleading description of the tail of A. caama.

Publicado por milewski hace casi 2 años

Robert Jacob Gordon (, a naturalist/explorer in the 1700's, recorded the following sketch of Alcelaphus caama:

Please note that his portrayal underplays the size of the tail.

In reality, the tail-tassel reaches the hock. So, the size of the tail, in profile, is threefold greater than depicted by Gordon.

Other early depictions that underplay the tail:

Publicado por milewski hace casi 2 años
Publicado por milewski hace casi 2 años

In Alcelaphus cokii, the suckling infant wags its tail but does not usually raise it:

In Alcelaphus caama, the sucking infant often raises its tail:

Publicado por milewski hace más de 1 año

The following are excerpts from my field-notes during a visit to Ithala Game Reserve in 2000. All are on the topic of caudal flagging in Alcelaphus caama.

"Near our lodgings, we encounter a group of 11 individuals of A. caama, which includes juveniles but has no adult male. In mild alarm, an adult female individual leads the way with a display trot (i.e. a trotting form of stotting), the tail held horizontal. When the animals flee more speedily, at a gallop, the tails are raised to the horizontal."

"As we walk up the road, we encounter a group of 10 individuals of A. caama in a slight valley. The animals take fright and run upslope for about 200 m, then stop to stare at us as we approach, then run on for a short distance, out of the way as we pass. At their first fright and galloping, the tails streamed out behind the body, i.e. held loosely more or less horizontally, as if by streamlining. While running, some of the group hold the tail erect, others hold the tail horizontally. I conclude that A. caama certainly partly erects the tail when galloping in alarm, and I think that the juveniles do this the most. When the group stands to stare, one or two individuals partly raise the tail, to about 45 degrees, as if to defecate/micturate, but apparently again a sign of alarm. I heard no snorting during this encounter. When the animals canter off again, some individual leave the tail inert, and some wag the tail actively and nervously as they run."

"On the way back, we encounter the same group of A. caama. The animals run in mild alarm, most of the adults with the tail horizontal, but the spiky-horned juveniles with the tail more or less erect. This difference between adults and juveniles seems to be consistent."

Publicado por milewski hace más de 1 año

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