@tonyrebelo @ludwig_muller @jeremygilmore @tandala @michalsloviak @oviscanadensis_connerties @geichhorn @paradoxornithidae @beartracker @capracornelius @colin25 @chewitt1 @jakob @jwidness @johnnybirder @matthewinabinett @davidbygott @zarek @koosretief @dejong @koenbetjes @simontonge @muir
See https://www.inaturalist.org/journal/milewski/71135-structure-and-function-of-the-tail-show-that-the-red-hartebeest-alcelaphus-caama-is-a-different-species-from-coke-s-hartebeest-alcelaphus-cokii# and https://www.inaturalist.org/journal/milewski/71167-subtleties-of-adaptive-colouration-in-alcelaphus-cokii-and-alcelaphus-caama#.
On scrutiny, it is surprising that any naturalist, familiar with Alcelaphus cokii (https://www.deviantart.com/okavanga/art/Hartebeest-580725609) and Alcelaphus caama (https://www.alamy.com/stock-photo-the-family-alcelaphus-buselaphus-caama-the-red-hartebeest-is-a-species-119959450.html), continues to see these as belonging to a single species.
Contrary to the conventional view (https://upload.wikimedia.org/wikipedia/commons/4/49/Alcelaphus_recent.png), these are clearly different enough to be separate species, in the following ways.
ANATOMY
cokii male:
https://stock.adobe.com/search?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=1&filters%5Bcontent_type%3Atemplate%5D=1&filters%5Bcontent_type%3A3d%5D=1&filters%5Bcontent_type%3Aaudio%5D=0&filters%5Binclude_stock_enterprise%5D=0&filters%5Bis_editorial%5D=0&filters%5Bfree_collection%5D=0&filters%5Bcontent_type%3Aimage%5D=1&k=%22coke%27s+hartebeest%22&order=relevance&safe_search=1&limit=100&search_page=3&search_type=pagination&get_facets=0&asset_id=493604898 and https://stock.adobe.com/search?k=%22coke%27s+hartebeest%22&asset_id=87302482
cokii female:
https://www.inaturalist.org/observations/57486416
caama male:
https://www.inaturalist.org/observations/20885285 and https://www.shutterstock.com/image-photo/adult-red-hartebeest-southern-african-savanna-653300923
caama female:
https://www.shutterstock.com/image-photo/hartebeest-hron-head-detail-grass-namibia-1676326405
BEHAVIOUR
COLOURATION
DISCUSSION
The naturalist's eye tends naturally to be drawn to the shapes of the horns.
However, it is only when one sees past the obvious differences between cokii and caama, in the orientation of the horns, that the true depth of the interspecific differences is noticed.
There is so little sexual dimorphism in Alcelaphus cokii that it is hard to find, among the thousands of photos on the Web, any view clearly comparing adult male and adult female within a single frame. The closest are:
However, Alcelaphus caama shows obvious sexual difference in the size of the horns (https://stock.adobe.com/search?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=1&filters%5Bcontent_type%3Atemplate%5D=1&filters%5Bcontent_type%3A3d%5D=1&filters%5Bcontent_type%3Aaudio%5D=0&filters%5Binclude_stock_enterprise%5D=0&filters%5Bis_editorial%5D=0&filters%5Bfree_collection%5D=0&filters%5Bcontent_type%3Aimage%5D=1&k=hartebeest&order=relevance&safe_search=1&limit=100&search_page=49&get_facets=0&search_type=pagination&asset_id=203749833).
The differences are even greater in the case of the tail.
In the case of the tail alone, the differences between cokii and caama in anatomy and display are such that they could belong to different genera, not just different species.
The far greater demonstrativeness of the tail, in caama than in cokii, extends to adaptive colouration at the scale of the whole figure:
Comments
The following, of Alcelaphus caama, may seem to show brindling on the flanks, but I suspect that this is merely a shadow effect of the ribs:
https://www.inaturalist.org/observations/10837282
https://www.masterfile.com/image/en/400-09223149/red-hartebeest-antelope-alcelaphus-buselaphus-with-suckling
https://www.shutterstock.com/image-photo/black-wildebeest-whitetailed-gnu-connochaetes-gnou-1683605734
The following sequence is unusual in that it shows caama running without holding up the tail:
https://www.shutterstock.com/image-photo/hartebeest-running-savannah-1711990042 and https://www.shutterstock.com/image-photo/hartebeest-running-savannah-1711990045
https://www.shutterstock.com/image-photo/hartebeest-alcelaphus-buselaphus-running-etosha-national-1559768366
https://www.shutterstock.com/image-photo/wild-antelopes-african-zebra-gazelle-hartebeest-1682548003
Infants of Alcelaphus caama, showing darkness and flagging of the tail:
https://www.shutterstock.com/image-photo/young-hartebeest-foal-running-abandonment-youth-1461604730
https://www.shutterstock.com/image-photo/red-hartebeest-calf-southern-african-savanna-1371081983
Further illustrations of the caudal flag in adults of Alcelaphus caama:
https://www.shutterstock.com/image-photo/red-hartebeest-standing-mud-kgalagadi-transfrontier-645605860
https://www.shutterstock.com/image-photo/solitary-red-hartebeest-alcelaphus-buselaphus-standing-787159390
https://www.shutterstock.com/image-photo/three-young-red-hartebeest-calves-known-1357995743
Stotting in Connochaetes gnou:
https://www.shutterstock.com/image-photo/bucking-black-wildebeest-whitetailed-gnu-connochaetes-1554743708
Additional illustrations of size of horns in adult males of Alcelaphus caama:
https://www.inaturalist.org/observations/27391460
https://www.mediastorehouse.com.au/ardea-wildlife-pets-environment/hartebeest-kongoni-pair-mating-1301280.html#openModal
http://treatment.plazi.org/id/03F507139919FFA2034CF53BF8F6F407
http://cannundrum.blogspot.com/2014/07/cokes-hartebeest.html
https://www.agefotostock.com/age/en/details-photo/hartebeest-alcelaphus-buselaphus-female-with-cub-standing-in-savanna-masai-mara-park-kenya/YS1-1673146
https://www.inaturalist.org/observations/110571431
https://www.istockphoto.com/photo/eland-antelope-on-the-serengeti-gm1424956807-469553531?phrase=eland
https://www.istockphoto.com/photo/large-eland-bull-walks-across-the-green-grasslands-of-the-masai-mara-kenya-gm1349116472-425845129?phrase=eland
https://www.istockphoto.com/photo/eland-in-zimbabwe-gm1425949522-470278150?phrase=eland
https://www.researchgate.net/figure/Historical-distribution-early-twentieth-century-of-hartebeest-subspecies-across-Africa_fig1_227419377
https://www.warwicktarboton.co.za/other%20crea%20pgs/331RHart.html
The following shows activation of the caudal flag in Alcelaphus caama, in a social/sexual, not anti-predator, context:
https://www.stuporterphotography.com/image/I0000zJVlHwxOnLE
The following shows that the caudal flag is activated during running, even after the trauma of injury, in Alcelaphus caama:
https://www.wildcard.co.za/cheetah-red-hartebeest-hunt-mountain-zebra/
https://www.pinterest.com.au/pin/red-hartebeest--108367934762868533/
The following show the sexual dimorphism in Alcelaphus caama:
https://www.chiswickauctions.co.uk/auction/lot/200-two-red-hartebeest-skulls-and-horns/?lot=150646&sd=1
https://www.alamy.com/stock-photo-red-hartebeest-alcelaphus-buselaphus-mating-south-africa-18244684.html
https://www.ewt.org.za/wp-content/uploads/2019/02/2.-Red-Hartebeest-Alcelaphus-buselaphus-caama_LC.pdf
Activation of caudal flag in infants of Alcelaphus caama:
https://www.naturefootage.com/video-clips/RHO190523_0134/red-hartebeest-alcelaphus-buselaphus-caama-foal-runs-to-mother
Alcelaphus cokii
male
https://www.inaturalist.org/observations/92815095
female
https://www.inaturalist.org/observations/98468707
ADDITIONAL PHOTOS of caudal flag in Alcelaphus caama, in anti-predator context:
https://www.agefotostock.com/age/en/details-photo/red-hartebeest-alcelaphus-buselaphus-selbornei-adult-running-tswalu-game-reserve-kalahari-northern-cape-south-africa-africa/JHS-S18209
https://www.shutterstock.com/image-photo/young-red-hartebeest-alcelaphus-buselaphus-running-2166233823
https://www.shutterstock.com/image-photo/red-hartebeest-alcelaphus-buselaphus-running-grassland-2035937903
https://www.inaturalist.org/observations/138532246
https://www.inaturalist.org/observations/38129078
https://www.agefotostock.com/age/en/details-photo/red-hartebeest-running-kruger-national-park-mpumalanga-south-africa/AAI-1-PHGN-0006
https://www.agefotostock.com/age/en/details-photo/red-hartebeest-alcelaphus-buselaphus-caama-adult-running-across-a-dirt-road-close-of-day-kgalagadi-transfrontier-park-northern-cape-south-africa-africa/ZI6-3564222
https://www.agefotostock.com/age/en/details-photo/red-hartebeest-alcelaphus-buselaphus-running-south-africa/BWI-BLWS016733
https://stock.adobe.com/au/search?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=1&filters%5Bcontent_type%3Atemplate%5D=1&filters%5Bcontent_type%3A3d%5D=1&filters%5Bcontent_type%3Aaudio%5D=0&filters%5Binclude_stock_enterprise%5D=0&filters%5Bis_editorial%5D=0&filters%5Bfree_collection%5D=0&filters%5Bcontent_type%3Aimage%5D=1&k=%22red+hartebeest%22&order=relevance&safe_search=1&limit=100&search_page=12&search_type=pagination&get_facets=0&asset_id=100627997
caudal flagging in Connochaetes gnou
https://es.123rf.com/photo_161045244_el-%C3%B1u-negro-cruza-la-cola-silbante-de-la-bandeja-de-grava.html?vti=mch23vm5bp6yx1g30l-1-38
https://es.123rf.com/photo_161045130_el-%C3%B1u-negro-cruza-la-cola-silbante-de-la-cacerola-rocosa.html?vti=mswawdspfw17iic3hq-2-2
In thousands of photos of Alcelaphus caama, the following is the only one that shows a trace of brindling on the flank:
https://www.flickr.com/photos/berniedup/32453056162
There is considerable variation in the length of the horns, in both sexes. The following show the maximum length of the horns in females:
https://www.shutterstock.com/image-photo/red-hartebeest-african-antelope-savannas-south-392676568
https://stock.adobe.com/au/search?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=1&filters%5Bcontent_type%3Atemplate%5D=1&filters%5Bcontent_type%3A3d%5D=1&filters%5Bcontent_type%3Aaudio%5D=0&filters%5Binclude_stock_enterprise%5D=0&filters%5Bis_editorial%5D=0&filters%5Bfree_collection%5D=0&filters%5Bcontent_type%3Aimage%5D=1&k=%22red+hartebeest%22&order=relevance&safe_search=1&limit=100&search_page=12&search_type=pagination&get_facets=0&asset_id=66707929
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