Does the red hartebeest (Alcelaphus caama) qualify as hyperconspicuous?

'Hyperconspicuousness', in terms of adaptive colouration in ungulates, is defined by bold colouration in adults of both sexes, at all seasons, and also in infants.

It is in the conspicuousness of infants that the concept of 'hyper' arises, because it would be expected that this stage of growth, particularly vulnerable to predation, would not be exposed in the same way as the juvenile to mature stages.

I have previously described the takhi (Equus przewalskii) as hyperconspicuous (https://www.inaturalist.org/journal/milewski/66546-a-hyperconspicuous-horse-hiding-in-plain-sight#).

This is based on patterns so bold that the whole figure is conspicuous even when stationary, in both

• large-scale dark/pale contrasts in adults, and
• overall paleness in infants.

I have also pointed out that a prime example of hyperconspicuous colouration, among ruminants, is Connochaetes mearnsi.

In my recent scrutiny of the red hartebeest (Alcelaphus caama), it has dawned on me that this species may possibly also qualify as possessing hyperconspicuous colouration (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=414565863).

The reasons why I have been slow to realise this include:

• lumping of caama with other forms of hartebeest has tended to obscure the nature of caama as a specific entity,
• categorisation of hartebeests as 'hiders' in infancy has tended to obscure the fact that, even after the brief hiding period, infants of caama remain conspicuously pale (https://www.inaturalist.org/observations/34703540), and
• individual variation in colouration in caama is great enough to complicate the interpretation of photos.

I can now make the following case, by means of comparative illustrations with the takhi.

The colouration of adults in Alcelaphus caama is conspicuous, even when stationary, owing to a combination of

• a bleeze on the hindquarters, that is visible in both posterior and lateral views,
• sheen on the pelage, and
• upright horns and a dark face in maturity (https://www.masterfile.com/image/en/841-03060851/red-hartebeest-alcelaphus-buselaphus-kalahari-gemsbok), so that the figure tends to stand out even in anterior view with the bleeze out of sight.

Infants emerge from hiding at only two weeks old, when their colouration is still distinctively pale, accentuated by a precocially dark tail.

Furthermore, the rest of the bleeze on the hindquarters is also noteworthy in its precociality, starting to develop before the ground-colour darkens to the medium tone seen in adults. Indeed, in at least some individual infants, the bleeze starts to appear before the umbilical cord disappears (https://www.shutterstock.com/image-photo/newborn-red-hartebeest-looking-over-his-510145570).

In adults of the takhi, there is no particular bleeze. However, there is dark/pale contrast among the lower legs, tail, mane, and nose (all dark), and flanks, buttocks, and muzzle (all pale) - which combine to make the figure conspicuous as a whole, from all perspectives:

https://www.inaturalist.org/observations/71816485
https://www.flickr.com/photos/danielahartmann/10175540443
https://www.naturalhistoryonthenet.com/Mammals/PrzewalskisHorse.htm
https://www.shutterstock.com/image-photo/przewalskis-horse-equus-ferus-przewalskii-known-1257519664
https://www.globetrotting.com.au/horse-breed-przewalskis-horse/

In adults of the red hartebeest, there is a particular bleeze (consistent among individuals), consisting of

• sheeny pale on the buttocks and haunches (https://matlabas.co.za/red-hartebeest/ and https://www.flickr.com/photos/berniedup/32453056162), extending to the rump, near the base of the tail (https://www.shutterstock.com/image-photo/red-hartebeest-south-africa-2191092581),
• sheen on the flanks (https://www.shutterstock.com/image-photo/red-hatebeest-standing-on-karoo-grass-60090565), extending the pale in an anterior direction in some illuminations (https://www.bigstockphoto.com/image-331206067/stock-photo-red-hartebeest%2C-alcelaphus-buselaphus-caama-or-alcelaphus-caama-walking-in-dry-kalahari-sand-in-kala and https://www.picfair.com/pics/04966390-red-hartebeest-in-the-grass), and
• dark in the tail and, to variable extent and degree, on the ventral part of the haunches (https://upload.wikimedia.org/wikipedia/commons/d/d7/Red_Hartebeest_%28Alcelaphus_buselaphus%29_territorial_male_..._%2851087569821%29.jpg and https://somethingovertea.files.wordpress.com/2020/01/addoredhartebeest4.jpg and https://www.shutterstock.com/image-photo/wild-red-hartebeest-alcelaphus-buselaphus-caama-506756440).

This bleeze is absent in newborns, and is somewhat 'dimmed' in mature males.

https://www.mindenpictures.com/stock-photo-red-hartebeest-alcelaphus-buselaphus-caama-with-young-kgalagadi-naturephotography-image90824199.html

https://www.pond5.com/stock-footage/item/84814271-red-hartebeest-antelope-suckling-calf-kalahari-desert-south

The following shows that the bleeze starts to develop in the infant: https://www.masterfile.com/image/en/6119-08242958/red-hartebeest-alcelaphus-buselaphus-calf-karoo-national.

https://www.shutterstock.com/image-photo/red-hartebeest-herd-kgalagadi-transfrontier-park-223525426

https://www.shutterstock.com/image-photo/red-hartebeest-kgalagadi-transfrontier-national-park-60359128

https://www.shutterstock.com/image-photo/red-hartebeest-bush-etosha-nationparc-namibia-2168682787

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=18209831

https://www.shutterstock.com/image-photo/red-hartebeest-antelope-alcelaphus-buselaphus-young-1639636957

In fully mature males, the pale of the bleeze tends to darken, but overall conspicuousness tends to be maintained by the degree of overall darkness (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=257384153 and https://www.shutterstock.com/image-photo/red-hartebeest-kgalagadi-south-africa-2160034269 and https://realorasafaris.co.za/product/red-hartebeest/ and https://www.posterazzi.com/red-hartebeest-etosha-national-park-namibia-africa-poster-print-by-jaynes-gallery-item-varpddaf31bja0119/ and https://fineartamerica.com/featured/red-hartebeest-belinda-greb.html).

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

Whether Alcelaphus caama qualifies as hyperconspicuous, or not, may depend on three main questions, viz.

• are infants better-described as 'followers' or 'hiders',
• is the colouration of infants better-described as conspicuous or inconspicuous, and
• are mature males, in their prime, conspicuous despite some dimming of the bleeze on the hindquarters?

Skinner and Smithers (2005), citing Kok (1975), state: "mothers recognise their calves at distances up to 300 m and if the herd takes flight the calves rejoin therir mothers in flight...calves that are unable to keep up with the herd fall flat on the ground and lie still, as an avoidance reaction to following predators."

Infants are pale in human eyes, but clearly not pale enough to negate their tactic of hiding under some circumstances. Therefore, the question that seems crucial is whether, infants have any features conspicuous to the eyes of ungulates, in ultraviolet, that tend to be obscured when the figure lies flat on the ground.

Mature males, in their prime, seem to become dark enough to remain conspicuous, despite the loss of some of the conspicuous paleness of the bleeze (see https://www.inaturalist.org/journal/milewski/71379-the-red-hartebeest-shows-subtle-convergence-with-a-coexisting-giraffe-in-darkening-for-masculine-conspicuousness#).

Alcelaphus cokii seems to differ from A. caama in that infants do not differ much from their mothers in the ground-colour (https://www.bigstockphoto.com/image-366065119/stock-photo-young-hartebeest-leaves-mother-in-sunlit-savannah).

Posted on October 15, 2022 12:08 AM by milewski