Hippotragin bovids in posteriolateral view: an interspecies comparison of adaptive colouration, part 1

I was struck with the graphic pattern of colouration in https://www.istockphoto.com/photo/gemsbok-oryx-in-the-savannah-gm1409738737-460184782?phrase=bongo+antelope+antelope+animal+pattern and https://www.istockphoto.com/photo/gemsbok-oryx-in-the-savannah-gm1409738770-460184781?phrase=bongo+antelope+antelope+animal+pattern.

This depicts a hippotragin bovid, namely Oryx gazella (https://www.inaturalist.org/taxa/42308-Oryx-gazella), standing in a posteriolateral perspective.

It is as if the colouration is designed to advertise the animal (and please note how conspicuous the seven additional figures are in the distance).

Stimulated by this photo, I was curious to see how the various relatives of O. gazella appear, in similar posteriolateral view, under similar illumination.

So, I have chosen the clearest photos of adults available on the Web, to make a species-by-species comparison of all extant hippotragin bovids (https://www.inaturalist.org/observations?place_id=any&taxon_id=846296&view=species).

First, let us try to be precise about the pattern in O. gazella.

This consists of the following elements/features:

conspicuously dark rump and tail, the tail tassel being large and full enough that its darkness affects the appearance of the whole figure,
conspicuously pale - partly owing to sheen - buttocks and haunches,
pale on the visible part of the abdomen, offset by a dark band on the lower flanks,
dark un the upper legs (both fore and hind), offset by pale on the lower legs, and
crisp/stark borders between dark and pale, producing striking contrasts.

There is no difference in colouration between the sexes in O. gazella.

In the case of other species of hippotragins, are the same elements/features present? If not, are there alternative elements/features that confer conspicuousness?

Throughout the following, I disregard the colouration on the head - despite this being graphic and conspicuous in most species.

ORYX GAZELLA

Additional photos of O. gazella:

https://www.123rf.com/photo_200391229_a-vertical-shot-of-a-gemsbok-on-a-field.html

https://www.dreamstime.com/stock-photos-gemsbok-oryx-namibia-image14168073

https://www.123rf.com/photo_128094873_the-oryx-is-a-large-antelope-that-lives-mainly-in-semi-arid-desert-like-habitat-in-southern-africa.html

ORYX CALLOTIS

This species is surprisingly different from O. gazella. There are few conspicuous elements/features, mainly because pale pelage is absent.

The dark features are retained in reduced form viz.

the tassel of the tail is as dark as in O. gazella, but smaller,
the base of the tail is not dark,
dark on the upper legs is reduced on the forelegs, and absent on the hindlegs,
the dark flank-band is narrowed,
the dark on the rump is so reduced that the relictual mark is hardly noticeable, and
even those dark features that remain are bereft of any contrast with pale.

https://www.inaturalist.org/observations/122981862

https://www.naturepl.com/stock-photo-fringe-eared-oryx-oryx-beisa-callotis-female-looking-back-towards-nature-image01529829.html

https://stock.adobe.com/images/close-up-of-a-fringe-eared-oryx-oryx-beisa-callotis-with-long-black-tasseled-tail-muscular-fawn-coloured-body-black-bands-white-muzzle-and-long-curved-horns-standing-in-field-of-dry-gold-grass/243899581

ORYX BEISA

This species, although closely related to O. callotis, is relatively conspicuous in posteriolateral view.

This is because

the pale surface seen on the buttocks of O. gazella is somewhat present (sometimes extending to the haunches, according to sheen and individual variation),
the dark/pale contrasts on flank/abdomen and upper/lower foreleg, although less graphic than in O. gazella, are approximately present, and
a new contrast (constituting an ulnar flag) has appeared on the upper forelegs, viz. between the dark above the carpals and the whitish of the posterior surface below the elbow.

Despite the introduction of an ulnar flag, O. beisa is not as boldly marked as O. gazella. This is because, as in O. callotis,

the dark tail tassel is relatively small,
dark is absent from the rump, the base of the tail, and the upper hindleg, and
the abdomen, although pale, is not white in most individuals (https://www.agefotostock.com/age/en/details-photo/beisa-oryx-oryx-beisa-in-semi-desert-samburu-national-reserve-kenya/YP6-2535537).

https://www.inaturalist.org/observations/68999611

https://www.inaturalist.org/observations/86704883

https://www.safaribookings.com/awash/wildlife-photos#photo2

https://www.shutterstock.com/image-photo/beisa-oryx-adult-savannah-masai-mara-1614352966

https://www.gettyimages.co.uk/detail/news-photo/portrait-of-a-beisa-or-east-african-oryx-oryx-gazella-beisa-news-photo/1371856552?adppopup=true

https://www.gettyimages.co.uk/detail/photo/beisa-oryx-royalty-free-image/sb10063797f-001?phrase=beisa+antelope+oryx&adppopup=true

https://www.sciencephoto.com/media/643368/view/beisa-oryx-herd-in-awash-national-park

https://www.inaturalist.org/observations/6941058

ORYX DAMMAH

Virtually none of the elements/features seen in O. gazella is retained in conspicuous form. The torso of O. dammah is noticeably pale, but there is no striking pattern in posteriolateral view.

The tail tassel is as large and full as in O. gazella, but it is not emphasised by colouration. A transverse pattern at the junction of buttocks and upper hindlegs is individually variable, and too faint to be conspicuous.

As in O. callotis, a new element has appeared just below the elbow. In this case, it consists of a fairly dark horizontal band, contrasting somewhat with the adjacent pale surfaces. However, this is probably too faint to qualify as a flag.

https://www.zooborns.com/.a/6a010535647bf3970b02788013d6cb200d-popup

https://www.natureplprints.com/popular-themes/creative-set-10/scimitar-horned-oryx-oryx-dammah-18854306.html

https://www.inaturalist.org/observations/177347131

https://www.petersenshunting.com/editorial/right-gear-for-scimitar-oryx/469527

https://www.ephotozine.com/photo/scimitar-horned-oryx----67372091

scroll in https://www.discountafricanhunts.com/africananimals/scimitar-horned-oryx.html

https://www.zoochat.com/community/media/scimitar-horned-oryx-watatunga-27-11-22.623211/

ORYX LEUCORYX

This species has colouration starker than that of O. dammah, and categorically different from other species of Oryx. The torso and hindquarters are conspicuously pale as a whole, without there being a distinct pattern as seen in O. gazella.

The tail is potentially conspicuous, because the tassel is large and dark enough, in some individuals, to qualify as a caudal flag. However, the tail tassel, when at rest, tends to blend with the dark of the upper hindlegs.

Contrast is provided by the dark on the forelegs and lower hindlegs. However, this is subsidiary/peripheral, in posteriolateral view, to the overall pallor of the figure.

https://www.inaturalist.org/observations/138996183

https://www.inaturalist.org/observations/20688323

https://www.inaturalist.org/observations/15048806

https://zooinstitutes.com/animals/arabian-oryx-biblical-zoological-garden-3667.html

HIPPOTRAGUS NIGER

This species has

These form a striking pattern, different from that seen in any species of Oryx.

(Please see https://www.inaturalist.org/journal/milewski/85930-sexual-and-ontogenetic-development-of-the-ischio-abdominal-bleeze-of-the-southern-sable-antelope-hippotragus-niger-niger#)

However, this species is odd among hippotragins in having sexually dimorphic colouration.

This sexual dimorphism is complicated, because

it increases from the southernmost subspecies (nominate niger) to the northernmost subspecies (roosevelti),
it decreases with age in females, which emulate males by tending to darken progressively with maturity, and
the tail is the first dark surface to appear on the hindquarters.

In posteriolateral view, there tends to be a transverse pattern linking the white of the buttocks (https://www.gettyimages.com.au/detail/photo/sable-antilope-chobe-national-park-royalty-free-image/1271310163?phrase=sable+antelope&adppopup=true) and the crisply-defined white of the abdomen.

The haunches tend to darken last, affirming the transverse pattern linking buttocks with abdomen (male: https://www.alamy.com/sable-hippotragus-niger-dronfield-nature-reserve-northern-cape-south-africa-image417606909.html and female: https://www.inaturalist.org/observations/143707556 and https://www.alamy.com/sable-antelope-hippotragus-niger-in-the-dessert-captive-distribution-africa-image502160637.html?imageid=D3126C1B-9D6C-4357-9284-D2327393EFDB&p=816634&pn=7&searchId=2e53d2ed5b881c2af6863ceb6110b704&searchtype=0).

Males:

https://www.inaturalist.org/observations/124731407

https://www.inaturalist.org/observations/9087513

https://www.dreamstime.com/sable-antelope-ram-curved-horns-used-breeding-massive-image272684941

https://www.inaturalist.org/observations/175931666

https://www.gettyimages.com.au/detail/photo/sable-antelope-royalty-free-image/WL003545?phrase=sable+antelope&adppopup=true

https://www.gettyimages.fi/detail/valokuva/chobe-national-park-sable-antelope-rojaltivapaa-kuva/977797858?adppopup=true

Females:

adult but not fully mature https://www.inaturalist.org/observations/111519509

fully mature https://www.inaturalist.org/observations/108545995

fully mature https://www.peaceparks.org/sable-antelope-back/

Both sexes together:

https://www.inaturalist.org/observations/64866733

HIPPOTRAGUS EQUINUS

In this species, there is a noticeable but fairly simple - and vertically aligned - pattern (https://www.alamy.com/a-roan-antelope-hippotragus-equinus-in-the-grasslands-of-the-nyika-plateau-nyika-national-park-in-malawi-image344123120.html?imageid=2E70F0EB-F7E4-4352-B0BC-632D6CF4564E&p=1249180&pn=5&searchId=5ed1e1ea051df95555f6aaed35fb537c&searchtype=0), in all subspecies.

This does not qualify as a bleeze, but can perhaps be called a caudo-ischial flag.

The main elements, which are among those present in O. gazella, are

pale buttocks, contrasting with
dark on the base and stalk of the tail.

The result is fairly conspicuous, despite

the blurring of the pale of the buttocks into the ground-colour,
the small size of the dark tail tassel, and
the slightness of dark on the rump, where it is restricted to the mid-line.

Adding slightly to the pattern are

the paleness of the abdomen,
the tendency to darkness on the forelegs, and
the darkness of the mane at the withers.

https://www.istockphoto.com/photo/a-rare-roan-antelope-in-natural-habitat-south-africa-gm1628183210-532254021?phrase=roan+antelope

https://www.shutterstock.com/image-photo/stunning-roan-antelope-hwange-national-park-1186020874

https://www.shutterstock.com/image-photo/rare-roan-antelope-hippotragus-equinus-natural-2350085305

https://www.inaturalist.org/observations/25801218

https://afrizim.com/travel-guides/animals/roan.html

https://www.inaturalist.org/observations/45668933

https://www.inaturalist.org/observations/142404442

https://www.inaturalist.org/observations/141947502

https://www.inaturalist.org/observations/126107841

https://www.alamy.com/stock-photo-roan-antelope-and-oxpecker-busanga-plains-kafue-national-park-zambia-33318485.html?imageid=37EBE169-45F1-4E06-96DF-32556949EF27&p=94689&pn=5&searchId=5ed1e1ea051df95555f6aaed35fb537c&searchtype=0

https://www.inaturalist.org/observations/9979094

https://www.inaturalist.org/observations/66772812

https://www.inaturalist.org/observations/66512693

https://www.inaturalist.org/observations/61771283

https://www.inaturalist.org/observations/36915943

https://www.inaturalist.org/observations/30461738

https://www.shutterstock.com/image-photo/roan-antelope-standing-on-grassland-2358738767

https://www.shutterstock.com/image-photo/back-view-isolated-roan-standing-on-520587406

https://www.shutterstock.com/image-photo/rare-roan-antelopes-hippotragus-equinus-natural-2043032120

https://www.istockphoto.com/photo/roan-antelope-gm598061570-102470709?phrase=roan+antelope

https://www.alamy.com/botswana-ngamiland-okavango-delta-moremi-game-reserve-roan-antelope-image245856231.html?imageid=9A6F2149-E8C0-479C-B70D-1AD54C64A91E&p=830292&pn=5&searchId=5ed1e1ea051df95555f6aaed35fb537c&searchtype=0

The following individual of H. equinus koba (https://www.alamy.com/stock-photo-roan-antelope-hippotragus-equinus-adult-w-regional-park-w-transborder-59189738.html?imageid=66386DE1-36D7-4F8B-A3A8-783EC28B2A82&p=86574&pn=5&searchId=5ed1e1ea051df95555f6aaed35fb537c&searchtype=0) is unusual in lacking any dark pelage on the hindquarters.

ADDAX NASOMACULATUS

This species is odd among bovids, and unique among hippotragins, in having different colouration in summer vs winter (https://twitter.com/hallaboutafrica/status/1604719030862237696).

Furthermore, the winter coat is odd in that

there are sharp borders between the ground colour on the flanks and the whitish on the hindquarters and abdomen (https://www.istockphoto.com/photo/the-african-addax-gm153697670-15130906?phrase=addax+antelope and https://www.istockphoto.com/photo/the-african-addax-gm153775912-15012541?phrase=addax+antelope), and
the tail tassel, which is remarkably small and always inconspicuously pale, does not become larger or darker in winter.

In posteriolateral view, A. nasomaculatus

in summer coat resembles Oryx leucoryx in that its conspicuousness is mainly owing to the overall pallor of the whole figure, and
in winter coat has a pattern of conspicuously pale hindquarters, abdomen, and legs (https://www.barhbarhunting.com/addax-antelope).

Summer coat:

https://news.mongabay.com/2016/05/three-saharan-addax-antelope-left-wild/

https://www.pinterest.com.au/pin/714876140821949934/

https://jaredstabach.com/2020/02/06/reintroducing-one-of-the-rarest-antelopes-on-earth/

https://www.shutterstock.com/image-photo/addax-deer-zoo-1154750920

Winter coat:

https://gvzoo.com/animals/addax

https://www.shutterstock.com/image-photo/addax-known-screwhorn-antelope-latin-name-1657528048

Seasonally intermediate:

https://www.alamy.com/addax-addax-nasomaculatus-critically-endangered-desert-antelope-extinct-in-the-wild-in-israel-photographed-at-the-yotvata-hai-bar-nature-reserve-b-image372006043.html?imageid=90CA9E45-36C6-45DE-B13E-27CAEEB1EB34&p=211984&pn=2&searchId=506c438e00227f80acf51b2d257bfbf8&searchtype=0

https://www.shutterstock.com/image-photo/addax-white-antelope-close-portrait-1205280034

https://www.shutterstock.com/image-photo/antelope-addax-nasomaculatus-were-introduced-sahara-782427706 and https://www.shutterstock.com/image-photo/antelope-addax-nasomaculatus-were-introduced-sahara-782607367 and https://www.shutterstock.com/image-photo/antelope-addax-nasomaculatus-were-introduced-sahara-782611564 and https://www.shutterstock.com/image-photo/antelope-addax-nasomaculatus-were-introduced-sahara-782593180