milewski 的日誌

@errol-d

At first glance, the most remarkable aspect of the colouration of the blesbok/bontebok (Damaliscus pygargus) is the whitish rostrum, which constitutes a facial bleeze.

The bold, pale feature on the face of this species is extreme among all of the ungulates. This is because

• in the blesbok, it is the most conspicuous feature on the whole figure (https://www.inaturalist.org/observations/130975314), and
• in the bontebok, the white on the face is only one of several large-scale, conspicuously pale features, but it is exceptionally stark and crisply-defined (https://www.warwicktarboton.co.za/other%20crea%20pgs/332BntBk.html).

However, on closer scrutiny, what may be more remarkable is that D. pygargus features three different patterns of colouration within each individual - following each other from birth to adulthood.

Another way of putting this is that infants, juveniles, and adults of D. pygargus have such different colouration that they are like three different species in one.

The main aim of this Post is to illustrate this 'triplex' colouration by means of a few, carefully selected photos.

CRYPTIC COLOURATION

Within D. pygargus, something approaching a classic example of cryptic colouration occurs: plain fawn with countershading.

This occurs from birth to three months old, after which it changes abruptly. Thus, the 'infantile' colouration lasts until weaning begins.

The cryptic 'infantile' pattern makes little sense adaptively, because there is no rationale for inconspicuousness in this species, even in infants.

Blesbok infants https://www.robertharding.com/preview/741-3687/blesbok-damaliscus-dorcas-kariega-game-reserve-south-africa/ and https://www.zooborns.com/zooborns/2018/08/meet-betty-bantu-belfasts-blesbok-calf.html

Bontebok infants https://www.shutterstock.com/it/image-photo/cute-baby-bontebok-antelope-calf-looks-744728965

DARK FACE CONTRASTING WITH PALE CHEEKS

For the next three months, when the freshly-weaned juveniles weigh about half as much as their mothers, the pattern on the face differs from those of both infants and adults. This facial pattern is

• more complex than in either infants or adults, and
• not intermediate between that of infants and that of adults (https://twitter.com/VelizarSim/status/1457031473689677833 and https://stock.adobe.com/search/images?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=0&filters%5Bcontent_type%3Atemplate%5D=0&filters%5Bcontent_type%3A3d%5D=0&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=blesbok&order=relevance&price%5B%24%5D=1&safe_search=1&search_page=2&get_facets=0&search_type=pagination&asset_id=200580481).

Supporting the interpretation that this constitutes a frontal display is the fact that the upper forelegs darken, precocially, at this stage.

The frontally conspicuous juvenile makes little sense adaptively, because there is no rationale for adults and accompanying juveniles achieving frontal conspicuousness' in different ways.

Blesbok juveniles https://www.alamy.com/juvenile-blesbok-damaliscus-pygargus-phillipsi-mountain-zebra-national-image65490812.html?imageid=E925F6B0-7DB8-4381-90A4-A1DB36C2A783&p=94604&pn=1&searchId=34a5985d254a7cecee5d7188055b6b4c&searchtype=0 and https://www.alamy.com/juvenile-blesbok-damaliscus-pygargus-phillipsi-mountain-zebra-national-image65490807.html?imageid=B8EA5253-B43F-41C0-8B90-B1BD0FE8E257&p=94604&pn=1&searchId=34a5985d254a7cecee5d7188055b6b4c&searchtype=0https://www.gettyimages.no/detail/photo/blesbok-antelope-royalty-free-image/95006564?adppopup=true

Bontebok juveniles https://www.alamy.com/stock-photo-herd-of-bontebok-antelope-with-calf-23274728.html?imageid=B8F63BA8-FA72-44CE-80AC-2EF5979BF4BB&p=71732&pn=1&searchId=abde0ec3b06a08943ffb523ff66f0db0&searchtype=0

CONSPICUOUSLY PALE FACE

Gradually and with individual variation, the rostrum turns from dark to pale, and the cheeks turn from pale to dark. The pale tends to creep upwards from the nose towards the eyes.

The conspicuous colouration of adults of D. pygargus makes sense, in principle. This is because gregarious, cursorial ungulates of open environments have nowhere to hide from predators, and have much to gain from social cohesion. However...

Blesbok adult https://stock.adobe.com/search/images?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=0&filters%5Bcontent_type%3Atemplate%5D=0&filters%5Bcontent_type%3A3d%5D=0&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=blesbok&order=relevance&price%5B%24%5D=1&safe_search=1&limit=100&search_page=3&search_type=pagination&get_facets=0&asset_id=495936526 and https://www.istockphoto.com/photo/blesbok-antelope-gm144341776-4192140?phrase=pics%20of%20a%20blesbok

Bontebok adult https://www.alamy.com/bontebok-in-the-bontebok-national-park-swellendam-western-cape-south-africa-image342638387.html?imageid=5C55BBE5-4514-4B34-AEDA-ACC05175FD68&p=22337&pn=1&searchId=b907bfe35d3c66fdb917f996c60ff601&searchtype=0

DISCUSSION

The 'triplexity' of colouration in D. pygargus remains to be explained, in adaptive terms.

Also remaining unexplained, in D. pygargus, are why

• this species exceeds other members of the same genus in conspicuous colouration,
• the face is the location of particular conspicuousness,
• in adults, the bontebok greatly exceeds the blesbok in the conspicuousness of the colouration, and
• in infants and juveniles, the blesbok somewhat exceeds the bontebok in the conspicuousness of the colouration.

Also see:
https://www.inaturalist.org/journal/milewski/76599-the-mystery-of-the-adaptive-value-of-cryptic-colouration-for-the-first-three-months-of-life-in-the-bontebok#
https://www.inaturalist.org/journal/milewski/76550-a-concise-photo-guide-to-the-differences-some-previously-overlooked-between-blesbok-and-bontebok#
https://www.inaturalist.org/journal/milewski/75748-adaptive-colouration-in-the-blesbok-damaliscus-pygargus-phillipsi-part-1-adults#
https://www.inaturalist.org/journal/milewski/75995-adaptive-colouration-in-the-blesbok-damaliscus-pygargus-phillipsi-part-2-infants-juveniles-and-adolescents#
https://www.inaturalist.org/journal/milewski/76311-adaptive-colouration-in-the-bontebok-damaliscus-pygargus-pygargus-part-1-adults#
https://www.inaturalist.org/journal/milewski/76336-adaptive-colouration-in-the-bontebok-damaliscus-pygargus-pygargus-part-2-infants-juveniles-and-adolescents#

https://theworldlink.com/news/local/2-month-old-bontebok-debuts-at-zoo/article_961cedbc-bb8a-11ec-b170-673e9365c94b.html and https://www.oregonzoo.org/node/7361/media and https://www.facebook.com/watch/?v=1029640830966480 and last few seconds of https://www.pond5.com/stock-footage/item/65434541-springbok-impala-wildebeest-and-blesbok

@tonyrebelo @jeremygilmore

I have recently described the colouration of the bontebok (https://www.inaturalist.org/journal/milewski/76311-adaptive-colouration-in-the-bontebok-damaliscus-pygargus-pygargus-part-1-adults# and https://www.inaturalist.org/journal/milewski/76336-adaptive-colouration-in-the-bontebok-damaliscus-pygargus-pygargus-part-2-infants-juveniles-and-adolescents#).

However, my use of the term 'infant' is, in a way, misleading.

This is because the 'infantile' colouration in Damaliscus pygargus actually persists over a trebling of body mass after birth.

The back of neonates only reaches the height of the maternal udder:

https://www.thetablemountainfund.org.za/species-in-focus-the-bontebok/

After three months of growth, the back of 'infants' (really juveniles that have retained infantile colouration as the tips of the horns appear) reaches the height of the maternal anus:

https://www.dreamstime.com/stock-photo-bontebok-calf-mother-her-foraging-fynbos-southern-africa-image92743101

This means that the latter are really 'juveniles dressed as infants'.

An important point about adaptive colouration in the bontebok thus emerges:

The ostensibly cryptic 'infantile' colouration, which is countershaded plain fawn (https://en.wikipedia.org/wiki/Crypsis#:~:text=Many%20animals%20have%20evolved%20so,animal%20itself%20(disruptive%20coloration), cannot actually function cryptically.

This is because

• infants do not hide even in the first few weeks of life, and
• their accompaniment of the group means that the cryptic potential of their colouration is subverted by the conspicuousness of the adults near them.

Among ruminants, the bontebok is extreme in the dichotomy between the infantile and adult patterns of colouration. These patterns are so different that the only elements in common are:

• whitish on the ventral surface of the thorax, and on the inner surfaces of the upper hindlegs,
• whitish on the ulnar surface, on the posterior of the upper foreleg,
• whitish on the anterior surfaces of the ear pinnae,
• a small white triangle just above the rhinarium,
• a demarcation in tone on the side of the rostrum, and
• darkness at the tip of the tail (the tassel being merely incipient at birth).

These elements are functionally trivial, and cannot outweigh the categorical difference in pattern.

The infantile colouration of the bontebok resembles that of adults of a thoroughly inconspicuous ruminant, the bohor reedbuck (https://www.inaturalist.org/taxa/42304-Redunca-redunca).

Were it the case that infants hide for several weeks, and that the infantile colouration is lost at several weeks old, then the infantile colouration of the bontebok could be interpreted as adaptive. However, such is not the case.

So, how has the evolutionary process resulted in the infantile colouration of the bontebok?

This adds to at least two other unsolved questions about the colouration of the bontebok, viz.

• how is it adaptive for the bontebok to be so much more conspicuous than other species of Damaliscus - including the blesbok, which ostensibly belongs to the same species?
• how is it adaptive for the white ventral panel to be configured in such a way that it reveals heavy pregnancy to potential predators, thus accentuating a vulnerability?

The following show how conspicuous pregnancy is in the bontebok, owing to the distension of the pale ventral panel:

https://www.inaturalist.org/observations/97905171

https://www.alamy.com/bontebok-female-with-young-de-hoop-nature-reserve-western-cape-south-africa-africa-damaliscus-dorcas-dorcas-image228117439.html?imageid=373F25EB-E0E9-443A-8DD5-4194A60EEA24&p=205512&pn=1&searchId=b907bfe35d3c66fdb917f996c60ff601&searchtype=0

https://www.bbc.com/news/science-environment-52881831

https://www.dreamstime.com/stock-photo-bontebok-wide-open-field-medium-sized-generally-dark-brown-antelope-prominent-white-blaze-image77512544

https://www.dreamstime.com/stock-photo-bontebok-field-looking-perfect-medium-sized-generally-dark-brown-antelope-prominent-wide-white-image77512668

https://depositphotos.com/598312898/stock-photo-bontebok-damaliscus-pygargus-bushmans-kloof.html

https://www.mediastorehouse.com/ardea-wildlife-pets-environment/animals/mammals-bovidae-bontebok/bonteboks-fynbos-13230782.html

https://www.inaturalist.org/observations/68890585

scroll to 12th photo in https://puppy1952.wordpress.com/category/the-overberg/

https://www.flickr.com/photos/christiansanchez/15277125719

@geichhorn @michalsloviak @tonyrebelo @jeremygilmore @tandala @colin25 @paradoxornithidae @simontonge @henrydelange @jwidness @chewitt1 @douglasriverside @matthewinabinett @bobby23 @bluehillescape

I have recently scrutinised all of the thousands of photos, on the Web, of Damaliscus pygargus (https://www.inaturalist.org/taxa/42275-Damaliscus-pygargus).

The following are my findings, w.r.t. the differences in appearance between the two subspecies.

In all cases, I show the blesbok (Damaliscus pygargus philipsi) first, and the bontebok (Damaliscus pygargus pygargus) second.

Please note that sexual dimorphism is greater in the blesbok than in the bontebok.

MALE BODY FORM STOUTER IN BLESBOK

Blesbok https://es.123rf.com/photo_27663869_a-blesbok-antelope-damaliscus-pygargus-standing-in-grassland-south-africa.html
Bontebok https://www.krugerpark.co.za/africa_bontebok.html

HORNS LONGER IN BLESBOK

Female:

Blesbok https://www.dreamstime.com/royalty-free-stock-photos-blesbok-antelope-image3045098
Blesbok https://www.agefotostock.com/age/en/details-photo/blessbock-damaliscus-pygargus-phillipsi-suedafrika-afrika-gruppe-blesbok-damaliscus-pygargus-phillipsi-south-africa-group/ZON-2448458/1
Bontebok https://www.alamy.com/bontebok-female-with-young-de-hoop-nature-reserve-western-cape-south-africa-africa-damaliscus-dorcas-dorcas-image228117439.html?imageid=373F25EB-E0E9-443A-8DD5-4194A60EEA24&p=205512&pn=1&searchId=e1c83791dbb28b2649d55bb669e0fbda&searchtype=0

Male:

Blesbok https://www.agefotostock.com/age/en/details-photo/blesbok-damaliscus-pygargus-phillipsi-adult-in-open-grassland-feeding-on-dry-grass-mountain-zebra-national-park-eastern-cape-south-africa-africa/ZI6-3207749/1
Bontebok https://www.alamy.com/bontebok-damaliscus-pygargus-damaliscus-dorcas-damaliscus-dorcas-dorcas-on-grassland-south-africa-bredasdorp-de-hoop-nature-reserve-image255390786.html

MALE HORNS PALER IN BLESBOK

Blesbok https://www.agefotostock.com/age/en/details-photo/blesbok-damaliscus-pygargus-phillipsi-mountain-zebra-national-park-south-africa-africa/RHA-764-3210/1
Bontebok https://www.gettyimages.com.au/detail/photo/bontebok-damaliscus-dorcas-at-bontebok-national-royalty-free-image/523049311?phrase=bontebok&adppopup=true

TAIL:
PALE STALK LONGER IN BONTEBOK
TASSEL PALER AND LONGER IN BLESBOK

Blesbok https://www.alamy.com/blesbok-damaliscus-pygargus-phillipsi-an-antelope-endemic-to-south-africa-and-swaziland-grazing-in-grassland-image344938371.html
Blesbok https://www.gettyimages.no/detail/photo/blesbok-antelopes-in-heat-royalty-free-image/547464562?adppopup=true
Bontebok https://www.dreamstime.com/stock-image-bontebok-antelope-image14126791

BACK-OF-EAR SHEENIER IN BLESBOK

Blesbok https://www.agefotostock.com/age/en/details-photo/blesboks-damaliscus-pygargus-phillipsi-two-adults-standing-in-open-grassland-alert-mountain-zebra-national-park-eastern-cape-south-africa-africa/ZI6-3207754/1
Bontebok https://www.inaturalist.org/observations/71049460

LOWER LEGS CLEARER IN BONTEBOK

Blesbok https://upload.wikimedia.org/wikipedia/commons/3/3a/Damaliscus_pygargus_phillipsi.jpg
Bontebok https://www.alamy.com/stock-photo-bontebok-antelope-17066360.html?imageid=AFA96455-2E25-41C8-91B0-1B7B94A1EA3C&p=4877&pn=1&searchId=abde0ec3b06a08943ffb523ff66f0db0&searchtype=0

RUMP CLEARER IN BONTEBOK

Blesbok https://www.istockphoto.com/photo/beautiful-blesbok-antelope-with-a-white-face-standing-in-the-green-field-gm1455330187-490697231?phrase=pics%20of%20a%20blesbok
Bontebok https://www.inaturalist.org/observations/57714646

PALE FACE MORE EXPANSIVE IN BLESBOK

Blesbok https://www.shutterstock.com/it/image-photo/antelope-wild-blesbok-blesbuck-lying-down-2223739223
Blesbok https://www.inaturalist.org/observations/70027286
Bontebok 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=damaliscus&order=relevance&safe_search=1&limit=100&search_page=10&search_type=pagination&get_facets=0&asset_id=271748733

TORSO:
VENTRAL PALE MORE EXTENSIVE IN BONTEBOK
BACK MORE CONTRASTING WITH FLANKS IN BONTEBOK

Blesbok https://www.agefotostock.com/age/en/details-photo/bontebok-blesbok-damaliscus-dorcas-stands-in-african-savanna-south-africa-eastern-cape-mountain-zebra-national-park/BWI-BS420963
Bontebok https://www.gettyimages.com.au/detail/photo/bontebok-damaliscus-dorcas-endemic-species-of-royalty-free-image/139810109?phrase=bontebok&adppopup=true

BACK-OF-FORELEG MORE DISTINCT IN BLESBOK

Blesbok https://stock.adobe.com/search/images?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=0&filters%5Bcontent_type%3Atemplate%5D=0&filters%5Bcontent_type%3A3d%5D=0&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=blesbok&order=relevance&price%5B%24%5D=1&safe_search=1&limit=100&search_page=3&search_type=pagination&get_facets=0&asset_id=514194342
Bontebok https://www.gettyimages.com.au/detail/photo/bontebok-side-view-royalty-free-image/200214468-001?phrase=bontebok&adppopup=true
Bontebok https://www.gettyimages.com.au/detail/photo/bontebok-bushmans-kloof-private-game-reserve-royalty-free-image/925965224?phrase=bontebok&adppopup=true

INFANTS PALER IN BLESBOK

Blesbok https://www.shutterstock.com/it/image-photo/blesbok-mother-small-calf-leaning-against-91405400
Blesbok https://stock.adobe.com/search/images?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=0&filters%5Bcontent_type%3Atemplate%5D=0&filters%5Bcontent_type%3A3d%5D=0&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=blesbok&order=relevance&price%5B%24%5D=1&safe_search=1&limit=100&search_page=3&search_type=pagination&get_facets=0&asset_id=410239969
Bontebok https://www.inaturalist.org/photos/40826355
Bontebok https://www.dreamstime.com/royalty-free-stock-image-mother-calf-blesbok-antelope-image21744916
Bontebok https://www.mediastorehouse.com.au/ardea-wildlife-pets-environment/danita-delimont/bontebok-rare-antelope-bushmans-25400655.html

INFANTILE FACIAL MARKINGS CLEARER IN BONTEBOK

Blesbok https://www.shutterstock.com/it/image-photo/blesbuck-newborn-baby-89983321
Blesbok https://stock.adobe.com/search/images?k=blesbok&asset_id=544432933
Bontebok https://www.shutterstock.com/it/image-photo/bontebok-calf-national-park-swellendam-western-2090432353
Bontebok https://www.inaturalist.org/observations/137997739
Bontebok https://upload.wikimedia.org/wikipedia/commons/e/e4/Bontebok_%28Damaliscus_pygargus_pygargus%29_young_..._%2832834333045%29.jpg
Bontebok https://www.flickr.com/photos/berniedup/50179826247

JUVENILE FACE DARKER IN BLESBOK

Blesbok https://www.agefotostock.com/age/en/details-photo/juvenile-blesbok-damaliscus-pygargus-phillipsi-mountain-zebra-national-park-south-africa-africa/RHA-764-4222/1
Blesbok https://www.agefotostock.com/age/en/details-photo/juvenile-blesbok-damaliscus-pygargus-phillipsi-mountain-zebra-national-park-south-africa-africa/RHA-764-4226/1
Bontebok https://www.gettyimages.com.au/detail/photo/bontebok-damaliscus-dorcas-at-bontebok-national-royalty-free-image/523049313?phrase=bontebok&adppopup=true

PALE SPOT ON FOREHEAD APPEARS AT >1 YEAR IN BLESBOK, VS 4 MONTHS IN BONTEBOK

Blesbok https://www.inaturalist.org/observations/21633759
Blesbok https://www.istockphoto.com/photo/young-blesbok-gm947259792-258650817
Blesbok https://www.agefotostock.com/age/en/details-photo/blesbok-damaliscus-pygargus-phillipsi-young-walking-in-open-grassland-alert-mountain-zebra-national-park-eastern-cape-south-africa-africa/ZI6-3207756
Bontebok https://es.123rf.com/photo_10162424_bontebok-damaliscus-dorcas-at-bontebok-national-park-in-south-africa.html
Bontebok https://www.shutterstock.com/it/image-photo/bontebok-antelope-calf-national-park-south-124597081
Bontebok https://www.shutterstock.com/it/image-photo/bontebok-antelope-female-calf-national-park-124597063

DISCUSSION

I have not featured the usual distinction, viz. that of a separation between the pale rostrum and the pale patch on the forehead (https://www.dreamstime.com/stock-image-blesbok-buck-head-image29082851).

This is because it has been overrated, given the individual variation and a tendency for coalescence with age in the blesbok.

Of the distinctions I have featured above, a few are well-known, but most have been previously underplayed - or completely overlooked.

Features which seem never to have been previously mentioned in the literature are those involving

• the ears, tail-tassel, and expansion of pale on the face, and
• the facial colouration of infants and juveniles.

Regarding the ears and tail-tassel, the previous oversight is understandable, because a particular search-image is needed. However, regarding expansion of pale on the face, the previous oversight is surprising. This is because dozens of photos of the blesbok on the Web, particularly from zoological gardens, show the phenomenon clearly.

The distinctions between the blesbok and the bontebok at the infantile and juvenile stages deserve further scrutiny, beyond the limited photographic evidence.

This is partly because ontogenetic differences - as well as those of sexual dimorphism - are likely to be particularly revealing, taxonomically.

Given this comprehensive list of phenological clues, it remains possible that the blesbok and the bontebok are different species, not merely subspecies.

@tonyrebelo @jeremygilmore @ludwig_muller @botswanabugs @oviscanadensis_connerties @tandala @capracornelius @michalsloviak @henrydelange @ray_turnbull @bit @matthewinabinett @fdoucet @felix_riegel @jaunnemarelize @dbeadle @paradoxornithidae @geichhorn @alexiadievart @coyotehog2 @lswift @stanvrem @cheekychew @jandutoit @bobby23 @jwidness @gigilaidler @simontonge @markheystek @bluehillescape

...continued from https://www.inaturalist.org/journal/milewski/76311-adaptive-colouration-in-the-bontebok-damaliscus-pygargus-pygargus-part-1-adults#

The bontebok is well-known for its extreme colouration. However, what is not generally appreciated is how complex the facial colouration is, as it develops from birth to adulthood.

This complexity has never, as far as I know, been described, let alone explained.

At birth, the colouration of the bontebok is fairly plain (https://www.alamy.com/bontebok-damaliscus-pygargus-dorcas-three-ewes-with-their-calves-dehoop-nature-reserve-western-cape-south-africa-september-image262940011.html?imageid=37BEF09A-E8CD-4363-BA0C-D7A889A5A0DE&p=215617&pn=4&searchId=dca6a568865628209af3d56514ac1f36&searchtype=0).

This is puzzling, given that infants do not hide in this species, instead accompanying their mothers from the start.

However, the puzzle of plain colouration in infancy is eclipsed by a greater puzzle as the animal grows into the juvenile stage.

This is because the facial pattern goes through a series of changes that seem superfluous to the relatively simple conversion of the fawn-coloured rostrum of infants to the white rostrum of adults.

It is almost as if Nature has used the juvenile face of the bontebok as a canvas, on which to paint - merely for their own sake - a series of organised designs, before erasing them (https://www.shutterstock.com/it/image-photo/bontebok-antelope-calf-national-park-south-124626181 and https://www.shutterstock.com/it/image-photo/young-bontebok-waiting-cross-road-national-1012848241 and https://pixels.com/featured/bontebok-tony-camachoscience-photo-library.html).

INFANTS

At birth, the bontebok is fawn-coloured with countershading, plus

• a trace of the ulnar pattern (see the posterior surface of the upper foreleg in https://www.alamy.com/stock-photo-young-bontebok-damaliscus-pygargus-dorcas-in-postberg-west-coast-national-26607506.html?imageid=A6BE5E5E-5F5F-4685-894F-CFAC80895E31&p=18540&pn=3&searchId=6d8a7f95c3b92935b5e8c1d5d07d00ff&searchtype=0),
• an incipient dark tip to the tail, and
• a subtle, but consistent and crisply-defined, pattern on the head.

The pattern on the head may seem negligible at first glance. However, on closer examination it poses a fundamental evolutionary puzzle.

I describe this pattern as follows:

• the rostrum and forehead are fawn-coloured, with a crisp demarcation on the side of the rostrum (https://www.shutterstock.com/it/image-photo/bontebok-calf-national-park-swellendam-western-2090432353),
• the orbits are white, extending towards the corner of the mouth (https://www.inaturalist.org/observations/137997739),
• the upper lips are fawn-coloured, but there is a small triangle of whitish pelage just above the rhinarium (https://en.wikipedia.org/wiki/Rhinarium),
• the cheeks are a pale tone of fawn, grading to whitish medially (https://upload.wikimedia.org/wikipedia/commons/e/e4/Bontebok_%28Damaliscus_pygargus_pygargus%29_young_..._%2832834333045%29.jpg),
• the ventral surface of the mandibles are white, extending to the area between the gape of the mouth and the cheeks (https://www.flickr.com/photos/berniedup/50179826247),
• the base of the ear is whitish, and
• the posterior surface of the ear pinnae is simply fawn-coloured, like most of the animal (https://www.inaturalist.org/observations/83966791).

The facial pattern of infants of the bontebok is inconspicuous, because

• the pale feature on and near the orbits is small-scale, and
• there is no dark pelage, anywhere on the head.

However, what is remarkable is that this pattern is not merely a nebulous or incipient version of the adult colouration, as is the case in hippotragin bovids (https://www.inaturalist.org/journal/milewski/76424-which-ruminant-is-born-with-the-most-conspicuous-facial-pattern-of-colouration-part-1-hippotragin-and-alcelaphin-bovids#).

Instead, the pattern is different from that in adults. It is as if infants and adults are different species.

To be precise, the only parts of the head of infants that already show adult colouration are:

• a small whitish triangle just above the rhinarium, and
• the whitish hairs on the anterior surface of the ear pinnae.

The following show infants close-up:

https://www.inaturalist.org/observations/63400386

https://www.inaturalist.org/observations/115686906

https://www.inaturalist.org/observations/99722303

The following show infants with their mothers:

https://www.dreamstime.com/royalty-free-stock-image-mother-calf-blesbok-antelope-image21744916

https://www.dreamstime.com/stock-photo-bontebok-calf-mother-her-foraging-fynbos-southern-africa-image92719587

https://pixels.com/featured/bontebok-mother-and-calf-peter-chadwickscience-photo-library.html

https://www.dreamstime.com/young-bontebok-adult-fynbos-fawn-coloured-young-bontebok-fynbos-veld-adult-near-cape-point-western-cape-image268185782

https://www.alamy.com/bontebok-damaliscus-pygragus-dorcas-ewe-with-one-day-old-calf-dehoop-nature-reserve-western-cape-south-africa-september-image262940010.html

https://www.alamy.com/stock-photo-bontebok-with-calf-damaliscus-pygargus-pygarus-de-hoop-nature-reserve-59178437.html?imageid=03857B0D-5BE3-4A6C-B22B-16A28380CD06&p=22059&pn=5&searchId=a4908a5258dd3ea4c025bcd202432b49&searchtype=0

https://www.alamy.com/bontebok-damaliscus-pygargus-pygargus-adult-and-calf-sitting-de-hoop-south-africa-december-image263070029.html?imageid=88C59DAE-1AFE-4E31-9DD7-E9102086EA36&p=215536&pn=1&searchId=25869b8bb63848eab5bc67f94e53a679&searchtype=0.

The infantile pattern of colouration persists to the age of three months. At this stage the horn-tips have appeared, and the body mass exceeds a quarter of maternal body mass:

https://www.dreamstime.com/stock-photo-bontebok-calf-mother-her-foraging-fynbos-southern-africa-image92743101

https://www.alamy.com/bontebok-with-young-image1218482.html?imageid=B2DF1491-9EBB-4DA5-8DC2-552475BDDC6F&p=4877&pn=4&searchId=29c543d132619cf1217ce0a23a3945c6&searchtype=0

https://www.alamy.com/bontebok-with-two-youngsters-image1218481.html?imageid=9C191390-7AA0-43F4-9B4F-5038BD5BE66A&p=4877&pn=5&searchId=78e3c36a9917c21e07efdd82f4c4fbc0&searchtype=0

The following series of photos, of an individual infant (1-2 months old), is one of the clearest expositions on the Web of the infantile colouration of the bontebok. The infantile colouration of the bontebok is not as pale as that of the blesbok, but more clearly shows countershading.

Damaliscus pygargus pygargus:

https://www.shutterstock.com/it/image-photo/baby-bontebok-antelope-calf-looks-curiously-744728989

https://www.shutterstock.com/it/image-photo/cute-baby-bontebok-antelope-calf-looks-744728965

https://www.shutterstock.com/it/image-photo/baby-bontebok-antelope-calf-stays-close-744728971

https://www.shutterstock.com/it/image-photo/cute-baby-bontebok-antelope-calf-scratches-744728980

https://www.shutterstock.com/it/image-photo/cute-baby-bontebok-antelope-calf-scratches-744728986

https://www.shutterstock.com/it/image-photo/baby-bontebok-antelope-calf-looks-see-744728992

https://www.shutterstock.com/it/image-photo/two-cute-baby-bontebok-antelope-calves-744728956

JUVENILES

The following series provides one of the clearest illustrations of juvenile colouration in the bontebok:
https://www.shutterstock.com/it/image-photo/bontebok-damaliscus-pygargus-pygarus-south-africa-560325085 and https://www.shutterstock.com/it/image-photo/bontebok-damaliscus-pygargus-pygarus-south-africa-560325091 and https://www.shutterstock.com/it/image-photo/bontebok-damaliscus-pygargus-pygarus-south-africa-560325112.

At the juvenile stage, the colouration on the neck, body, and legs changes directly towards that of the adult.

However, the colouration of the head goes through convoluted changes.

The first change on the head is a darkening of the rostrum (https://www.alamy.com/m2-304d-yearling-bontebok-head-image6516263.html?imageid=6FB7B5E5-32AD-4555-AD1C-BE8C66B0C857&p=1787&pn=6&searchId=d7a105eea18d32dc6155ddf3de390174&searchtype=0).

The following (https://www.shutterstock.com/it/image-photo/bontebok-antelope-calf-national-park-south-124597081 and https://www.shutterstock.com/it/image-photo/bontebok-antelope-calf-earlymorning-light-125978060 and https://www.shutterstock.com/it/image-photo/bontebok-antelope-calf-de-hoop-nature-126157526 and https://www.shutterstock.com/it/image-photo/bontebok-antelope-mother-calf-national-park-124597057 and https://www.dreamstime.com/bontebok-damaliscus-pygargus-jonge-young-image129038812) show that there is a brief stage at which the darkest part of the juvenile figure (apart from the developing tail-tassel) is a particular panel on the front of the face.

This is closely followed by a darkening of the orbits, and the appearance of a complex, pale streak from the cheek, through the temple, to the crown (third photo in https://www.inaturalist.org/observations/121214288 and https://www.shutterstock.com/it/image-photo/bontebok-damaliscus-pygargus-pygarus-south-africa-560325085 and https://animals.sandiegozoo.org/animals/bontebok).

The following shows the dark/pale differentiation on the cheek (https://www.shutterstock.com/it/image-photo/bontebok-antelope-calf-national-park-south-124626181).

The following shows the maximum extent of pale on and near the temples (https://www.shutterstock.com/it/image-photo/baby-bontebok-looking-right-mediumsized-generally-485672296).

The pale on the temples is among the last signs of the juvenile colouration to disappear (https://www.inaturalist.org/observations/137506000).

The whitish ventral surface of the mandibles remains in the juvenile stage (https://www.shutterstock.com/it/image-photo/young-playful-antelope-1327148681). The following shows the discrete pattern that arises at 0.5-1 year old, only to vanish in adulthood (https://www.dreamstime.com/wild-african-animals-bontebok-one-rarest-antelope-world-beautiful-grassland-etosha-national-park-namibia-image183764936).

The following show juveniles probably about 6 months old:

https://www.gettyimages.com.au/detail/photo/bontebok-damaliscus-dorcas-at-bontebok-national-royalty-free-image/523049313?phrase=bontebok&adppopup=true

https://www.inaturalist.org/observations/10843075

https://www.dreamstime.com/stock-images-bontebok-damaliscus-dorcas-image20906614

https://www.alamy.com/stock-photo-herd-of-bontebok-antelope-with-calf-23274728.html?imageid=B8F63BA8-FA72-44CE-80AC-2EF5979BF4BB&p=71732&pn=1&searchId=abde0ec3b06a08943ffb523ff66f0db0&searchtype=0

https://www.inaturalist.org/observations/104575032

The following show juveniles about one year old, when the dark on the rostrum is being gradually replaced by the white hairs of adulthood:

https://pixels.com/featured/bontebok-tony-camachoscience-photo-library.html

https://www.inaturalist.org/observations/16478604

https://www.alamy.com/a-vertical-shot-of-bontebok-standing-on-grassland-in-a-park-image499977486.html?imageid=A3EA59CE-7513-4A04-94CC-492D2B267CD8&p=829514&pn=9&searchId=357b330dca08dc7955106e41cd143444&searchtype=0

https://www.alamy.com/extreme-close-up-of-the-head-and-neck-of-a-wild-beautiful-bontebok-antelope-looking-at-the-camera-in-the-wilderness-of-south-africa-shot-on-safari-image435705572.html?imageid=382F9E4B-C34E-4EDB-BCCA-399C10C04B3A&p=576257&pn=1&searchId=abde0ec3b06a08943ffb523ff66f0db0&searchtype=0

The following (https://www.inaturalist.org/observations/52622577 and https://www.alamy.com/stock-photo-i-see-you-bontebok-the-bontebok-is-a-medium-sized-generally-dark-brown-119828808.html?imageid=262BD3B2-8140-4150-8B1D-BB20F2C8C369&p=260684&pn=4&searchId=29c543d132619cf1217ce0a23a3945c6&searchtype=0 and https://www.dreamstime.com/young-bontebok-grazing-young-bontebok-grazing-cape-point-national-park-cape-town-south-africa-image245392763 and https://www.dreamstime.com/stock-photo-baby-bontebok-medium-sized-generally-dark-brown-antelope-prominent-wide-white-blaze-its-face-image77372211) show particularly clearly the tardiness of the posterior surface of the upper foreleg, above the carpal, in turning dark.

Throughout the juvenile stage, the ventral surface of the neck retains the countershading that will eventually be lost in adulthood (https://www.inaturalist.org/observations/131702545).

The following, of juveniles more than one year old (https://www.alamy.com/bontebok-female-with-young-de-hoop-nature-reserve-western-cape-south-africa-africa-damaliscus-dorcas-dorcas-image228117439.html?imageid=373F25EB-E0E9-443A-8DD5-4194A60EEA24&p=205512&pn=1&searchId=abde0ec3b06a08943ffb523ff66f0db0&searchtype=0 and https://www.alamy.com/bontebok-female-and-juvenile-de-hoop-national-park-western-cape-south-africa-damaliscus-dorcas-dorcas-image414952533.html?imageid=304942E1-F18D-4D68-AE40-F31399C02086&p=1420153&pn=4&searchId=29c543d132619cf1217ce0a23a3945c6&searchtype=0), show several aspects particularly clearly, viz.

• the horns are about three-quarters of full length and the body mass is about 60% of maternal body mass,
• the dark pelage on the figure remains paler than that of adult females,
• the face remains proportionately shorter than in adults, limiting the prominence of the whitish (which is not yet fully white) on the face, and
• the dark pelage on the legs remains incomplete.

When the horns reach three-quarters of their full length (https://www.shutterstock.com/it/image-photo/yes-cute-bontebok-mediumsized-generally-dark-484356040 and https://www.shutterstock.com/it/image-photo/baby-bontebok-497894932), the few juvenile features remaining include

• a trace of countershading on the ventral surface of the neck,
• incompleteness of the dark above the carpal, and
• a pale streak on the temple.

ADOLESCENTS

One of the last features to form completely is the dark pelage on the posterior surface of the upper foreleg, just below the white patch on the ulna (https://www.dreamstime.com/stock-photo-bontebok-perfect-pose-medium-sized-generally-dark-brown-antelope-prominent-wide-white-blaze-its-image77512322 and https://www.inaturalist.org/observations/146638259).

As the rostrum rapidly lengthens and the facial colouration approaches completeness, a dark periphery to the pale features on the forehead and rostrum can intensify and linger (https://www.istockphoto.com/photo/bontebok-antelope-gm136712138-18853032?phrase=pics%20of%20a%20blesbok and https://www.alamy.com/stock-photo-portrait-of-an-endangered-bontebok-antelope-damaliscus-pygargus-dorcas-22757989.html?imageid=D0FE2C16-1433-4C7A-9D18-B2AC8938DBEE&p=70019&pn=1&searchId=abde0ec3b06a08943ffb523ff66f0db0&searchtype=0).

The colouration becomes complete before the horns have attained their full length (https://www.dreamstime.com/stock-image-bontebok-antelope-handsome-large-eyes-grass-mouth-image34760281). However, a trace can remain of the last juvenile feature to disappear, namely the pale vertical streak on the temples, even when the horns seem full-length.

DISCUSSION

The complexity of the changes in facial colouration can be contrasted with the simplicity of the changes on the hindquarters (https://www.alamy.com/bontebok-damaliscus-dorcas-adult-and-juvenile-in-a-flower-meadow-south-image8795878.html?imageid=BEFC3720-6ABE-438B-9767-B86189806239&p=33533&pn=11&searchId=909e0db787de943a5f89073993791964&searchtype=0 and https://www.inaturalist.org/observations/47971842).

Unlike the facial bleeze, the pygal bleeze of the bontebok starts to appear at the end of infancy (https://www.inaturalist.org/observations/10980014), and then simply and directly continues to completion within a mere three months.

The pygal bleeze is complete at about six months old (https://www.shutterstock.com/it/image-photo/young-bontebok-grazing-1349950382), when the face is still unrecognisably different from that of adults.

Almost every aspect of the ontogenetic development of colouration in the bontebok is puzzling, from the viewpoint of adaptation and evolution.

The main questions arising from this examination are as follows:

• how is it adaptive for infants to have cryptic colouration, given that they do not hide (this is particularly puzzling because the plain colouration persists despite the body mass being trebled from birth to three months old)?
• why does the facial pattern go through such complex, temporary changes from three months to one year old? and
• how has such disparity arisen between the pygal bleeze and the facial bleeze, with the former developing early and directly, vs the latter being delayed until adolescence, and emerging from an unrecognisably different, transitional pattern?

Also see https://www.inaturalist.org/journal/milewski/75995-adaptive-colouration-in-the-blesbok-damaliscus-pygargus-phillipsi-part-2-infants-juveniles-and-adolescents#.

https://www.shutterstock.com/image-photo/chamois-baby-animal-photo-408681031

https://www.alamy.com/stock-photo-isard-pyrenean-chamois-rupicapra-rupicapra-pyrenaica-juvenile-photographed-19124206.html?imageid=7E02B991-C239-4502-A4D9-88B5CA40678B&p=13619&pn=1&searchId=d5e403e46e3e5a7163d99f3864dad793&searchtype=0

https://www.alamy.com/a-cute-baby-chamois-watchs-whats-going-on-in-his-back-image234753084.html?imageid=9A56DFE1-F566-4576-BA6D-C919479A0DD1&p=688490&pn=1&searchId=d5e403e46e3e5a7163d99f3864dad793&searchtype=0

https://www.alamy.com/stock-photo-alpine-chamois-rupicapra-rupicapra-rupicapra-wildlife-animal-124419805.html?imageid=3453966A-22F5-4EBC-9C7E-AA657C08CBAF&p=227690&pn=1&searchId=d5e403e46e3e5a7163d99f3864dad793&searchtype=0

https://www.alamy.com/chamois-rupicapra-rupicapra-mother-and-young-standing-in-snow-alpes-italy-image239496480.html?imageid=D7347C62-D046-4FA2-A3FD-395EB8847140&p=295065&pn=1&searchId=d5e403e46e3e5a7163d99f3864dad793&searchtype=0

https://www.alamy.com/stock-photo-baby-chamois-walking-alone-on-the-mountain-132918192.html?imageid=EB12E758-EC11-4CD2-909D-C913F609E187&p=315952&pn=1&searchId=d5e403e46e3e5a7163d99f3864dad793&searchtype=0

https://www.alamy.com/chamois-gaemse-rupicapra-rupicapra-cute-fawn-young-baby-animal-standing-in-a-flowering-alpine-meadow-watching-for-its-parents-europe-image333942704.html?imageid=C4944BA3-64EB-454E-9DEA-6EDE8475CC2A&p=268352&pn=1&searchId=d5e403e46e3e5a7163d99f3864dad793&searchtype=0

https://www.alamy.com/stock-photo-chamois-rupicapra-rupicapra-fawn-running-down-a-grassy-acclivity-alps-47870222.html?imageid=D33203BF-CA3B-4DC1-9170-2890325D08DB&p=57875&pn=1&searchId=d5e403e46e3e5a7163d99f3864dad793&searchtype=0

https://www.alamy.com/stock-photo-baby-chamois-in-the-mercantour-national-park-france-alpes-maritimes-21392636.html?imageid=753BE8D7-B252-4972-9069-8D36A0048171&p=17887&pn=1&searchId=d5e403e46e3e5a7163d99f3864dad793&searchtype=0

https://www.alamy.com/close-up-of-baby-chamois-on-land-image265013737.html?imageid=43821891-4931-4C65-920D-4503C6BBAAD0&p=857264&pn=1&searchId=d5e403e46e3e5a7163d99f3864dad793&searchtype=0

https://www.alamy.com/stock-photo-chamois-rupicapra-rupicapra-fawn-standing-amongst-pine-switzerland-47936822.html?imageid=92C97D23-DCC2-48DD-88D3-1A4FF3976531&p=34210&pn=1&searchId=d5e403e46e3e5a7163d99f3864dad793&searchtype=0

https://www.alamy.com/chamois-fawn-image485028099.html?imageid=3305DD28-607D-4C77-B855-A5E8C2D7E268&p=1950458&pn=1&searchId=d5e403e46e3e5a7163d99f3864dad793&searchtype=0

https://www.alamy.com/stock-photo-baby-chamois-in-nature-126686414.html?imageid=5AAF8083-2FB8-47FB-877B-764DAB2A92BE&p=163514&pn=1&searchId=d5e403e46e3e5a7163d99f3864dad793&searchtype=0

https://www.alamy.com/young-chamois-rupicapra-rupicapra-portrait-alps-france-image425594295.html?imageid=9844F3FF-32A3-4AD2-9097-E852636FA568&p=1286366&pn=1&searchId=d5e403e46e3e5a7163d99f3864dad793&searchtype=0

https://www.alamy.com/stock-photo-isard-pyrenean-chamois-rupicapra-rupicapra-pyrenaica-mother-and-baby-19124207.html?imageid=8F91496C-1BA6-400F-91F9-41F25A60927C&p=13619&pn=1&searchId=d5e403e46e3e5a7163d99f3864dad793&searchtype=0

https://www.alamy.com/chamois-chamois-goat-with-fawn-standing-in-rocky-terrain-tyrol-austria-image414951530.html?imageid=F04A7870-2BA3-49FC-9117-BFAD9A7E1C00&p=839594&pn=1&searchId=d5e403e46e3e5a7163d99f3864dad793&searchtype=0

https://www.alamy.com/stock-photo-chamois-rupicapra-rupicapra-female-with-young-grimsel-bern-switzerland-26563634.html?imageid=6C37AAF3-FA4E-4F5C-B4C1-665BC4CA41AF&p=62076&pn=1&searchId=d5e403e46e3e5a7163d99f3864dad793&searchtype=0

https://www.alamy.com/chamois-or-goat-fawn-standing-in-rocky-terrain-tyrol-austria-image414951536.html?imageid=8B3D8F38-955F-458F-A16E-1E14F5CA5A60&p=839594&pn=1&searchId=d5e403e46e3e5a7163d99f3864dad793&searchtype=0

https://www.alamy.com/two-one-year-old-chamois-in-autumn-in-karwendel-mountains-image469119866.html?imageid=D909EE9B-2BC6-422E-A4C1-8C39710E84DA&p=469663&pn=1&searchId=d5e403e46e3e5a7163d99f3864dad793&searchtype=0

@tandala @simontonge @paradoxornithidae @tonyrebelo @jeremygilmore @oviscanadensis_connerties @davidbygott @dejong @michalsloviak @christiaan_viljoen @capracornelius @gigilaidler @maxa11an

Various ruminants have bold facial markings in both sexes, helping to make the animals adaptively conspicuous.

An example is https://www.sa-venues.com/wildlife/wildlife_roan_antelope.php.

However, in most ruminants, infants hide for a period (https://www.jstor.org/stable/3061529). This makes it adaptive for the colouration to be inconspicuous at birth.

In this Post, I examine four species of bovids with boldly-marked faces, and I illustrate the colouration in infancy, relative to that in adulthood.

These are

• two hippotragins, in which infants hide, and
• two alcelaphins, in which infants accompany their mothers continually right from the start.

ORYX GAZELLA (https://www.inaturalist.org/taxa/42308-Oryx-gazella)

In this species of hippotragin bovid, adults possess a facial bleeze.

At birth, the facial pattern is not plain. However, it is so nebulous that it is certainly inconspicuous (https://upload.wikimedia.org/wikipedia/commons/0/05/Oryx_gazella_3_-_Gemsbok_cub.JPG).

As infants grow, the facial pattern, like the horns, develops precocially.

https://www.mindenpictures.com/stock-photo-gemsbok-oryx-gazella-female-with-two-calves-namibrand-reserve-namib-naturephotography-image90799302.html

https://www.zoochat.com/community/media/gemsbok-calf-whipsnade-04-jul-2014.262375/

https://www.alamy.com/gemsbok-oryx-gazella-calf-image4734981.html

https://www.alamy.com/gemsbok-oryx-gazella-calf-image4734984.html

HIPPOTRAGUS EQUINUS (https://www.inaturalist.org/taxa/42332-Hippotragus-equinus)

This hippotragin bovid probably qualifies for a facial bleeze in adults (https://www.inaturalist.org/observations/138018015).

The relationship of infants to adults is similar to that in Oryx gazella.

However, the pattern is so precocial that an argument can be made for at least a facial flag in infants. If so, H. equinus may exemplify the presence at birth of a facial flag, in ruminants.

https://www.agefotostock.com/age/en/details-photo/roan-antelope-hippotragus-equinus-calf-standing-in-dry-woodland-fatalah-reserve-senegal-january/FHR-10028-00039-849

https://es.123rf.com/photo_27725369_roan-antelope-hippotragus-equinus-calf.html

https://www.zoochat.com/community/media/roan-antelope-calf.55666/

https://www.zoochat.com/community/media/roan-antelope-calf.145764/

https://www.inaturalist.org/observations/33354786

DAMALISCUS PYGARGUS (https://www.inaturalist.org/taxa/42275-Damaliscus-pygargus)

This species of alcelaphin bovid certainly qualifies for a facial bleeze in adults.

As in the hippotragins shown above, infants are born with a trace of the facial pattern of adults. However, the relative placement of dark/pale is puzzlingly inverted (see https://www.inaturalist.org/journal/milewski/76336-adaptive-colouration-in-the-bontebok-damaliscus-pygargus-pygargus-part-2-infants-juveniles-and-adolescents# and https://www.inaturalist.org/journal/milewski/75995-adaptive-colouration-in-the-blesbok-damaliscus-pygargus-phillipsi-part-2-infants-juveniles-and-adolescents#).

https://www.zooborns.com/zooborns/2012/04/meet-blossom-the-blesbok-calf-born-at-belfast-zoo.html

https://www.dreamstime.com/stock-photos-blesbok-antelope-calf-standing-protectively-next-to-s-baby-image36296983

CONNOCHAETES ALBOJUBATUS (https://www.inaturalist.org/observations?taxon_id=525438)

Unlike the three species shown above, the facial colouration of Connochaetes albojubatus is ambivalent in its boldness. However, I include it here because it is the form of wildebeest with the most conspicuous facial colouration.

In the case of wildebeests, the patterns tend to be obfuscated by

• the confusing complex of species/subspecies, in which various aspects/features of colouration vary in emphasis rather than presence/absence,
• sheen/antisheen and other effects of illumination, and
• individual variation.

However, in adults of C. albojubatus, the cheeks tend to be clearer and paler than in other forms of wildebeest, and equally sheeny. This means that C. albojubatus is the wildebeest most likely to qualify for a facial flag.

What is noteworthy is that the facial pattern is also more preocial in C. albojubatus (https://inaturalist.ca/observations/110949669) than in other wildebeests, with the possible exception of another form with a pale beard, viz. Connochaetes mearnsi.

Adults:

The facial pattern in adults of C. albojubatus is, owing to individual variation and the effects of illumination, not consistent enough to qualify for a bleeze. Its maximum expression is seen in https://www.dreamstime.com/stock-photo-young-male-antelope-wildebeest-standing-marshy-lowland-sunn-sunny-afternoon-image89889139.

This pattern - which does qualify as a facial flag - consists of

• a consistently black rostrum,
• a pale beard, located close enough to the dark muzzle to provide pale/dark contrast, and
• cheeks that are usually pale, sheeny, and free of brindling.

https://www.alamy.com/single-wildebeest-in-amboseli-national-park-image362840009.html

https://www.alamy.com/eastern-white-bearded-wildebeest-connochaetes-taurinus-albojubatus-also-brindled-gnu-antelope-in-eastern-and-southern-africa-belongs-to-bovidae-wi-image446124408.html

https://www.alamy.com/stock-photo-eastern-white-bearded-wildebeest-connochaetes-taurinus-albojubatus-57729409.html

https://www.dreamstime.com/blue-wildebeest-wander-grasslands-tsavo-east-park-kenay-image208617369

https://www.alamy.com/blue-wildebeest-connochaetes-taurinus-males-fighting-amboseli-n-p-image443376.html

https://www.dreamstime.com/wildebeest-gnu-portrait-standing-savannah-africa-image155054207

https://inaturalist.ca/observations/5784993

https://www.alamy.com/single-blue-wildebeest-white-bearded-wildebeest-or-brindled-gnu-connochaetes-taurinus-running-across-grassland-of-the-african-savannah-kenya-image240812175.html

https://www.dreamstime.com/wildebeest-gnu-portrait-standing-savannah-africa-image155054207

https://inaturalist.ca/observations/102105372

https://www.dreamstime.com/stock-photos-three-wildebeest-run-image16846173

https://www.dreamstime.com/stock-photo-wildebeest-blue-gnu-connochaetes-taurinus-amboseli-kenya-image67014218

https://www.dreamstime.com/closeup-wildebeest-browsing-closeup-wildebeest-scientific-name-connochaetes-taurinus-nyumbu-swaheli-image-taken-image108980595

https://www.dreamstime.com/royalty-free-stock-photos-wildebeest-connochaetes-taurinus-single-mammal-ground-tanzania-image35926688

https://www.dreamstime.com/royalty-free-stock-photos-wildebeest-image7626258

https://www.alamy.com/eastern-white-bearded-wildebeest-connochaetes-taurinus-albojubatus-also-brindled-gnu-antelope-in-eastern-and-southern-africa-belongs-to-bovidae-wi-image446125271.html

https://zooinstitutes.com/animals/eastern-white-bearded-wildebeest-almaty-zoo-26267.html

https://inaturalist.ca/observations/19542826

Infants:

There are too few photos available to assess individual variation. However, the black rostrum tends to be fully expressed at birth.

The cheeks of infants are not as obviously pale as in most adults, and the pale beard (although precocial) is inconspicuous at birth.

However, a previously overlooked aspect is that, unlike adults, the blackish of the face extends ventral to the eyes (https://www.agefotostock.com/age/en/details-photo/wildebeest-calf-in-plains-amboseli-national-park-kenya/AAM-AAES71424). The facial insignia are thus, in a limited sense, better-developed in infants than in adults, making wildebeests unusual among ruminants.

It is noteworthy that Damaliscus pygargus, another alcelaphin, also has a distinction between infants and adults in the colouration of the orbits. The difference is that, in infants of D. pygargus, the orbits are noticeably pale, not noticeably dark (https://www.zooborns.com/zooborns/antelope/).

https://www.dreamstime.com/stock-photo-newborn-wildebeest-amboseli-park-kenya-mother-baby-image76472324

https://www.flickr.com/photos/sdzooglobal/9270596187

Scroll in https://movementoflife.si.edu/species/wildebeest/

https://www.gettyimages.co.uk/detail/news-photo/boston-ma-a-baby-wildebeest-born-in-the-past-week-on-news-photo/1371566822?adppopup=true

https://www.gettyimages.co.uk/detail/news-photo/boston-ma-a-baby-wildebeest-born-in-the-past-week-on-news-photo/1371566810?adppopup=true

https://www.dreamstime.com/stock-photo-newborn-wildebeest-amboseli-park-kenya-mother-baby-rest-herd-background-image76472453

Scroll in https://www.zoonewengland.org/franklin-park-zoo/our-animals/mammals/hoofed/white-bearded-wildebeest/

https://inaturalist.ca/observations/106811995

https://www.jhpostcards.com/products/white-bearded-wildebeest-riga-zoo-animals-1980-latvia-ussr-unused

Juveniles:

The facial pattern in juveniles of C. albojubatus is as conspicuous as that in adults (https://www.dreamstime.com/stock-photo-big-wildebeest-migration-african-safari-amboseli-national-park-kenia-image84361100).

As growth proceeds, the pelage below the eye loses its black pigmentation (https://inaturalist.ca/observations/6812082).

https://www.alamy.com/stock-photo-part-of-a-herd-of-blue-wildebeest-connochaetes-taurinus-grazing-126164867.html

https://www.alamy.com/herd-of-common-wildebeests-walking-in-dry-grassland-on-summer-day-in-amboseli-national-park-kenya-image502860670.html

https://www.alamy.com/blue-wildebeest-connochaetes-taurinus-amboseli-national-park-kenya-image62676645.html

https://www.alamy.com/eastern-white-bearded-wildebeest-connochaetes-taurinus-albojubatus-also-brindled-gnu-antelope-in-eastern-and-southern-africa-belongs-to-bovidae-wi-image446124965.html

https://www.alamy.com/eastern-white-bearded-wildebeest-connochaetes-taurinus-albojubatus-also-brindled-gnu-antelope-in-eastern-and-southern-africa-belongs-to-bovidae-wi-image446125038.html

https://www.alamy.com/wildebeest-in-the-national-park-tsavo-east-tsavo-west-and-amboseli-in-kenya-image483241293.html?imageid=FE32865D-C28D-4A48-A37B-54D64A5294CF&p=774865&pn=1&searchId=1ded7a829c6fd29f9a553cf0e1e2072e&searchtype=0

DISCUSSION

I know of no ruminant that is born with a facial bleeze.

A facial flag at birth seems plausible in Hippotragus equinus. This would be consistent with

• the extreme colouration of this species, in combining a bold facial pattern with plain colouration over the rest of the figure (https://www.inaturalist.org/observations/142404442), and
• the extremely large size of the ear pinnae at birth (https://es.123rf.com/photo_27725391_roan-antelope-hippotragus-equinus-calf.html).

Since infants of H. equinus hide initially, it is unknown how the precociality of the facial pattern is adaptive. Even in adults, the adaptive value of bold facial colouration in hippotragins remains poorly understood.

What is more complex, and even more intriguing, is the ontogeny of the facial pattern in certain alcelaphins.

The facial pattern in infants of wildebeests ranges from inconspicuous in Connochaetes gnou (https://www.zooborns.com/zooborns/wildebeest/ and https://www.irishnews.com/magazine/daily/2019/08/27/news/rare-baby-wildebeest-born-at-newquay-zoo-1696156/ and scroll to fifth photo in https://africafreak.com/black-wildebeest) to conspicuous in C. albojubatus.

The remaining forms are intermediate, with Connochaetes mearnsi and Connochaetes taurinus mattosi (https://www.dreamstime.com/stock-photo-blue-wildebeest-side-view-mosi-oa-tunya-nation-park-zambia-africa-image61435936) apparently exceeding Connochaetes taurinus taurinus, C. t. cooksoni, and C. t. johnstoni.

For infants of wildebeests to have conspicuous colouration seems consistent with extreme adaptation for gregariousness in open environments, and extreme precociality at birth.

However, it remains unexplained why wildebeests vary in this respect.

It remains possible that C. mearnsi (see first comment below) exceeds C. albojubatus in the consistent boldness of the facial pattern in infants. This depends on further photographic evidence.

Given that, in adults, the facial pattern in C. mearnsi is less conspicuous than that in C. albojubatus, this might make C. mearnsi unique among ruminants, in having a facial pattern more conspicuous at birth than in adulthood.

In this context, I remind readers that infants of wildebeests also possess a pedal flag (https://www.dreamstime.com/stock-photo-blue-wildebeest-connochaetes-taurinus-young-calf-playing-rain-kruger-national-park-south-africa-image60301989), absent in adults.

Also see https://www.inaturalist.org/journal/milewski/75748-adaptive-colouration-in-the-blesbok-damaliscus-pygargus-phillipsi-part-1-adults#

The bontebok (Damaliscus pygargus pygargus) is one of the most vividly-coloured wild ungulates on Earth.

However, its colouration has not previously been described coherently, relative to a conceptual framework based on adaptation. Furthermore, previous descriptions have been limited by the lack of suitable terms.

A reminder of the difference between a bleeze and a flag:

A bleeze is a large-scale feature of colouration, so bold that it makes the whole figure conspicuous even at a distance, and even when the animal is stationary.

A flag is a relatively small, or normally hidden, feature of colouration, which becomes conspicuous with motion.

The bontebok can be described as 'pied' (https://dictionary.cambridge.org/dictionary/english/pied). However, this is unsatisfactory, because

• it does not elucidate the functional organisation of the markings, and
• it does not distinguish between an adaptive design and that seen in pied individuals and breeds of domestic mammals (https://en.wikipedia.org/wiki/Piebald).

Various wild ungulates possess bleezes. However, what makes the bontebok unusual is that

• it possesses three bleezes,
• one of these, viz. the lateral bleeze, occupies the whole side of the torso from the dorsal to the ventral edge, and
• consequently, the entire adult figure can be seen as a composite bleeze, i.e. an example of thoroughly conspicuous colouration (https://www.gettyimages.com.br/detail/foto/bontebok-imagem-royalty-free/982765768?adppopup=true).

In this account, I ignore the hues on the pelage of the bontebok, and consider only the tones (white, shades of grey, and black). This is because ungulates and their carnivoran predators do not perceive hues in the same ways as humans do.

OVERALL VIEWS

https://www.shutterstock.com/it/image-photo/walking-field-bontebok-mediumsized-generally-dark-484356043

https://www.inaturalist.org/observations/11251852

https://www.dreamstime.com/bontebok-damaliscus-pygargus-image129038646

https://www.agefotostock.com/age/en/details-photo/male-blesbok-baby-portrait-malolotje-swaziland-malolotje-nature-reserve-swaziland/ALM-BP5496/1

https://www.alamy.com/stock-photo-bontebok-damaliscus-pygargus-pygarus-de-hoop-nature-reserve-western-59178463.html?imageid=04F0A152-6CA3-4A65-9067-0364F1A5F09E&p=22059&pn=4&searchId=dca6a568865628209af3d56514ac1f36&searchtype=0

https://www.alamy.com/stock-photo-a-portrait-of-a-bontebok-antelope-in-south-africa-47742290.html?imageid=53CB260B-D3BB-4DD7-B43C-33C570D2CC36&p=158473&pn=1&searchId=abde0ec3b06a08943ffb523ff66f0db0&searchtype=0

https://www.alamy.com/bontebok-damaliscus-pygargus-in-game-park-in-south-africa-looking-over-its-shoulder-image245661564.html

https://www.dreamstime.com/bontebok-damaliscus-pygargus-image129038241

FACIAL BLEEZE

The conspicuously pale patch on the rostrum of adults of Damaliscus pygargus (https://www.inaturalist.org/taxa/42275-Damaliscus-pygargus) constitutes what is probably the clearest example of a facial bleeze, in any mammal.

In the bontebok, this patch is pure white, contesting with the dark ground-colour of the face and neck.

https://www.alamy.com/stock-photo-bontebok-blesbok-damaliscus-dorcas-standing-south-africa-47895393.html?imageid=A30EE114-7C91-437B-A4EE-F0E2062F42F1&p=33610&pn=6&searchId=ab384b9287a9a62b3e65ec702d7129d5&searchtype=0

https://www.alamy.com/stock-photo-bontebok-damaliscus-dorcas-at-bontebok-national-park-in-south-africa-38098213.html?imageid=2F8F0D32-30E5-4683-816A-5422AC0E0766&p=60598&pn=2&searchId=595b2aef109e6e3945fa2d85a0f44eb0&searchtype=0

https://www.alamy.com/stock-photo-bontebok-antelope-121112217.html?imageid=C030CB48-025D-450C-9009-14F6598A42A7&p=353301&pn=1&searchId=abde0ec3b06a08943ffb523ff66f0db0&searchtype=0

https://www.gettyimages.com.au/detail/photo/bontebok-damaliscus-dorcas-at-bontebok-national-royalty-free-image/523049311?phrase=bontebok&adppopup=true

https://www.alamy.com/stock-photo-a-pair-of-bontebok-antelopes-damaliscus-pygargus-dorcas-south-africa-85437994.html?imageid=8C3973B1-D533-4CA3-B604-463AAB155B2F&p=70019&pn=1&searchId=abde0ec3b06a08943ffb523ff66f0db0&searchtype=0

There is minimal variation in the facial bleeze, between the sexes, and among individuals. However, a few individuals show slight expansion at the base of the horns (https://www.alamy.com/stock-photo-blesbok-or-bontebok-damaliscus-dorcas-dorcas-syn-damaliscus-pygargus-78567725.html?imageid=967A4632-A630-4F22-84B5-7F50172963C0&p=183822&pn=2&searchId=dff47d9894fdcd82529cde91c8758091&searchtype=0).

Comparison with blesbok (https://www.inaturalist.org/journal/milewski/75748-adaptive-colouration-in-the-blesbok-damaliscus-pygargus-phillipsi-part-1-adults#):

The pale rostral patch on the face seems proportionately slightly smaller in the bontebok than in the blesbok, owing to what I perceive to be a difference in the size of the head.

Furthermore, in the bontebok the pale on the face tends not to expand with age, as it does in the blesbok (https://www.shutterstock.com/it/image-photo/blesbok-antelope-damaliscus-pygargus-standing-grass-1329980789 and https://www.inaturalist.org/journal/milewski/75871-a-previously-overlooked-expansion-of-the-bles-in-the-blesbok-signifying-full-maturity-beyond-adulthood#).

However, the facial bleeze is as well-developed in the bontebok as in the blesbok, because it seems exempt from the glandular staining seen in males of the blesbok (https://www.alamy.com/a-blesbok-antelope-damaliscus-pygargus-south-africa-image66899227.html?imageid=AA000BC4-7506-4457-96A0-B91FB81FCF46&p=70019&pn=1&searchId=a83f931787d9571cb0a25aca9f82d745&searchtype=0 and https://www.alamy.com/stock-photo-portrait-of-a-blesbok-antelope-damaliscus-pygargus-south-africa-59076858.html?imageid=9FB1F37F-B684-4FE4-A0A4-9A9AC4C55B63&p=70019&pn=1&searchId=a83f931787d9571cb0a25aca9f82d745&searchtype=0).

LATERAL BLEEZE

The lateral bleeze of the bontebok is, proportionately, one of the largest bleezes seen in any ungulate. It extends from the withers and the back to the ventral edge of the thorax and the belly. It also Includes the posterior surface of the upper foreleg, and the anterior surface of the hindleg just below the knee (https://www.inaturalist.org/observations/3985830 and https://www.inaturalist.org/observations/38720040).

The pattern is one of horizontal banding on a broad design, in which the upper and lower panels are pale, with the flanks forming a dark median panel.

However, an important qualification is that the upper panel appears pale partly owing to sheen. Its conspicuousness thus depends on illumination.

https://www.dreamstime.com/stock-photo-bontebok-field-looking-perfect-medium-sized-generally-dark-brown-antelope-prominent-wide-white-image77512668

https://www.agefotostock.com/age/en/details-photo/bontebok-damaliscus-dorcas-dorcas-de-hoop-reserve-south-africa-africa/RHA-743-243/1

https://www.agefotostock.com/age/en/details-photo/bontebok-damaliscus-dorcas-dorcas-bovidae-antelope-mammal-animal-cape-of-good-hope-national-park-south-africa-africa/H44-10978980/1

https://www.alamy.com/stock-photo-bontebok-damaliscus-pygargus-pygarus-at-the-base-of-the-langeberg-59175692.html?imageid=FE1F6904-9478-4A53-8A24-5E8D481C7E90&p=22059&pn=3&searchId=6d8a7f95c3b92935b5e8c1d5d07d00ff&searchtype=0

https://www.alamy.com/bontebok-in-the-bontebok-national-park-swellendam-western-cape-south-africa-image342638387.html?imageid=5C55BBE5-4514-4B34-AEDA-ACC05175FD68&p=22337&pn=3&searchId=6d8a7f95c3b92935b5e8c1d5d07d00ff&searchtype=0

https://www.inaturalist.org/observations/113481398

https://www.inaturalist.org/observations/115575412

https://www.inaturalist.org/observations/80586175

https://www.alamy.com/stock-photo-bontebok-antelope-114770771.html?imageid=0A5EB348-1301-4DC3-B4AD-F99E5785ACEA&p=353301&pn=4&searchId=29c543d132619cf1217ce0a23a3945c6&searchtype=0

https://www.gettyimages.com.au/detail/photo/bonteboks-grazing-royalty-free-image/541049632?phrase=blesbok&adppopup=true

The design of the lateral bleeze of the bontebok is such that in bright sunlight at midday, when the ventral white is inconspicuous owing to shading, the dorsal sheen is 'switched on' owing to sheen (https://www.inaturalist.org/observations/27337501 and https://www.inaturalist.org/observations/27289820).

Comparison with blesbok:

A categorical difference is that, unlike the bontebok, the blesbok lacks a lateral bleeze.

The pelage of the flanks is not necessarily any paler in the blesbok than in the bontebok. However, the differences are that, in the blesbok,

• the dorsal sheen is poorly-developed,
• the pale ventral pelage is restricted, and reduced to a combination of countershading and an abdominal flag, and
• the white anterior edge of the hindleg, just below the knee, is narrower than in the bontebok.

Furthermore,

• the abdominal flag of the blesbok (https://www.inaturalist.org/observations/130975314) is subsumed within a broader white, ventral panel, so that the bontebok lacks an abdominal flag, and
• the ulnar dark/pale contrast of the blesbok - although just as clear in the bontebok - becomes an anterior extension of the ventral white of the thorax, so that the bontebok lacks an ulnar flag.

PYGAL BLEEZE

The pygal bleeze of the bontebok is about as large as the facial bleeze, but located at the opposite pole of the figure (https://www.alamy.com/stock-photo-a-pair-of-bontebok-antelopes-damaliscus-pygargus-dorcas-south-africa-85437994.html?imageid=8C3973B1-D533-4CA3-B604-463AAB155B2F&p=70019&pn=1&searchId=abde0ec3b06a08943ffb523ff66f0db0&searchtype=0 and https://www.dreamstime.com/stock-photo-bontebok-antelopes-pair-damaliscus-pygargus-dorcas-south-africa-image56821286).

The pale posterior feature of the bontebok

• extends from the rump to the tail-stalk and the buttocks immediately adjacent to the anus and perineum,
• is largely white, and
• contrasts with the dark pelage around it.

https://www.inaturalist.org/observations/80650367

https://www.inaturalist.org/observations/57714646

https://www.alamy.com/stock-photo-a-bontebok-damaliscus-pygargus-in-the-bontebok-national-park-near-173731691.html?imageid=75A1E59F-9E57-44B2-8852-46B50B30641E&p=77702&pn=6&searchId=d7a105eea18d32dc6155ddf3de390174&searchtype=0

https://www.inaturalist.org/observations/53977868

Comparison with blesbok:

The pygal flag of the blesbok bears the same relationship to the pygal bleeze of the bontebok as the abdominal flag of the blesbok (https://www.alamy.com/blesbok-in-savannah-south-africa-image151809725.html?imageid=3B900166-AC81-4937-96B6-1CA462655F62&p=703420&pn=10&searchId=26e0b007d6f642f3bb26a9cc6900a5cf&searchtype=0) bears to the white ventral panel of the lateral bleeze of the bontebok.

Furthermore, the pygal flag of the blesbok depends mainly on sheen effects, whereas the pygal bleeze of the bontebok depends mainly on the depigmentation of the pelage.

PEDAL FLAG

The lower legs of adults of the bontebok are largely white, making them conspicuous in locomotion.

https://www.inaturalist.org/observations/127885416

https://www.dreamstime.com/stock-photo-bontebok-antelope-running-velt-image65832109

https://www.alamy.com/bontebok-are-the-colourful-bok-of-south-africa-image228097057.html?imageid=7AAA4F55-17D1-423B-BF91-57470077439F&p=641396&pn=1&searchId=25869b8bb63848eab5bc67f94e53a679&searchtype=0

https://www.alamy.com/stock-photo-bontebok-antelope-17066360.html?imageid=AFA96455-2E25-41C8-91B0-1B7B94A1EA3C&p=4877&pn=1&searchId=abde0ec3b06a08943ffb523ff66f0db0&searchtype=0

https://www.alamy.com/stock-photo-bontebok-antelope-17066531.html?imageid=87C5DBB8-BEBE-41B5-A483-7EF7427CDD10&p=4877&pn=3&searchId=8e369419b3a055a70321251ed7501637&searchtype=0

Comparison with blesbok:

Both the bontebok and the blesbok possess a pedal flag. However, this feature is better-developed in the bontebok, in which

• the white pelage is more extensive, particularly on the outer surfaces of the lower legs, and
• there is less individual variation.

LACK OF AURICULAR FLAG

In the bontebok, there is a considerable sheen on the short, sparse pelage on the posterior surface of the ear pinnae. In some.views this produces a noticeably pale aspect to the back-of-ear.

However, after perusing hundreds of photos, I have not found this effect to be strong or consistent enough to qualify as an auricular flag. It is better-regarded as an incipient/residual version of the pattern in the blesbok (see below).

https://www.agefotostock.com/age/en/details-photo/bontebok-antelope/ESY-001254401/1

https://www.alamy.com/bontebok-antelope-damaliscus-pygargus-dorcas-south-africa-image156518411.html?imageid=FCBE4CA1-DBF7-4706-9D07-20EC04F83E25&p=476215&pn=1&searchId=abde0ec3b06a08943ffb523ff66f0db0&searchtype=0

https://www.inaturalist.org/observations/84604329#data_quality_assessment

https://www.alamy.com/stock-photo-bontebok-antelope-bontebok-national-park-swellendam-overberg-western-139221333.html?imageid=C6DAAADA-77BC-4140-AC0F-6ACCCDFABC9D&p=10587&pn=1&searchId=abde0ec3b06a08943ffb523ff66f0db0&searchtype=0

https://www.alamy.com/stock-photo-at-the-peaceful-and-quiet-bontebok-south-african-park-two-antelopes-32166159.html?imageid=143BD930-B2D0-433C-A84D-753F5F9CE194&p=94763&pn=1&searchId=abde0ec3b06a08943ffb523ff66f0db0&searchtype=0

https://www.inaturalist.org/observations/115550547

https://www.alamy.com/bontebok-walking-image647406.html?imageid=FF50FFAE-284D-4D2A-B72E-56FEB151968F&p=4877&pn=4&searchId=29c543d132619cf1217ce0a23a3945c6&searchtype=0

Comparison with blesbok:

The ear pinnae seem identical in size and pigmentation in the bontebok and the blesbok.

However, perusal of hundreds of photos shows that the sheeny quality of the posterior surface is better-developed in the blesbok (https://www.agefotostock.com/age/en/details-photo/blesboks-damaliscus-pygargus-phillipsi-two-adults-standing-in-open-grassland-alert-mountain-zebra-national-park-eastern-cape-south-africa-africa/ZI6-3207754/1 and https://www.agefotostock.com/age/en/details-photo/bontebok-south-africa/FHR-88889-04144-075/1) than in the bontebok.

This, together with the relatively poorly-developed sheen on the withers and back, qualifies the blesbok, in my view, for an auricular flag (https://www.inaturalist.org/journal/milewski/75905-unlike-the-blesbok-the-bontebok-damaliscus-pygargus-pygargus-lacks-an-auricular-flag#).

The lack of an auricular flag in the bontebok is significant evolutionarily. This is because all of the postcranial pale features are better-developed in the bontebok than in the blesbok.

LACK OF CAUDAL FLAG

The tail of the bontebok is large enough to be conspicuous, particularly because the white tail-stalk contrasts with the black tail-tassel (https://www.agefotostock.com/age/en/details-photo/bontebok-antelope/ESY-008277294/1). However, in terms of colouration, the tail is subsidiary to the pygal bleeze, which is the more conspicuous feature.

Furthermore, the bontebok displays its tail only in a few social contexts (e,g. courtship, https://www.alamy.com/stock-photo-bontebok-blesbok-antelope-damaliscus-damaliscus-dorcas-bovidae-male-36820913.html?imageid=D177A04E-5BB2-42A8-8538-B839CCC540E6&p=26096&pn=5&searchId=78e3c36a9917c21e07efdd82f4c4fbc0&searchtype=0), and not in alarm or fleeing. It does not seem to wag/swish the tail except in reaction to insects.

As a result, the bontebok does not, in my view, qualify for a caudal flag.

https://www.alamy.com/stock-photo-africa-south-africa-west-coast-national-park-bontebok-antelope-damaliscus-56090059.html?imageid=7A7DA0E1-EDD1-47FE-9168-012DC072ABCE&p=183410&pn=1&searchId=abde0ec3b06a08943ffb523ff66f0db0&searchtype=0

Comparison with blesbok:

The tail of the blesbok differs from that of the bontebok in that

• the whitish on the tail-stalk is less extensive (https://www.alamy.com/stock-photo-blesbok-blesbuck-antelope-highveld-grassland-sub-species-malolotja-33111001.html?imageid=BAF3FFD2-9161-4773-A68D-BA0F46CA3326&p=95996&pn=12&searchId=613ad7e0bd93e5b62ff61eccb1b0294f&searchtype=0), and
• the tail-tassel tends to have a pale ('blond') extension, reaching well below the hocks (https://www.inaturalist.org/journal/milewski/75827-a-previously-overlooked-difference-between-the-blesbok-and-the-bontebok-pale-vs-dark-tail-tassel#).

However, the blesbok likewise fails to qualify for a caudal flag. This is because

• the dark/pale contrast on the tail is less, not more, developed than in the bontebok, and
• the blesbok, like the bontebok, 'downplays' the tail in terms of demonstrations, particularly in the context of anti-predator behaviour.

DISCUSSION

The colouration of adults of the bontebok is configured in such a way that the figure is conspicuous, regardless of whether

• the observer is near or far (https://www.inaturalist.org/observations/74236727),
• the illumination is toplit (https://www.inaturalist.org/observations/10980022), frontlit (https://www.inaturalist.org/observations/71237026), or backlit (https://www.inaturalist.org/observations/202940),
• the figure is stationary or in motion, and
• the posture is standing or lying (https://www.dreamstime.com/stock-photography-bontebok-image4469222 and https://www.inaturalist.org/observations/71309846 and https://www.inaturalist.org/observations/141140171).

to be continued in https://www.inaturalist.org/journal/milewski/76336-adaptive-colouration-in-the-bontebok-damaliscus-pygargus-pygargus-part-2-infants-juveniles-and-adolescents#...

...continued from https://www.inaturalist.org/journal/milewski/75748-adaptive-colouration-in-the-blesbok-damaliscus-pygargus-phillipsi-part-1-adults#

The blesbok has uniform pale colouration at birth, which differs categorically from that of adults.

In juveniles of Damaliscus pygargus, the facial colouration is the inverse of that of adulthood, with the facial bleeze beginning dark, and the adjacent cheeks beginning pale (https://www.dreamstime.com/stock-photo-blesbuck-late-afternoon-field-blesbok-antelope-endemic-to-south-africa-has-distinctive-white-image77761757 and https://www.dreamstime.com/stock-photo-blesbuck-late-afternoon-field-blesbok-antelope-endemic-to-south-africa-has-distinctive-white-image77761766).

INFANTS (birth to three months old, including first appearance of horns)

The colouration of infants of the blesbok is categorically different from that of adults.

The ground-colour (including the posterior surfaces of the ear pinnae) is pale, with countershading. The tail-tassel is merely incipient.

The only distinct pattern is seen on the face, where the ground-colour of the rostrum and upper lips is crisply separated from whitish cheeks. Whitish extends on to the orbits except for the anterior side of the orbits.

https://www.zoobrno.cz/en/our-animals/animals-kept/mammals/2019-01-17-damaliscus-pygargus-phillipsi

https://www.zooborns.com/zooborns/2016/07/how-to-feed-a-baby-blesbok.html

https://www.shutterstock.com/it/image-photo/blesbuck-newborn-baby-89983321

https://www.shutterstock.com/it/image-photo/blesbok-blesbuck-calf-stays-close-members-1671765892

https://www.shutterstock.com/it/image-photo/blesbok-mother-small-calf-leaning-against-91405400

https://www.inaturalist.org/observations/37983324

https://www.zooborns.com/.a/6a010535647bf3970b016764fa98c6970b-popup

https://www.gettyimages.no/detail/news-photo/newborn-blesbok-calf-born-on-12-july-2013-rests-in-the-news-photo/1041931828?adppopup=true

https://stock.adobe.com/search/images?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=0&filters%5Bcontent_type%3Atemplate%5D=0&filters%5Bcontent_type%3A3d%5D=0&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=blesbok&order=relevance&price%5B%24%5D=1&safe_search=1&limit=100&search_page=3&search_type=pagination&get_facets=0&asset_id=49622738

https://www.gettyimages.no/detail/photo/blesboks-royalty-free-image/74077088?adppopup=true

https://www.gettyimages.com.au/detail/photo/blesboks-royalty-free-image/74077088?phrase=blesbok&adppopup=true

https://stock.adobe.com/search/images?k=blesbok&asset_id=544432933

https://stock.adobe.com/search/images?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=0&filters%5Bcontent_type%3Atemplate%5D=0&filters%5Bcontent_type%3A3d%5D=0&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=blesbok&order=relevance&price%5B%24%5D=1&safe_search=1&limit=100&search_page=3&search_type=pagination&get_facets=0&asset_id=410239969

https://www.gettyimages.no/detail/photo/female-blesbok-with-a-cream-coloured-calf-at-day-royalty-free-image/1073695294?adppopup=true

https://stock.adobe.com/search/images?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=0&filters%5Bcontent_type%3Atemplate%5D=0&filters%5Bcontent_type%3A3d%5D=0&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=blesbok&order=relevance&price%5B%24%5D=1&safe_search=1&limit=100&search_page=5&search_type=pagination&get_facets=0&asset_id=410240019

https://www.inaturalist.org/observations/10039715

https://www.inaturalist.org/observations/87530537

https://www.inaturalist.org/observations/41711968

https://unsplash.com/photos/ODftot2S_8g

https://www.robertharding.com/preview/741-3687/blesbok-damaliscus-dorcas-kariega-game-reserve-south-africa/

The maximum body size reached by offspring within the infantile colouration is shown in the second photo in https://www.inaturalist.org/observations/151282742.

JUVENILES

3-6 months old:

The rostrum, and to lesser degree the upper foreleg, abruptly turn dark. This produces a temporary 'inverse' version of the facial bleeze.

https://stock.adobe.com/search/images?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=0&filters%5Bcontent_type%3Atemplate%5D=0&filters%5Bcontent_type%3A3d%5D=0&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=blesbok&order=relevance&price%5B%24%5D=1&safe_search=1&limit=100&search_page=4&search_type=pagination&get_facets=0&asset_id=545134999

https://www.dreamstime.com/stock-photo-blesbuck-late-afternoon-field-blesbok-antelope-endemic-to-south-africa-has-distinctive-white-image77761762

https://pixabay.com/photos/africa-animals-blesbok-herd-2643568/

https://www.dreamstime.com/stock-photo-blesbuck-late-afternoon-field-blesbok-antelope-endemic-to-south-africa-has-distinctive-white-image77761765

https://www.alamy.com/blesbok-damaliscus-pygargus-phillipsi-lamb-leaping-mountain-zebra-image65490846.html?imageid=143E1B78-F9A0-4910-9888-57EADFEA42CE&p=94604&pn=1&searchId=187c1df722ae1d0911e278a028824aaf&searchtype=0

https://www.shutterstock.com/it/image-photo/blesbuck-143669233

https://stock.adobe.com/images/three-alert-blesbok-standing-on-dry-winter-grassland-landscape/168842499?as_campaign=ftmigration2&as_channel=dpcft&as_campclass=brand&as_source=ft_web&as_camptype=acquisition&as_audience=users&as_content=closure_asset-detail-page

https://www.alamy.com/juvenile-blesbok-damaliscus-pygargus-phillipsi-mountain-zebra-national-image65490812.html?imageid=E925F6B0-7DB8-4381-90A4-A1DB36C2A783&p=94604&pn=1&searchId=34a5985d254a7cecee5d7188055b6b4c&searchtype=0

https://www.alamy.com/blesbok-damaliscus-pygargus-phillipsi-ewe-and-lamb-mountain-zebra-image65490822.html?imageid=5FF38309-94A5-4D21-AAEA-4777C2D4463D&p=94604&pn=1&searchId=34a5985d254a7cecee5d7188055b6b4c&searchtype=0

https://stock.adobe.com/search/images?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=0&filters%5Bcontent_type%3Atemplate%5D=0&filters%5Bcontent_type%3A3d%5D=0&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=blesbok&order=relevance&price%5B%24%5D=1&safe_search=1&limit=100&search_page=4&search_type=pagination&get_facets=0&asset_id=545134999https://www.mediastorehouse.com/ardea-wildlife-pets-environment/asw-4602-1300433.html

https://www.mediastorehouse.co.uk/worldinprint/blesbok-damaliscus-pygargus-phillipsi-ewe-lamb-9643399.html

https://www.istockphoto.com/photo/very-cute-blesbok-antelope-juvenile-baby-laying-at-its-mothers-feet-on-the-ground-gm1367508274-437740167?phrase=pics%20of%20a%20blesbok

https://www.inaturalist.org/observations/122366216

https://www.alamy.com/juvenile-blesbok-damaliscus-pygargus-phillipsi-mountain-zebra-national-image65490807.html?imageid=B8EA5253-B43F-41C0-8B90-B1BD0FE8E257&p=94604&pn=1&searchId=34a5985d254a7cecee5d7188055b6b4c&searchtype=0https://www.gettyimages.no/detail/photo/blesbok-antelope-royalty-free-image/95006564?adppopup=true

https://www.agefotostock.com/age/en/details-photo/blesbok-damaliscus-dorcas-phillipsi-calf-walking-in-highveld-grassland-malolotja-n-p-swaziland/FHR-10014-00021-125

https://stock.adobe.com/search/images?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=0&filters%5Bcontent_type%3Atemplate%5D=0&filters%5Bcontent_type%3A3d%5D=0&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=blesbok&order=relevance&price%5B%24%5D=1&safe_search=1&limit=100&search_page=5&search_type=pagination&get_facets=0&asset_id=221414983

https://www.dreamstime.com/stock-images-young-blesbok-side-walking-past-image32075944

https://stock.adobe.com/search/images?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=0&filters%5Bcontent_type%3Atemplate%5D=0&filters%5Bcontent_type%3A3d%5D=0&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=blesbok&order=relevance&price%5B%24%5D=1&safe_search=1&limit=100&search_page=5&search_type=pagination&get_facets=0&asset_id=200580481

https://www.istockphoto.com/photo/female-and-male-blesbok-gm462033577-32318952?phrase=pics%20of%20a%20blesbokhttps://www.dreamstime.com/blesbok-antelope-blesbok-standing-southern-african-savanna-image107648592

https://stock.adobe.com/search/images?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=0&filters%5Bcontent_type%3Atemplate%5D=0&filters%5Bcontent_type%3A3d%5D=0&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=blesbok&order=relevance&price%5B%24%5D=1&safe_search=1&limit=100&search_page=9&search_type=pagination&get_facets=0&asset_id=56932934

Six months old (see https://journals.co.za/doi/pdf/10.10520/EJC116862 ):

Whitish hairs appear on the rostrum, creeping upwards from the nose.

https://www.inaturalist.org/observations/11088490

https://www.gettyimages.com.au/detail/news-photo/bunte-bock-damaliscus-dorcas-standing-in-undergrowth-in-the-news-photo/481653583?phrase=blesbok&adppopup=true

https://www.istockphoto.com/photo/spring-joy-gm157229462-22242556?phrase=pics%20of%20a%20blesbok

https://www.alamy.com/blesbok-damaliscus-pygargus-phillipsi-young-walking-in-open-grassland-alert-mountain-zebra-national-park-eastern-cape-south-africa-africa-image229930038.html

https://www.agefotostock.com/age/en/details-photo/blesbok-damaliscus-pygargus-phillipsi-young-walking-in-open-grassland-alert-mountain-zebra-national-park-eastern-cape-south-africa-africa/ZI6-3207756

6-12 months old:

At about one year old, pale appears on the forehead (individually variable). The rostrum (now pale) and tail-tassel (dark since birth) remain proportionately shorter than in adults.

https://www.inaturalist.org/observations/66790174

https://www.dreamstime.com/group-four-blesbok-antelope-stand-green-grass-field-one-them-grazing-others-looking-camera-trees-wildness-image182263733

ADOLESCENTS (1-2 years old, see https://journals.co.za/doi/pdf/10.10520/EJC116862)

https://www.dreamstime.com/blesbok-antelope-blesbok-southern-african-savanna-image107648073

https://www.dreamstime.com/stock-photo-blesbok-antelope-natural-habitat-damaliscus-pygargus-south-africa-image91058354

https://www.gettyimages.com.au/detail/photo/blesbok-antelope-royalty-free-image/497309877?phrase=blesbok&adppopup=true

https://www.agefotostock.com/age/en/details-photo/two-blesbok-damaliscus-pygargus-phillipsi-mountain-zebra-national-park-south-africa-africa/RHA-764-989/1

ADULTS (>2 years old, see https://journals.co.za/doi/pdf/10.10520/EJC116862)

https://www.shutterstock.com/it/image-photo/blesbok-blesbuck-damaliscus-dorcas-phillipsi-497011045

https://www.robertharding.com/preview/743-343/blesbok-damaliscus-dorcas-phillipsi-mountain-zebra-national-park/

Fully mature adults:

See https://www.inaturalist.org/journal/milewski/75871-a-previously-overlooked-aspect-of-the-bles-of-the-blesbok-signifying-full-maturity-within-adulthood#

DIFFERENCES FROM THE BONTEBOK

I have noticed then following tentative differences, which depend on further photographic evidence for verification:

• a small triangle of whitish pelage, located just above the rhinarium, is absent in infants of the blesbok, despite being present from the start in the bontebok,
• the fawn ground-colour is paler in infants of the blesbok (shown particularly clearly in https://www.zooborns.com/zooborns/2018/08/meet-betty-bantu-belfasts-blesbok-calf.html) than in those of the bontebok (https://www.dreamstime.com/royalty-free-stock-photography-blesbok-female-young-image12668777),
• the pale patch on the forehead is late to appear in the blesbok (https://www.shutterstock.com/it/image-photo/young-blesbok-south-africa-2119574858), despite being early to appear in the bontebok, and
• in juveniles, the temporary/transitional dark on the rostrum is darker, while the cheeks are paler, in the blesbok (https://www.istockphoto.com/photo/young-blesbok-gm947259792-258650817) than in the bontebok.

What this means is that infants, and particularly juveniles, are more conspicuous in the blesbok than in the bontebok - the inverse of the relationship between these two subspecies in adulthood.

Also see https://www.inaturalist.org/journal/milewski/76336-adaptive-colouration-in-the-bontebok-damaliscus-pygargus-pygargus-part-2-infants-juveniles-and-adolescents#.

(writing in progress)

The following photo-pair shows the two subspecies in posteriolateral view.

Both have a facial bleeze, that of the blesbok being proportionately larger owing to the difference in the relative sizes of the head.

The bontebok has an extremely well-developed pedal flag, whereas this individual of the blesbok, viewed in this perspective, lacks a pedal flag.

The pygal flag of the blesbok is replaced by a pygal bleeze in the bontebok.

In the blesbok, the abdominal and ulnar flags are separate, but in the bontebok there is a white ventral panel that subsumes both the abdominal and the ulnar pattern.

Blesbok
https://www.flickr.com/photos/dorneyphoto/49990958018/in/photolist-2jawJah-Hg63fU-bpxo9b-akqXjc-kDZnJt-8UcSMq-Sgocj4-2hdX4hz-2hRvAAH-2nqxXKA-2k7THja-2nFTwAK-NtcqZw-2mKwoFx-K9H7kw-2nYaeMv-2jbEesL-2jbJeMK-NwubQy-FGdmr3-CMZ9sW-2mVjjPf-ThNHJU-21La8WY-8xnKqU-eMntC3-KA9iEt-2kYpdSu-bsgrmu-2jxYMd5-b3zx7T-2hQhV25-jyHrKJ-2k5VFg7-5sqULW-2fkJEYZ-2kPChVk-21DVXBL-dRVYii-2kvQbEc-yRBxjS-EjKxsR-7cWLgq-21oyHh4-oD1wzM-eijdtU-2gmKAXS-7y3c7F-frYRFL-MdmiNW

Bontebok
https://www.inaturalist.org/observations/130669553

POSTERIOLATERAL VIEW

Blesbok
https://www.inaturalist.org/observations/5141221 and https://www.inaturalist.org/observations/10924282

Blesbok
https://www.inaturalist.org/observations/31573500

Blesbok
https://www.inaturalist.org/observations/85742476

Blesbok
https://www.inaturalist.org/observations/7916986

Blesbok
https://www.inaturalist.org/observations/71536880

Adult male bontebok
https://www.inaturalist.org/observations/115575412

https://www.inaturalist.org/observations/110874507

(writing in progress)