3. lokakuuta 2022

An attempted photo-guide to the subspecies of the steenbok (Raphicerus campestris) is partly a self-refuting exercise

@tonyrebelo @jeremygilmore @ludwig_muller @capracornelius @simontonge @tandala @geichhorn @michalsloviak @colin25 @alanhorstmann @jakob @jwidness @dejong @davidbygott @koosretief @gigilaidler

Today, I set out to illustrate - in the spirit of a field guide-book - the various subspecies of the steenbuck (Raphicerus campestris, https://www.inaturalist.org/taxa/42375-Raphicerus-campestris).

I was only partly successful, and this was not because of a lack of photos on the Web

Something important to realise, which has not emerged in the literature, is the following.

The northern subspecies (https://www.awl-images.com/stock-photo-kenya-taita-taveta-county-tsavo-east-national-park-a-steinbuck-image00398991.html) is only slightly different from the subspecies found in eastern South Africa (https://www.alamy.com/steenbok-raphicerus-campestris-adult-female-standing-on-the-ground-mpumalanga-south-africa-image384329875.html).

This is despite a wide geographical disjunction and the associated reproductive isolation.

It is instead the southernmost subspecies, living in a temperate zone, that is recognisable in photos.

What this means is that only two subspecies can be claimed with confidence, viz.

  • nominate campestris, and
  • neumanni, in a broadened sense.

The remaining subspecies (capricornis and steinhardti) are recognised mainly because of an assumption that their own wide geographical and climatic spread, from the edge of the Namib desert to the edge of miombo woodland in Zimbabwe, must surely be reflected in subspeciation.

It remains possible that even the adaptation to aridity within this species is (https://www.alamy.com/stock-photo-steenbok-raphicerus-campestris-desert-rhino-camp-damaraland-namibia-91113533.html?imageid=222AA12F-6CFE-4847-893B-A221FB5DEA88&p=71799&pn=2&searchId=61806f9903717abe80887586aa50fbc7&searchtype=0) is merely a matter of ecotypes, rather than a matter of subspeciation.

Another important point is that there is enough individual variation in the steenbok to blur any subspecies-distinctions.

The result:

The distinctions among neumanni, capricornis, and steinhardti are so slight that I have found it hard to compile any 'typical' photos of them, in which the subspecific differences are self-evident.

The following is my best attempt, after sifting through thousands of photos.

RAPHICERUS CAMPESTRIS CAMPESTRIS

Western Cape, South Africa

ground-colour dark

https://www.inaturalist.org/observations/98597843

https://www.inaturalist.org/observations/78046023

https://www.inaturalist.org/observations/52877690

forehead rich-hued

https://stock.adobe.com/ro/images/big-ears/441156073?prev_url=detail

white features (except for buttocks) minimal, particularly on face and inner upper hindleg

https://www.shutterstock.com/image-photo/cape-grysbok-184337792

https://www.istockphoto.com/photo/grysbok-cape-gm1134456769-301460055?phrase=grysbok

RAPHICERUS CAMPESTRIS STEINHARDTI

Namibia except for eastern Caprivi, most of Botswana, most of Northern Cape of South Africa, southern Angola

ground colour pale

https://www.alamy.com/steinbuck-raphicerus-campestris-hoanib-river-namibia-image61349728.html?imageid=205095BC-DD65-4197-BB81-B5D2B32724DD&p=191343&pn=1&searchId=30e86c64bd74ac276119489cea99aea1&searchtype=0

size of ear pinnae maximal

https://stock.adobe.com/ro/video/close-up-from-a-steenbok-resting-at-the-hoanib-riverbed-in-namibia/322384062?prev_url=detail

radial gland noticeable

https://stock.adobe.com/ro/images/cute-steenbok-on-alert-in-front-of-tree-in-etosha-national-park/404356409?prev_url=detail

RAPHICERUS CAMPESTRIS CAPRICORNIS

Mpumalanga, Limpopo, northeastern Kwazulu-Natal, eSwatini, southern Mozambique, Zimbabwe, eastern Caprivi of Namibia, eastern and northeastern Botswana, southwestern Zambia

forehead rich-hued

https://stock.adobe.com/ro/images/male-steenbok-raphicerus-campestris-in-orange-morning-light/313363014?prev_url=detail

https://www.alamy.com/steenbok-raphicerus-campestris-kruger-national-park-south-africa-image237971244.html?imageid=0B54B740-4FC0-4227-931B-0B0098D4D6CD&p=22059&pn=1&searchId=3309ba2d8d68889a061642cd2d5bc830&searchtype=0

size of ear pinnae minimal

https://www.alamy.com/stock-photo-steenbok-raphicerus-campestris-in-a-dry-meadow-south-africa-krueger-76132016.html

radial gland noticeable

https://stock.adobe.com/ro/images/steinbockchen-kruger-national-park-sudafrika/226378977?prev_url=detail

https://stock.adobe.com/ro/images/steenbok-mammal-of-the-kruger-national-park-reserves-and-parks-of-south-africa/273120689?prev_url=detail

RAPHICERUS CAMPESTRIS NEUMANNI

Kenya, Tanzania

Despite the geographical isolation of the East African part of the species-distribution, I have failed to find any consistent difference between this supposed subspecies and capricornis.

https://www.inaturalist.org/observations/135970683

https://www.gettyimages.co.uk/detail/photo/dik-dik-in-the-serengeti-tanzania-east-africa-royalty-free-image/1203979753?adppopup=true

https://www.inaturalist.org/observations/94106167

Lähetetty 3. lokakuuta 2022 16:22 käyttäjältä milewski milewski | 8 kommenttia | Jätä kommentti

2. lokakuuta 2022

Selected views of the bambi genus Madoqua, plus noteworthy photos mislabelled as dikdiks on the Web

MADOQUA KIRKII DAMARENSIS

https://www.inaturalist.org/observations/72199054

https://www.inaturalist.org/observations/11220482

https://stock.adobe.com/images/a-female-kirk-s-dik-dik-antelope-smallest-in-the-world-standing-in-the-bush-etosha-national-park-in-nambia-africa/138389109?prev_url=detail

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=dikdik&order=relevance&safe_search=1&limit=100&search_page=3&get_facets=0&search_type=pagination&asset_id=296756341

showing anomalous whitish at knee
https://www.inaturalist.org/observations/92816759

https://stock.adobe.com/images/kirk-s-dik-dik/11627412?prev_url=detail

The following shows how the accentuation of the eye seems to undermine the cryptic colouration:

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=dikdik&order=relevance&safe_search=1&limit=100&search_page=4&search_type=pagination&get_facets=0&asset_id=357094861

https://stock.adobe.com/search?k=dikdik&asset_id=71439139

https://upload.wikimedia.org/wikipedia/commons/7/75/Damara_Dik-Dik.JPG

https://stock.adobe.com/search?k=dikdik&asset_id=77363734

https://www.sciencephoto.com/media/873025/view/damara-dik-dik

https://ekujasafari.com/hunting-darma-dik-dik-namibia/

https://stock.adobe.com/search?k=dikdik&asset_id=60051921

https://stock.adobe.com/search?k=dikdik&asset_id=280950356

MADOQUA KIRKII KIRKII

https://www.gettyimages.co.uk/detail/photo/dik-dik-is-a-small-antelope-royalty-free-image/520027099?adppopup=true

https://www.gettyimages.co.uk/detail/photo/cute-little-dik-dik-antelope-making-funny-face-in-royalty-free-image/1176116863?adppopup=true

https://stock.adobe.com/images/dik-dik/28620223?prev_url=detail

https://stock.adobe.com/images/small-antelope-in-the-bush-on-safari-in-kenya/132504921?prev_url=detail

https://stock.adobe.com/images/a-dik-dik-a-small-antelope-in-africa-lake-manyara-national-par/76987496?prev_url=detail

https://stock.adobe.com/search?k=dikdik&asset_id=64450247

https://www.jungledragon.com/image/116371/dik-dik_antelope.html/zoom

https://www.dreamstime.com/stock-photo-kirks-dikdik-female-portrait-side-side-to-camera-just-inches-high-shoulder-second-smallest-image83518357

https://stock.adobe.com/images/young-african-thompson-s-gazelle-in-serengeti-national-park-tanzania/312477243?prev_url=detail

https://www.vecteezy.com/photo/844782-kirk-s-dik-dik-madoqua-kirkii-damara-dikdik-kirk-dik

https://naturerules1.fandom.com/wiki/Kirk%27s_Dik-dik?file=96bf2c9bad44e82e8bc041c27497e5d9.jpg

https://wildlifesafari.info/kirks_dikdik.html

https://www.agefotostock.com/age/en/details-photo/kirk-s-dikdik-kirk-s-dik-dik-damara-dik-dik-madoqua-kirkii-pair-in-its-habitat-kenya-samburu-national-reserve/BWI-BS371737

https://stock.adobe.com/search?k=dikdik&asset_id=357153060

https://stock.adobe.com/search?k=dikdik&asset_id=46502141

https://stock.adobe.com/search?k=dikdik&asset_id=245343557

https://stock.adobe.com/search?k=dikdik&asset_id=315354748

https://stock.adobe.com/search?k=dikdik&asset_id=464916173

https://stock.adobe.com/search?k=dikdik&asset_id=437570754

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=dikdik&order=relevance&safe_search=1&limit=100&search_page=3&get_facets=0&search_type=pagination&asset_id=311845908

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=dikdik&order=relevance&safe_search=1&limit=100&search_page=2&get_facets=0&search_type=pagination&asset_id=405151508

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=dikdik&order=relevance&safe_search=1&limit=100&search_page=2&get_facets=0&search_type=pagination&asset_id=139409377

https://stock.adobe.com/search?k=dikdik&asset_id=308981505 and https://stock.adobe.com/search?k=dikdik&asset_id=308981470

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=dikdik&order=relevance&safe_search=1&limit=100&search_page=2&get_facets=0&search_type=pagination&asset_id=370598519

MADOQUA SALTIANA

https://upload.wikimedia.org/wikipedia/commons/5/5d/Salts_Dikdik.jpg

MADOQUA GUENTHERI

https://stock.adobe.com/search?k=dikdik&asset_id=94546206

https://www.researchgate.net/figure/Adult-female-Guenthers-dik-dik-Madoqua-guentheri-guentheri-Garissa-central-east_fig7_319302047

https://stock.adobe.com/search?k=dikdik&asset_id=464916125

https://www.gettyimages.co.uk/detail/photo/madoqua-guentheri-royalty-free-image/134231011?adppopup=true

Lähetetty 2. lokakuuta 2022 23:16 käyttäjältä milewski milewski | 25 kommenttia | Jätä kommentti

1. lokakuuta 2022

A new hypothesis for the steenbok (Raphicerus campestris) in the Highveld of South Africa: it was naturally absent

@paradoxornithidae @matthewinabinett @dejong @tonyrebelo @jeremygilmore @ludwig_muller @dewald2 @henrydelange @koosretief @jakob @justinhawthorne @botswanabugs @capracornelius

It is easy to assume that the steenbok (Raphicerus campestris) was indigenous to the Highveld (https://en.wikipedia.org/wiki/Highveld) when European explorers arrived.

However, I suggest that it was actually absent.

This would help to explain why its current taxonomic status in the Highveld is so nebulous (https://www.inaturalist.org/journal/milewski/70638-the-steenbok-raphicerus-campestris-in-the-highveld-a-simple-question-gone-impossibly-complex#).

My argument is based on an ecological rationale, but seems consistent with the historical record.

The steenbok tends to be taken for granted as widespread and ecologically tolerant. However, it is more ecologically specialised than first it seems, in diet and habitats.

This species is part of a guild of relatively small herbivores including

All eat both grasses and dicotyledonous plants, in various combinations according to the seasons (https://www.researchgate.net/publication/230164079_The_feeding_ecology_of_a_very_small_ruminant_the_steenbok_Raphicerus_campestris).

Because it has so many competitors, R. campestris may have been somewhat limited in occurrence in prehistoric South Africa, when the full fauna of the Holocene remained.

The Highveld contained by far the most complex fauna of ungulates of any region of treeless grassland on Earth (https://www.sciencedirect.com/science/article/pii/S0254629915003051 and https://www.researchgate.net/publication/282619832_Why_was_the_Highveld_treeless_Looking_laterally_to_the_Pampas_for_global_edaphic_principles_beyond_biogeographical_accidents). This may have precluded a niche for R. campestris under natural conditions.

I suspect that it was only when the fauna was disrupted by human settlement that R. campestris spontaneously entered the Highveld, from the west and north.

The idea is that it filled in for the species virtually exterminated by settlers, particularly the formerly abundant and migratory A. marsupialis.

This is not to claim that R. campestris became abundant in the Highveld, but merely that it became viable there because of, rather than despite, anthropogenic disturbance.

Three subspecies were thus hypothetically recruited to the Highveld, then mixing there through hybridisation. These are R. c. campestris (southwesterly origin), R. c. steinhardti (northwesterly origin), and R. c. capricornis (northeasterly origin).

Another basis for my hypothesis is habitat, particularly the natural availability of cover.

In its original state, the Highveld was treeless over extensive areas, partly owing to the intense natural herbivory. This hypothetically made the grassland too open for R. campestris.

There are two situations, in the Highveld today, with some shrubby indigenous cover, viz.

  • perennial drainage lines, and
  • scattered rocky outcrops.

However,

The settlement of the Highveld has boosted the incidence of woody plants, for various reasons.

I have before me du Plessis S F (1969, The Past and Present Geographical Distribution of the Perissodactyla and Artiodactyla in Southern Africa).

On page 100, du Plessis states for 'Orange Free State':
"Though no doubt occurring everywhere in this province in the past, practically no written records could be traced...Only Smith (Kirby, 1939) in 1835 mentions it as being common near the confluence of the Riet and Modder rivers".

This location (https://en.wikipedia.org/wiki/Riet_River) is actually west of Free State province and the Highveld, being located in the current Mokala National Park (https://en.wikipedia.org/wiki/Mokala_National_Park).

Much of the Highveld occurs in the former Transvaal (https://en.wikipedia.org/wiki/Transvaal_(province)). However, once again du Plessis (1969) largely draws a blank in the historical record.

The exceptions are as follows:

  • "Mauch (Petermann, 1870): north of Lydenburg"
  • "Holub (1881): near the Vaal River in western Transvaal"
  • "Holub (1890): between Bloemhof and Christiana"
  • "Baldwin (1894): the vicinity of Potchefstroom"
  • "Randall (1895): the open flats in the Barberton District."

The relevant locations mentioned are:

All of these are rather marginal to the Highveld, except for Potchefstroom. However, the latter is located in the valley of a major drainage line (https://en.wikipedia.org/wiki/Mooi_River_(Vaal)).

On page 103, du Plessis states the incidence, as of 1969, as follows:
"Orange Free State: Van Ee (1962): fairly generally distributed throughout the province with the greatest numbers along the rivers and in the mountainous districts of the east, especially in the Fouriesburg, Tweeling, Petrus Steyn, Boshoff, Theunissen, Brandfort, Hoopstad and Koffiefontein districts. Roberts (1963): 45 in the Willem Pretorius Game Reserve".

The status in Transvaal (page 104) was similarly widespread, as of 1969.

So, dear readers, please prove me wrong in my suggestion that the steenbok was naturally absent from the Highveld, including virtually the whole of what is now Free State.

One way to do so might be to consult a work to which I currently lack access. This is by Skead (https://en.wikipedia.org/wiki/CJ_Skead), covering that part of the Highveld falling within the Eastern Cape (https://ace.mandela.ac.za/Historical-Incidence-of-the-Larger-Mammals/Authors/The-works-of-Cuthbert-John-(Jack)-Skead),

In the meantime, the following is a compendium of all the current photos of R. campestris, located in the Highveld, in iNaturalist:

https://www.inaturalist.org/observations/129166689
https://www.inaturalist.org/observations/105216875
https://www.inaturalist.org/observations/108317173
https://www.inaturalist.org/observations/69266940
https://www.inaturalist.org/observations/127743228
https://www.inaturalist.org/observations/127670769
https://www.inaturalist.org/observations/98953074
https://www.inaturalist.org/observations/130857789

Only four of the above observations show the animals clearly.

Lähetetty 1. lokakuuta 2022 06:54 käyttäjältä milewski milewski | 6 kommenttia | Jätä kommentti

30. syyskuuta 2022

The steenbok (Raphicerus campestris) in the Highveld: a simple question gone impossibly complex?

It strikes me that the relationship between Raphicerus campestris (https://www.inaturalist.org/taxa/42375-Raphicerus-campestris) and the Highveld (https://en.wikipedia.org/wiki/Highveld) is particularly complicated and obscure.

On the face of it, one might have expected this relationship to be simple.

After all, R. campestris is typical of open, grassy vegetation, and the Highveld is a fairly discrete region within which it would be reasonable to expect just one, easily recognisable, subspecies of R. campestris.

But, in reality, there are at least four factors that cloud everything.

Firstly, the 'sour' type of Highveld, consisting of unpalatable, fire-prone grasses on poor soils under relatively copious rainfall, lacks R. campestris completely.

Secondly, even within the 'sweet' type of Highveld, consisting of palatable, fire-free grasses on rich soils under relatively sparse rainfall, R. campestris seems oddly uncommon, and overlooked/ignored in the records of the first European explorers of the 1800's.

Thirdly, the history of scientific collection of R. campestris happens to have been such that, as if by accident, the maximum uncertainty has arisen in the relationship of candidate sspp. fulvorubescens, 'natalensis', zuluensis, and capricornis to the Highveld.

Fourthly, the political (country/province) boundaries in the Highveld are complex and (https://www.intergate-immigration.com/blog/south-african-provinces/), have changed names recently, and have scant relationship to ecological boundaries.

So much so that they continue to hinder, rather than help, any biogeographical study of the region.

For iNaturalists other than South Africans, I can summarise this problem as follows.

The Latin specific name 'campestris' simply means 'of the veld'.

('Veld' is Afrikaans for 'field'.)

The main/typical area of 'veld' is the Highveld.

Yet, as things stand, it seems beyond us to account for the occurrence of R. campestris in the Highveld, past or present, in any coherent way, including even the subspecies concerned.

South Africa has been intensively studied by naturalists.

Yet, somehow, we seem to remain as mystified about the steenbok - possibly the 'commonest' small wild ungulate in the country - on the Highveld as we might be about some newly-discovered species of duiker in the equatorial Congo.

Lähetetty 30. syyskuuta 2022 23:36 käyttäjältä milewski milewski | 2 kommenttia | Jätä kommentti

29. syyskuuta 2022

A gland new to Science, hiding in plain sight on the steenbok (Raphicerus campestris)?

@dejong

There seems to be a gland in the steenbok (Raphicerus campestris), plainly visible in hundreds of photos (e.g. https://stock.adobe.com/search?k=steenbok&asset_id=404356409), that has not been recorded by any zoologist - until now.

This apparently glandular feature is noteworthy, because

  • its location seems unique among ungulates, and possibly among all animals, and
  • no trace of this dark vertical streak is visible in the other two spp. of the same genus, namely Raphicerus melanotis and R. sharpei.

I will call this feature the radial gland, because it is situated on the outer surface of the upper foreleg, where the main bone is the radius (https://www.inaturalist.org/observations/6316536).

This location is near the carpal joint. However, it differs from that of a gland long-recognised in other genera. I refer to the carpal gland, located on the anterior surface of the carpal joint.

The discovery of an additional gland in R. campestris would make sense, because this species has seemed puzzlingly poorly endowed with glands, compared to, for example, Ourebia ourebi.

Estes (1991, page 45) states that the scent glands of R. campestris comprise "smallish preorbital glands, larger in male, pedal glands in all feet, no inguinal glands, and possibly a throat gland (Smithers 1983)".

No author has mentioned any gland on the upper foreleg of any species of Raphicerus.

For comparison, Estes (1991, page 57) states that the scent glands of Ourebia ourebi comprise "very large preorbital glands in males (unused and possibly undeveloped in females); black spot below ear underlain by apocrine glands which diffuse scent into air (Kingdon 1982); deep inguinal pouches; carpal glands beneath brushes of long hair on front legs (as in gazelles), shorter brushes below hocks; well-developed glands between all hooves".

The carpal glands of Gazella and Ourebia presumably function by means of kneeling (https://blog.londolozi.com/2022/01/04/the-secret-life-of-a-steenbok/), which the animals perform every time they lie down or get up from the resting posture adopted for rumination. This would leave scent on the earth or herbage.

In the corresponding position on the front of the carpal joint, R. campestris simply has a small callus (https://en.wikipedia.org/wiki/Callus).

The hair-tufts covering the carpal glands are clearly visible in the following, because of their pigmentation:

The location of the radial gland in R. campestris is different enough from that of the carpal glands to make a similar function unlikely.

Furthermore, the radial gland seems bare of pelage, the dark appearance being that of bare but callus-free skin.

The following (https://stock.adobe.com/search?k=dikdik&asset_id=493868805) shows that the radial gland is at least as large as the preorbital gland (https://en.wikipedia.org/wiki/Preorbital_gland), which is the main gland associated with masculinity in R. campestris.

Casting some doubt on the glandular nature of this feature is the occurrence, in a few individuals of R. campestris, of a corresponding dark feature - where the hairs seem to have been worn off - on the hindleg:

https://www.gettyimages.com.au/detail/news-photo/female-steenbok-in-the-jao-concession-okavango-delta-in-news-photo/1200531573?adppopup=true

https://www.gettyimages.com.au/detail/news-photo/female-steenbok-in-the-jao-concession-okavango-delta-in-news-photo/1200531605?adppopup=true

https://www.gettyimages.com.au/detail/news-photo/close-up-of-a-female-steenbok-feeding-in-the-jao-concession-news-photo/1200531612?adppopup=true

https://www.gettyimages.com.au/detail/photo/female-steenbok-royalty-free-image/628346620?adppopup=true).

Intriguingly, the available photographic evidence suggests that there is subspecific variation in the incidence of the radial gland.

This feature seems to be particularly poorly-developed in R. campestris campestris, which is also the most distinctive subspecies in general colouration.

The following show the presence of the radial gland in various subspecies and both sexes of R. campestris.

campestris, female:

https://www.alamy.com/stock-photo-steenbok-raphicerus-campestris-nursing-karoo-national-park-south-africa-20458147.html?imageid=6D8944F6-61A5-46A2-AC95-2E9833E4259A&p=40779&pn=1&searchId=81afea0714a7b7094a750bf43216e26d&searchtype=0

https://www.inaturalist.org/observations/98392799

https://www.inaturalist.org/observations/41908928

https://www.alamy.com/weibliches-steinbckchen-hlt-ausschau-female-steenbok-looking-out-raphicerus-campestris-namaqualand-sdafrika-image333121951.html?imageid=BE16C88D-4083-4926-ACBC-3FDF6B393BAC&p=1151839&pn=1&searchId=c9304c518b7bb098e6083b00691cb84a&searchtype=0

campestris, male:

(many photos are available on the Web, but none show the feature in question)

capricornis, female:

https://www.istockphoto.com/photo/steenbuck-gm583977962-99962993?phrase=steenbok

https://www.istockphoto.com/photo/steenbok-ewe-kruger-national-park-gm1401423583-454646848?phrase=steenbok

https://www.istockphoto.com/photo/steenbok-standing-alert-gm524396756-92197869?phrase=steenbok

https://www.gettyimages.com.au/detail/photo/the-steenbok-royalty-free-image/636770832?adppopup=true

https://www.inaturalist.org/observations/94425108

https://www.alamy.com/stock-photo-steenbok-raphicerus-campestris-pup-in-evening-light-grazing-south-76132026.html?imageid=8D8D4245-9F6E-4BD8-8429-6E27576B9C46&p=68577&pn=1&searchId=c9304c518b7bb098e6083b00691cb84a&searchtype=0

capricornis, male:

https://www.istockphoto.com/photo/capricorn-in-green-savanna-gm1184254719-333285629?phrase=steenbok

https://www.istockphoto.com/photo/steenbuck-gm583977682-99962713?phrase=steenbok

https://www.istockphoto.com/photo/steinbuck-in-kruger-national-park-in-south-africa-gm1313842690-402234870?phrase=steenbok

https://www.istockphoto.com/photo/steenbok-raphicerus-campestris-gm495952922-78292089?phrase=steenbok

https://www.istockphoto.com/photo/steenbok-gazelle-gm1077769610-288723218?phrase=steenbok

https://www.istockphoto.com/photo/capricorn-gm1286648370-383087965?phrase=steenbok

https://www.istockphoto.com/photo/steenbok-antelope-gm487464396-72932291?phrase=steenbok

https://www.tripadvisor.co.uk/LocationPhotoDirectLink-g312618-i1689945-Kruger_National_Park.html

https://www.gettyimages.com.au/detail/photo/steenbok-adult-male-feeding-kruger-nationalpark-royalty-free-image/1209482706?adppopup=true

https://www.gettyimages.com.au/detail/photo/kruger-national-park-royalty-free-image/592939385?adppopup=true

https://www.inaturalist.org/observations/62689596

steinhardti, female:

https://www.inaturalist.org/observations/26661297

https://en.wikipedia.org/wiki/Steenbok#/media/File:Raphicerus_campestris_female_(Etosha,_2012).jpg

https://www.istockphoto.com/photo/steenbok-in-kgalagadi-transfrontier-park-south-africa-gm1392343427-448616170?phrase=steenbok

https://www.inaturalist.org/observations/100241068

https://www.gettyimages.com.au/detail/photo/steenbok-royalty-free-image/148697094?adppopup=true

https://www.inaturalist.org/observations/36941231

https://www.inaturalist.org/observations/36127710

steinhardti, male:

https://en.wikipedia.org/wiki/Steenbok#/media/File:Raphicerus_campestris_male_(Etosha,_2012).jpg

https://www.istockphoto.com/photo/steen-buck-walks-through-the-long-grass-in-the-kalahari-desert-south-africa-gm1351983424-427535947?phrase=steenbok

https://www.istockphoto.com/photo/steinbuck-antelope-looking-at-camera-in-etosha-national-park-namibia-gm540862142-96671299?phrase=steenbok

https://www.gettyimages.com.au/detail/photo/steenbok-etosha-pan-namibia-royalty-free-image/970408986?adppopup=true

https://www.inaturalist.org/observations/53130004

https://www.inaturalist.org/observations/50249368

https://www.inaturalist.org/observations/36127707

https://www.inaturalist.org/observations/34610708

https://www.istockphoto.com/photo/steenbok-raphicerus-campestris-small-shy-beautiful-antelope-from-african-savannah-gm1215318410-353932104?phrase=steinbok

neumanni, female:

https://www.alamy.com/steinbuck-raphicerus-campestris-tanzania-image6357425.html?imageid=4FC75135-114E-472E-ADBC-3951BA2051C7&p=2585&pn=1&searchId=30e86c64bd74ac276119489cea99aea1&searchtype=0

https://www.inaturalist.org/observations/18053713

https://www.inaturalist.org/observations/12006271

neumanni, male:

https://www.gettyimages.co.uk/detail/photo/dik-dik-in-the-serengeti-tanzania-east-africa-royalty-free-image/1203979753?adppopup=true

https://www.alamy.com/stock-photo-closeup-of-steenbok-scientific-name-raphicerus-campestris-or-funo-170650319.html?imageid=BC8588CB-D22B-4102-8E3C-A1BCE9BD9545&p=141090&pn=1&searchId=c9304c518b7bb098e6083b00691cb84a&searchtype=0

https://www.inaturalist.org/observations/32006732

FOOTNOTE:

The whole skin in Raphicerus campestris, apart from most of the anterior surface of the ear pinnae (https://stock.adobe.com/search?k=steenbok&asset_id=221530819), seems to be darkly pigmented.

This includes

The darkness of the skin shows through the pelage, around the eyes of R. melanotis and R. sharpei (but not R. campestris except for the preorbital gland), on the posterior surface of the ear pinnae in all three spp., and on the lower part of the buttocks of R. campestris when the pelage is matted.

Even the tongue is so dark-pigmented in R. campestris that it can be called black (https://www.mirror.co.uk/news/world-news/oh-deer-huge-python-spends-6367197 and https://www.alamy.com/stock-photo-a-steenbok-looking-camera-while-it-eats-leaves-off-tree-kgalagadi-40211532.html and https://fineartamerica.com/featured/portrait-of-a-steenbok-john-haldane.html).

Lähetetty 29. syyskuuta 2022 04:32 käyttäjältä milewski milewski | 17 kommenttia | Jätä kommentti

28. syyskuuta 2022

A working approach to subspecies distinctions in the steenbok, Raphicerus campestris

@alanhorstmann @tonyrebelo @jakob @jeremygilmore @ludwig_muller @jwidness @colin25 @geichhorn @henrydelange @koosretief @michalsloviak @alexdreyer @chewitt1 @oviscanadensis_connerties @capracornelius @tandala

The subspecies of the steenbok (Raphicerus campestris, https://www.inaturalist.org/taxa/42375-Raphicerus-campestris) were revised by Groves and Grubb (2011, Ungulate Taxonomy). However, please see https://www.zoochat.com/community/threads/ungulate-taxonomy-revisited-the-evidence-for-the-splits-of-g-g.467230/page-3.

The treatment of Groves and Grubb largely follows that of Roberts A (1951, The Mammals of South Africa).

Until now, iNaturalist has avoided the problem of subspecies, by simply distinguishing the widely disjunct East African form, neumanni, from the nominate form of southern Africa.

The current approach, in iNaturalist, does not do justice to the subspecific distinctions in R. campestris. This is because

  • the East African form does not look particularly distinctive, despite its geographical disjunction,
  • the southwesternmost form, of Western Cape, is obviously distinctive despite grading continuously with other forms to the north and to the east, and
  • the form penetrating the edges of the Namib desert is so ecologically extreme that it should be assumed to belong to an arid-adapted subspecies, unless proven otherwise.

Therefore, what seems most plausible is some compromise between the current 'lumped' approach, of only two subspecies, and the old, 'split' approach in which seven subspecies are recognised, viz.

  • campestris (southwestern parts of South Africa)
  • fulvorubescens (Eastern Cape and adjacent areas)
  • natalensis (eastern parts of South Africa, as far north as Gauteng and the high-lying parts of Mpumalanga)
  • zuluensis (Zululand and the low-lying parts of Mpumalanga)
  • capricornis (Limpopo province through Zinbabwe to the Zambezi valley)
  • steinhardti (Namibia, southern Angola, northwestern South Africa, and presumably southern Angola)
  • neumanni (Kenya and Tanzania).

On the basis of photographic evidence, the main, obvious distinction is between the dark form of the southwesternmost part of South Africa, and the rest of the species-distribution. There seems no doubt that the nominate form, i.e. subspecies campestris, deserves recognition. This is true notwithstanding the uncertainty of its northern and eastern limits, where it intergrades with adjacent forms.

It also remains fair to assume that the disjunct form of East Africa, namely neumanni, is a valid subspecies. This is notwithstanding the surprising fact that, based on photos, it looks hardly different from the form in eastern South Africa.

This brings us to the arid-adapted, western form, the main distinctive feature of which, based on photos, is the extreme enlargement of the ear pinnae, at least in some individuals.

On one hand, it is possible that the western populations are merely an ecotype, as opposed to a subspecies. This is because the colouration is similar to eastern forms, apart from the usual tendency to pallor, that is so familiar in animals living in semi-deserts.

On the other hand, we should bear in mind that the western populations are globally unique, in ecological terms.

There is no ungulate, worldwide, of body mass less than 15 kg, that penetrates the edge of desert, other than R. campestris (https://www.inaturalist.org/observations/11048622).

A remarkable fact is that R. campestris lives both at the edge of the barren Namib, in Namibia, and under a mesic, equatorial climate in west-central Kenya.

So, it seems reasonable to recognise the subspecies steinhardti, the type location of which (https://en.wikipedia.org/wiki/Fransfontein) is in northwestern Namibia.

This leaves us with the mesic regions of southern Africa, from Eastern Cape through Free State and Kwazulu-Natal to Mozambique, Mpumalanga and Limpopo, and northwards through southeastern and western Zimbabwe to northeastern Botswana and western Zambia.

According to Roberts (1951), subspecies capricornis, of western Zimbabwe, is distinctive in nearly lacking the dark, V-shaped marking on the crown, that is normal in other subspecies (https://www.inaturalist.org/observations/136478014).

In support of a subspecific distinction, it is obvious from photos that the ears are, at least in some individuals, extremely small in Kruger National Park, in Limpopo province of South Africa.

However, it is easy to show that the dark, V-shaped marking on the crown does remain, at least faintly, even in

This seems to contradict Roberts (1951).

Given the doubtful distinctions among the various eastern populations, perhaps we should choose whichever name takes chronological priority.

The choices are

  • fulvorubescens 1822, 'Caffraria', Eastern Cape
  • natalensis 1907, 'Drakensberg, Natal'
  • zuluensis 1946, Umfolozi, now in northern Kwazulu-Natal
  • capricornis 1906, Klein Letaba, now in Kruger National Park.

It seems likely that the populations in Eastern Cape represent intergradation with the nominate subspecies.

The name 'natalensis' seems to be invalid, i.e. a nomen nudum (see comment below).

Therefore, it resolves to a choice among the remaining two, and capricornis takes priority.

On this basis, I suggest that we provisionally recognise Raphicerus campestris capricornis (Thomas & Schwann, 1906).

In summary, I propose that we adopt the following subspecific names in iNaturalist:

  • campestris (Western Cape and adjacent parts of Northern Cape and Eastern Cape)
  • capricornis (northern Kwazulu-Natal, Mpumalanga, Limpopo, Gauteng, Mozambique, Zimbabwe, Zambia, easternmost Botswana, northeasternmost parts of both Namibia and Botswana)
  • steinhardti (Namibia, Angola, most of Botswana, most of Northern Cape)
  • neumanni (Kenya, Tanzania).

In all other regions, just identify to species-level, owing to the likelihood of intergradation. This includes the whole of Free State and North West (https://en.wikipedia.org/wiki/North_West_(South_African_province)), the eastern half of Eastern Cape, and eastern Botswana adjacent to Zimbabwe.

I leave readers with a few, carefully selected photos, illustrating the range of variation in the appearance of R. campestris.

The following shows how dark the nominate subspecies can be (https://www.inaturalist.org/observations/11241069). There is considerable individual variation in R. campestris, but no individual of any other subspecies is anywhere near as dark as this.

The following show the extreme variation in the size of the ear pinnae within R. campestris (https://www.shutterstock.com/image-photo/sharpes-grysbok-standing-shade-1917779507 vs http://www.rupavadodaria.com/my-first-veganniversary/).

The following show the variation in the dark marking in the rostrum, adjacent to the rhinarium. This is absent in some individuals of R. c. steinhardti (https://www.inaturalist.org/observations/6611664), whereas it reaches to between the eyes in some individuals of R. c. capricornis (https://www.alamy.com/male-steenbok-raphicerus-campestris-kruger-national-park-south-africa-image68361886.html?imageid=7C5898AA-9B45-4447-98EF-CB92AEA025CF&p=196821&pn=1&searchId=81afea0714a7b7094a750bf43216e26d&searchtype=0).

The following show how different the conspicuousness of the ear pinnae can be in R. campestris, depending on direction of illumination and whether the pale hair-curtains are open or closed (https://www.shutterstock.com/image-photo/steenbok-spotted-namibian-desert-710362444 vs https://stock.adobe.com/search?k=steenbok&asset_id=83926648).

Lähetetty 28. syyskuuta 2022 17:33 käyttäjältä milewski milewski | 30 kommenttia | Jätä kommentti

27. syyskuuta 2022

A new feature of adaptive colouration in ungulates: the fibular flag

@capracornelius @tandala @oviscanadensis_connerties @jeremygilmore @paradoxornithidae @beartracker @jacqueline_llerena @henrydelange @tonyrebelo @koosretief @justinhawthorne @ludwig_muller @happyasacupcake @marcelo_aranda @enricotosto96 @diegoalmendras @michaelweymann @jakob @jwidness @grinnin @karoopixie @davidbygott @dejong @gigilaidler @jason_van_den_berg @michalsloviak @nyoni-pete

Please see https://www.inaturalist.org/journal/milewski/70293-the-bambis-part-9-bleezes-flags-and-semets-in-the-bovid-genus-raphicerus#.

INTRODUCTION

Dear reader, here is a glimpse deep into the secret world of intraspecific communication in two
species of bambis.

Members of the antilopin genus Raphicerus are not gregarious. However, they tend to be monogamous.

Furthermore, adult females consort with their offspring, at least until weaning.

Therefore, there is frequent contact among individuals in the 'societies' of Raphicerus, despite the impression that these animals are 'solitary'.

Because bambis are small-bodied enough to hide for most of the time, their intraspecific communications tend to be secretive.

One way to monitor each other's whereabouts, as they forage in the mornings and evenings, is to 'flash' parts of the body that are small and low enough not to be noticed by scanning predators, but pale/bright enough to be conspicuous at fairly close range, at least when moved.

And this brings us to something that zoologists and naturalists may have overlooked.

It seems possible that grysboks (Raphicerus melanotis and Raphicerus sharpei) mediate such social monitoring, at least in part, by means of a certain part of the body that nobody has paid attention to: the inner surface of the hindleg, just above the hock (https://en.wikipedia.org/wiki/Hock_(anatomy)).

The pelage of the inner surface of the upper hindleg is oddly pale in these species.

Raphicerus melanotis:

http://cameratrap.mywild.co.za/p/cape-grysbok.html

https://www.inaturalist.org/observations/9522907

https://www.inaturalist.org/observations/26439871

https://www.inaturalist.org/observations/102342423

Raphicerus sharpei:

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=steenbok&order=relevance&safe_search=1&limit=100&search_page=3&search_type=pagination&get_facets=0&asset_id=478595701

https://stock.adobe.com/search?k=grysbok&asset_id=466446249

Scroll in https://africawild-forum.com/viewtopic.php?p=234341#p234341

By comparison, this same surface is not anomalously pale in the third member of the same genus, namely Raphicerus campestris.

The following show subspecies campestris of R. campestris, which coexists with R. melanotis but prefers more open vegetation (also see comment below for many more illustrations):

https://www.inaturalist.org/observations/107377965

https://www.inaturalist.org/observations/106332311

https://www.inaturalist.org/observations/50746594

https://www.inaturalist.org/observations/129193891

https://www.inaturalist.org/observations/122610678

https://www.alamy.com/stock-photo-steenbok-raphicerus-campestris-walking-in-shrubbery-south-africa-western-76154029.html?imageid=D54D52A6-FFDA-4FBE-9283-9390D08886ED&p=1142662&pn=1&searchId=b33750fe1700c0af1e7d56e14ee9b7da&searchtype=0https://es.123rf.com/photo_171698571_alert-steenbok-carnero-capturado-temprano-en-la-ma%C3%B1ana-en-el-parque-nacional-karoo-cabo-occidental.html?vti=n84f9ofebt93ncyyzk-1-81

The following shows that, in some individuals of R. campestris campestris, there is white on the inner, upper surface of the hindleg, but this does not extend to the vicinity of the hock: https://www.inaturalist.org/observations/60722940.

COINING A NEW TERM: 'FIBULAR FLAG'

In the context of adaptive colouration, a flag is defined as a relatively small-scale pattern that becomes conspicuous, at the scale of the whole figure, when activated by movement.

A typical location for flags, in ungulates, is the hindquarters, particularly the tail. And the functions of caudal flags include social and sexual signalling, and the announcement of anti-predator alarm to conspecifics, or the potential predators, or both.

What has been previously overlooked is that, in certain secretive species of ruminants with small tails, the location of flags on the posterior of the figure may have been shifted from the tail to another, more subtle and intriguing, location, namely the hind leg above the hock.

By far the most obvious candidate for a fibular flag is Alces alces (https://www.inaturalist.org/taxa/522193-Alces-alces).

In this large-bodied cervid, the tibial flag covers both the inner and the outer surfaces of the hindleg above the hock. It is individually and seasonally variable, and also depends on illumination.

ILLUSTRATIONS OF FIBULAR FLAG IN ALCES ALCES

https://www.inaturalist.org/observations/135414451

https://www.inaturalist.org/observations/115470987

https://www.inaturalist.org/observations/125843310

https://www.inaturalist.org/observations/121343112

https://www.inaturalist.org/observations/120257251

https://www.inaturalist.org/observations/129646111

https://www.inaturalist.org/observations/119626107

https://www.inaturalist.org/observations/119092478

https://www.inaturalist.org/observations/116521066

https://www.inaturalist.org/observations/134851345

https://www.inaturalist.org/observations/116789745

https://www.inaturalist.org/observations/135324468

https://www.alamy.com/stock-photo-moose-from-behind-142718462.html

https://www.inaturalist.org/observations/131879614

https://www.inaturalist.org/observations/126552983

https://www.inaturalist.org/observations/125993345

Why A. alces is unusual, in possessing a tibial flag, is worthy of further investigation.

However, for now let us return to our bambis, in which any tibial flag is far more subtle.

THINKING LATERALLY IN THE CASE OF RAPHICERUS

In Raphicerus, certain species/subspecies have more countershading (https://en.wikipedia.org/wiki/Countershading) than others.

This countershading is by definition located on the ventral parts of the figure, and the inner surfaces of the upper limbs.

However, on closer examination, there is a significant anomaly.

Countershading - which, by definition, works best when a bright sun is high in the sky- is best-developed in tropical and subtropical subspecies of Raphicerus campestris. It is least-developed in Raphicerus melanotis, which is restricted to the temperate zone

On this basis, one would expect the inner surface of the upper hind leg to be pale in R. campestris, vs not pale in R. melanotis.

However, in reality it is the opposite that is true. Raphicerus melanotis has a pale inner surface on the upper hindleg, whereas R. campestris tends not to have this.

Please scroll to the 11th photo in https://www.africawild-forum.com/viewtopic.php?t=527&start=20 for a particularly clear view of the tibial flag in Raphicerus sharpei.

The fibular flag in R. melanotis and R. sharpei is presumably activated when the animal walks, and it should be particularly visible in the oblique light of evenings and early mornings - when much of the foraging takes place.

The paleness, in R. melanotis, of the inner surface of the hind leg, is puzzling if interpreted simply from the viewpoint of countershading in aid of crypsis. This is because this part of the anatomy

  • is paler than the ventral surface of the torso, despite the fact that it
  • is not normally visible enough, in the standing figure, to need disguising.

I therefore tentatively suggest that this pale feature functions as a flag, during walking/asymmetrical standing in suitable illumination.

This fibular flag, I hypothesise, aids social monitoring by means of a signal low-profile enough to remain congruous with the furtive habits and overall inconspicuousness of the species concerned.

A similar rationale may possibly apply to an even smaller area of anomalously pale pelage in R. sharpei, which likewise transgresses countershading. This is located on the front surface where the foreleg joins the torso.

The anterior feature can perhaps be called an 'anterior axillary flag'.

https://www.flickr.com/photos/44691276@N06/8250863085

https://es.123rf.com/photo_110620408_sharpe-grysbok-in-kruger-national-park-south-africa-specie-raphicerus-sharpei-family-of-bovidae.html

https://www.alamy.com/stock-image-sharpes-grysbok-raphicerus-sharpei-male-adult-south-africa-mpumalanga-161763316.html?imageid=6332CFDE-0830-42B2-8ED6-8113A09A06AE&p=546796&pn=1&searchId=bb39c60edd2f811fc9c03d99a5112e0b&searchtype=0

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=steenbok&order=relevance&safe_search=1&limit=100&search_page=3&search_type=pagination&get_facets=0&asset_id=478595701)

Lähetetty 27. syyskuuta 2022 18:15 käyttäjältä milewski milewski | 16 kommenttia | Jätä kommentti

25. syyskuuta 2022

One of the few records of stotting in hippotragin bovids

@beartracker

Estes (1991), on page 116 of The Behavior Guide to African Mammals, states the following under the heading 'Postures and Locomotion' for the tribe Hippotragini (https://en.wikipedia.org/wiki/Grazing_antelope) of the family Bovidae:

"The trot is not a regular gait in this tribe but may appear as a transition between walk and gallop, and a STYLE-TROT is performed in situations of excitement or alarm. Oryxes have a particularly beautiful flowing trot with a suspension stage during which all feet are off the ground and the head is turned synchronously from side to side (Kingdon 1982). Trotting scimitar-horned oryxes hold their chins raised with horns back (Hugh 1980)."

What this means is that, in hippotragins, stotting (https://en.wikipedia.org/wiki/Stotting) takes the form of style-trotting.

In my experience, photos or videos capturing this form of anti-predator display are rare, even in the case of infants and juveniles in play.

Therefore, finding the following depiction today, I am posting it immediately, before it vanishes from the Web.

Please scroll to 24th photo in http://teamwindchase.com/Africa-2019-11.htm for style-trotting, a form of stotting, in Oryx gazella.

The following (https://www.youtube.com/watch?v=QL_OzqtuNxo) briefly shows trotting by an individual infant of Oryx dammah.

Lähetetty 25. syyskuuta 2022 22:42 käyttäjältä milewski milewski | 1 kommentti | Jätä kommentti

The bambis, part 9: bleezes, flags, and semets in the bovid genus Raphicerus

...continued from https://www.inaturalist.org/journal/milewski/70250-the-bambis-part-8-adaptive-colouration-in-grysboks-raphicerus-melanotis-and-raphicerus-sharpei#

Also see https://www.inaturalist.org/journal/milewski/70368-a-new-feature-of-adaptive-colouration-in-ungulates-the-tibial-flag#

Dear reader, please toggle between the two photos in https://www.inaturalist.org/observations/59156961. What do you notice, and what do you think the display means?

Now examine the following, which nicely shows the anti-predator context in which this display is deployed.

Are these individuals displaying their white buttocks to each other (as per the textbooks) or to the potential predator (in this case, the photographer, Tony Rebelo)?

The following is my interpretation of all of the various conspicuous features of colouration in the three spp. of Raphicerus (https://www.inaturalist.org/observations?place_id=any&taxon_id=42373&view=species).

BLEEZES (patterns of dark/pale colouration so conspicuous that they are obvious even when the figure is stationary, and even at a distance):

These are absent from all three spp. of Raphicerus (in contrast to e.g. Ourebia ourebi ourebi, https://www.inaturalist.org/journal/milewski/69937-adaptive-colouration-in-the-oribi-southern-forms-are-more-conspicuous-than-northern-forms#).

FLAGS (patterns of dark/pale colouration of moderate size, which become conspicuous only when activated by movement, of either a body part or the whole figure):

Auricular flags:

These are absent from all three spp. of Raphicerus (in contrast to e.g. Oreotragus saltatrixoides, https://www.inaturalist.org/journal/milewski/57595-the-bambis-part-4-a-new-species-of-klipspringer-in-southern-africa#).

Buttock flags:

A buttock flag is present in Raphicerus campestris, but absent from the other two spp.

The following show the buttock flag not activated:

https://stock.adobe.com/ro/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=steenbok&order=relevance&safe_search=1&limit=100&search_page=5&search_type=pagination&get_facets=0&asset_id=526322906

https://stock.adobe.com/ro/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=steenbok&order=relevance&safe_search=1&limit=100&search_page=5&search_type=pagination&get_facets=0&asset_id=516776123

https://stock.adobe.com/ro/search?k=steenbok&asset_id=96029539

https://stock.adobe.com/ro/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=steenbok&order=relevance&safe_search=1&limit=100&search_page=6&search_type=pagination&get_facets=0&asset_id=234422799

https://www.gettyimages.in/detail/photo/escaping-little-antelope-royalty-free-image/590583929?adppopup=true

scroll to 6th photo in http://visitcradock.co.za/mountain-zebra-national-park-cradock/#lightbox/5/

https://stock.adobe.com/ro/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=steenbok&order=relevance&safe_search=1&search_page=2&get_facets=0&search_type=pagination&asset_id=441156073

https://stock.adobe.com/ro/search?k=steenbok&asset_id=51231777

https://stock.adobe.com/ro/search?k=steenbok&asset_id=103481637

https://stock.adobe.com/ro/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=steenbok&order=relevance&safe_search=1&limit=100&search_page=3&search_type=pagination&get_facets=0&asset_id=121268962

https://stock.adobe.com/ro/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=steenbok&order=relevance&safe_search=1&limit=100&search_page=7&search_type=pagination&get_facets=0&asset_id=75206813

https://www.shutterstock.com/image-photo/close-photo-small-buck-called-steenbok-2008884197

https://www.shutterstock.com/image-photo/steenbok-standing-alert-kruger-national-park-1953181489

https://stock.adobe.com/ro/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_collectn%5D=0&filters%5Bcontent_type%3Aimage%5D=1&k=steenbok&order=relevance&safe_search=1&limit=100&search_page=6&search_type=pagination&get_facets=0&asset_id=426829025

The following show the buttock flag activated, while the figure is stationary in mild/initial alarm:

https://stock.adobe.com/ro/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=steenbok&order=relevance&safe_search=1&limit=100&search_page=6&search_type=pagination&get_facets=0&asset_id=180230559

https://stock.adobe.com/ro/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=steenbok&order=relevance&safe_search=1&limit=100&search_page=7&search_type=pagination&get_facets=0&asset_id=180230715

https://stock.adobe.com/ro/search?k=steenbok&asset_id=7826589

https://stock.adobe.com/ro/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=steenbok&order=relevance&safe_search=1&search_page=2&get_facets=0&search_type=pagination&asset_id=441230341

https://stock.adobe.com/ro/search?k=steenbok&asset_id=404356409

https://southafrica.co.za/how-to-identify-steenbok.html

https://stock.adobe.com/ro/search?k=steenbok&asset_id=526997849

https://stock.adobe.com/ro/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=steenbok&order=relevance&safe_search=1&search_page=2&get_facets=0&search_type=pagination&asset_id=322753486

https://stock.adobe.com/ro/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=steenbok&order=relevance&safe_search=1&limit=100&search_page=6&search_type=pagination&get_facets=0&asset_id=186548226

https://stock.adobe.com/ro/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=steenbok&order=relevance&safe_search=1&limit=100&search_page=7&search_type=pagination&get_facets=0&asset_id=239510784

https://stock.adobe.com/ro/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=steenbok&order=relevance&safe_search=1&limit=100&search_page=8&search_type=pagination&get_facets=0&asset_id=240700963

https://www.shutterstock.com/image-photo/cute-steenbok-on-alert-front-tree-1890922669

https://www.shutterstock.com/image-photo/steenbok-aphicerus-campestris-smallest-antelope-southern-1214048647

https://www.shutterstock.com/image-photo/steenbok-bush-south-africa-1302941758

https://www.inaturalist.org/observations/85907385)

The following show the buttock flag activated, while fleeing:

https://www.inaturalist.org/observations/115766655

https://www.inaturalist.org/observations/13490802

https://stock.adobe.com/ro/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=steenbok&order=relevance&safe_search=1&limit=100&search_page=4&search_type=pagination&get_facets=0&asset_id=466446514

https://www.cimicorp.com/DI/Collection29/slides/Africa_20081101_103818_926_2X.html

https://www.shutterstock.com/image-photo/steenbuck-raphicerus-campestris-running-over-dirt-1126962635

https://www.inaturalist.org/observations/111775121

https://www.inaturalist.org/observations/71315273)

https://www.inaturalist.org/observations/73647662

Tibial flags:

Please see https://www.inaturalist.org/journal/milewski/70368-a-new-feature-of-adaptive-colouration-in-ungulates-the-tibial-flag#.

Pedal flags:

A pedal flag is present in some subspecies/individuals of Raphicerus sharpei (see https://www.inaturalist.org/journal/milewski/70250-the-bambis-part-8-adaptive-colouration-in-grysboks-raphicerus-melanotis-and-raphicerus-sharpei#)

It is possibly also present in some individuals of R. campestris:

https://www.shutterstock.com/image-photo/sreenbok-antelope-kruger-national-park-south-47160058

https://www.shutterstock.com/image-photo/steenbuck-622472594

https://www.gettyimages.com.au/detail/photo/side-view-of-deer-standing-on-field-royalty-free-image/1396349874

https://www.pexels.com/photo/a-steenbok-in-the-wild-7057626/

Caudal flags:

These are absent from all three spp., the tails of which are small and plain-coloured.

SEMETS (patterns of relatively dark/relatively pale colouration of small size, conspicuous only at close range, and only when activated by movement of the body part concerned)

Auricular semets (see e.g. https://www.inaturalist.org/journal/milewski/55694-ten-best-illustrations-of-auricular-semets-in-deer#):

These are absent from all three spp.

Buccal semets:

A buccal semet is possibly present in all three spp., consisting of

  • the darkness of the rhinarium, the rostrum adjacent to the rhinarium, and the bare edge of the lower lip, vs
  • the paleness of the pelage of the lips and, to various extents, the sides of the mandibles.

This buccal semet is, in human eyes, clearest in Raphicerus campestris:

https://www.inaturalist.org/photos/8333

https://www.shutterstock.com/image-photo/steenbok-aka-steinbuck-steinbok-male-140509621

https://www.inaturalist.org/observations/80251823

https://www.alamy.com/steenbok-raphicerus-campestris-young-male-portrait-south-africa-mpumalanga-kruger-national-park-image345028232.html?imageid=7C5917E7-A9ED-4B1B-B500-0DB8D4366C4B&p=853442&pn=1&searchId=18a1c61216ed6fd2c4b1d370fb8cd884&searchtype=0

https://www.alamy.com/steenbok-raphicerus-campestris-male-portrait-south-africa-mpumalanga-kruger-national-park-image345028364.html?imageid=DFDD0021-A370-4B2C-9C81-EB338FDB72D7&p=853442&pn=1&searchId=18a1c61216ed6fd2c4b1d370fb8cd884&searchtype=0

https://www.shutterstock.com/image-photo/steenbok-aka-steinbuck-steinbok-female-140509576

https://www.shutterstock.com/image-photo/steenbok-raphicerus-campestris-relaxed-resting-lying-785515177

https://www.inaturalist.org/observations/90699392

https://stock.adobe.com/ro/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=steenbok&order=relevance&safe_search=1&limit=100&search_page=5&search_type=pagination&get_facets=0&asset_id=396572092

https://stock.adobe.com/ro/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=steenbok&order=relevance&safe_search=1&limit=100&search_page=5&search_type=pagination&get_facets=0&asset_id=396572147

It is least clear in Raphicerus melanotis:

see https://www.inaturalist.org/journal/milewski/70250-the-bambis-part-8-adaptive-colouration-in-grysboks-raphicerus-melanotis-and-raphicerus-sharpei#.

DISCUSSION

The following is typical of the social setting in which the buccal semet hypothetically functions: https://www.shutterstock.com/image-photo/steenbok-raphicerus-campestris-relaxed-resting-lying-785515171.

Pedal flags are poorly-developed in all spp. of Raphicerus, in contrast to certain coexisting species/subspecies such as Sylvicapra grimmia caffra (https://stock.adobe.com/ro/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=steenbok&order=relevance&safe_search=1&limit=100&search_page=5&search_type=pagination&get_facets=0&asset_id=362016670).

The main feature of adaptively conspicuous colouration in Raphicerus is the buttock flag of R. campestris (https://www.inaturalist.org/observations/126223294).

However, even this feature is subtle, in keeping with the emphasis on hiding from predators, wherever possible, in these diminutive ruminants.

This buttock flag is phylogenetically related to bleezes on the buttocks of gazelles (e.g. Nanger granti, https://upload.wikimedia.org/wikipedia/commons/c/cb/Nanger_granti.jpg). In both Gazella and R. campestris, the pelage on the buttocks can be flared by piloerection, to enhance conspicuousness.

However, the buttock flag of R. campestris differs in at least three ways from those of gazelles, viz.

The following show the shift in the shape of the back, from

The following show the boosting in the conspicuousness of the white of the buttocks as the posture changes from unalarmed (https://www.shutterstock.com/image-photo/steenbok-aka-steinbuck-steinbok-male-140509591) to mildly/initially alarmed (https://www.inaturalist.org/observations/132963728 and https://www.shutterstock.com/image-photo/steenbok-standing-frozen-scared-13160773 and https://www.inaturalist.org/observations/118911269).

The following suggests that, as long as the hindquarters remain hunched, the buttock flag can hardly be displayed: https://www.shutterstock.com/image-photo/small-antelope-called-steenbok-enjoying-spring-42206143. What is needed is at least the posture shown in: https://www.shutterstock.com/image-photo/steenbok-raphicerus-campestris-kalahari-injury-on-80500765.

Lähetetty 25. syyskuuta 2022 22:15 käyttäjältä milewski milewski | 25 kommenttia | Jätä kommentti

23. syyskuuta 2022

The bambis, part 8: adaptive colouration in grysboks, Raphicerus melanotis and Raphicerus sharpei

@capracornelius @tandala @oviscanadensis_connerties @jeremygilmore @paradoxornithidae @beartracker @jacqueline_llerena @henrydelange @tonyrebelo @koosretief @justinhawthorne @ludwig_muller @happyasacupcake @marcelo_aranda @enricotosto96 @diegoalmendras @michaelweymann @fionahellmann

...continued from https://www.inaturalist.org/journal/milewski/58139-the-bambis-part-7-why-do-certain-genera-show-tropical-hues#

Grysboks (Raphicerus melanotis https://es.123rf.com/photo_39925015_a-rare-cape-grysbok-antelope-raphicerus-melanotis-south-africa.html and https://www.inaturalist.org/observations/72612861) and Raphicerus sharpei (https://www.shutterstock.com/image-photo/sharpes-grysbok-antelope-794728726 and https://www.alamy.com/stock-photo-sharpes-grysbok-31791328.html?imageid=8258088A-BE1C-47D2-B568-B4E03D47F25D&p=34420&pn=1&searchId=bb39c60edd2f811fc9c03d99a5112e0b&searchtype=0 and https://www.shutterstock.com/image-photo/sharpes-grysbok-hiding-thick-green-undergrowth-2178590039) occur in the southern and southeastern parts of Africa.

Among all the ungulates of the world, these are among the best examples of thoroughly inconspicuous colouration, of a cryptic type (https://en.wikipedia.org/wiki/Crypsis).

Grysboks are nocturnal and non-gregarious, and depend on shrubby vegetation for cover.

This means that the colouration is so plain and featureless that the figures blend extremely well into the environment (https://www.inaturalist.org/observations/11178739 and https://www.inaturalist.org/observations/48569125 and https://commons.wikimedia.org/wiki/File:Sharpe%27s_Grysbok.jpg and https://www.shutterstock.com/image-photo/sharps-grysbok-kruger-1083039092).

Even more so, when one considers that any differentiation in hues (rufous ground-colour vs grey on the posterior surface of the ears, https://www.inaturalist.org/observations/68999756) are probably invisible in the eyes of the relevant animals (i.e. grysboks themselves, and the Carnivora that are their main predators).

On one hand, this seems to make grysboks the simplest - and least interesting - of ungulates for further investigation, in terms of adaptive colouration.

However, I take a more curious approach.

What the simplicity of the colouration of grysboks means is that we have an opportunity to clarify any small-scale features that do not conform to the overall plainness.

These anomalous features (*asterisk indicates individual variation) are

BODY

Many species of mammals have grizzled/speckled pelage, in which each hair is graduated in colour from the base to the tip (https://en.wikipedia.org/wiki/Fur#/media/File:Down_Awn_and_guard_hairs_of_cat_2012_11_13_9203r.JPG).

However, in grysboks the form of grizzing is, as far as I know, unique among ruminants. This is because each hair is homogeneous in colour, but a minor percentage of the hairs are whitish.

Countershading (https://en.wikipedia.org/wiki/Countershading) is better-developed in R. sharpei than in R. melanotis. This is unsurprising, based on similar latitudinal patterns in various other ruminants (https://www.inaturalist.org/journal/milewski/53696-a-succinct-photo-guide-to-subspecies-of-the-bush-duiker#).

FACE, HEAD and EARS

The face of grysboks is not plain-coloured. One of the best illustrations of the pattern can be found by scrolling in https://www.edwardselfephotosafaris.com/newsp27.html.

All ruminants with a bare rhinarium have the nose dark-pigmented. However, the following of Cephalophus shows that the colouration of the face can otherwise be plain in small-bodied ruminants: https://www.dreamstime.com/stock-photo-duiker-close-up-detail-small-west-african-antelope-image75691614.

My interpretation is as follows:

The various markings on the face have dual functions at different scales.

When viewed from some distance, they amount collectively to a form of disruptive colouration, 'camouflaging' the head by disrupting its shape.

However, the same markings can also function, at close range, for social communication, e.g. aiding individual recognition.

Grysboks differ from their congener, Raphicerus campestris, in that the whitish pelage adjacent to the eye (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=steenbok&order=relevance&safe_search=1&limit=100&search_page=2&get_facets=0&search_type=pagination&asset_id=333179556) has been eclipsed.

I suspect that this has occurred not by means of any darkening of the hairs, but rather by a thinning of the pelage, exposing the blackish skin (https://www.redbubble.com/people/mags/works/7400304-the-tiny-shy-scarce-sharpe-s-grysbok-raphicerus-sharpei-kruger-national-park).

The ear pinna is large in all spp. of Raphicerus, probably for thermoregulation as much as hearing.

However, it is puzzling that the hair-curtains, which open and close ostensibly in reaction to temperature, are not a brownish colour, which would make the front-of-ear inconspicuously plain.

Instead, the hair-curtains are pale enough to be conspicuous at distances potentially relevant to scanning predators (https://www.inaturalist.org/observations/21208569 and https://www.inaturalist.org/observations/7026104).

This puzzle deserves further thought, as does the individually variable paleness on the front of the neck.

The following show the pale hair-curtains on front-of-ear

The paleness of the lower lip and chin is poorly explained by countershading.

I interpret the colouration around the mouth in both spp. to be a buccal semet (https://www.inaturalist.org/observations/11263147 and https://www.alamy.com/sharpes-grysbok-raphicerus-sharpei-south-africa-mpumalanga-kruger-national-park-image255383147.html?imageid=B2DB3495-B84D-45B8-93F0-CADC61B7296C&p=853443&pn=1&searchId=bb39c60edd2f811fc9c03d99a5112e0b&searchtype=0 and https://www.alamy.com/stock-photo-portrait-of-sharpes-grysbok-raphicerus-sharpei-in-the-bush-the-photo-33096574.html?imageid=097746CA-48F5-40A6-8578-BFE7EBA82631&p=60598&pn=1&searchId=bb39c60edd2f811fc9c03d99a5112e0b&searchtype=0). Please note, in the following view (https://www.inaturalist.org/observations/13582069), that the lower lip and adjacent pelage is the only part of the figure that is whitish.

This small-scale pattern may possibly be more conspicuous in ultraviolet than in the range of wavelengths visible in human eyes.

FEET

The following is possibly the most unexpected of my findings in this Post.

Raphicerus sharpei, in at least some individuals, has anomalously pale feet, which possibly function as a pedal flag. I have, as yet, no explanation for why there is no such feature in either R. melanotis or R. campestris.

However, R. sharpei also happens to differ from R. melanotis in

So, what emerges is that one of the main differences between the two spp. of grysboks is in the feet, including their anatomy, colouration, and action in producing an audial and possibly visual signal in an anti-predator context.

to be continued in https://www.inaturalist.org/journal/milewski/70293-the-bambis-part-9-bleezes-flags-and-semets-in-the-bovid-genus-raphicerus#...

Lähetetty 23. syyskuuta 2022 21:37 käyttäjältä milewski milewski | 18 kommenttia | Jätä kommentti