Has the post-withers mane-tuft of Hippotragus evolved in mimicry of oxpeckers (Buphagus)? part 1

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Here are introductory images: https://wall.alphacoders.com/big.php?i=1165392 and https://www.robertharding.com/preview/741-2722/roan-antelope-two-oxpeckers-busanga-plains-kafue-national/.

This is the anatomical location of the withers: https://horse-pros.com/5478/horse-anatomy-withers.

Hippotragus spp. (https://www.inaturalist.org/observations?place_id=any&taxon_id=42331&view=species) are attractive to oxpeckers (Buphagus spp., https://www.inaturalist.org/observations?place_id=any&taxon_id=46&view=species and https://www.youtube.com/watch?v=fhuRR9Sg6l4).

It is obvious that these birds often perch just posterior to the withers (https://www.inaturalist.org/observations/5538629 and https://www.inaturalist.org/observations/34841340 and https://www.inaturalist.org/observations/57000034 and https://www.inaturalist.org/observations/32316511 and https://www.inaturalist.org/photos/29361796 and https://www.inaturalist.org/observations/148842553 and https://www.inaturalist.org/observations/17943594 and https://www.tripadvisor.com/LocationPhotoDirectLink-g1966913-d4491602-i276786359-Chelinda_Lodge-Nyika_National_Park_Northern_Region.html and https://stock.adobe.com/images/antilope-rouanne-hippotragus-equinus/430052750?prev_url=detail).

However, here is something odd.

In the following of Hippotragus equinus, how many individuals are perching just posterior to the withers? (https://www.inaturalist.org/observations/188890271).

The answer is two. So, what is the third object?

The answer is: a special tuft of the mane, which seems to have evolved to attract oxpeckers - somewhat like a decoy on a pond attracting ducks - in this genus of hippotragin bovids.

Now, please closely examine the following (https://www.inaturalist.org/observations/67077421). What do you see: bird(s), or mane-tuft(s)?

How about the following (https://www.inaturalist.org/observations/34374918 and https://www.inaturalist.org/observations/1837040)?

HIPPOTRAGUS EQUINUS (https://stock.adobe.com/images/pferdeantilopen-in-der-ebene-des-chobe-national-parks-in-der-nahe-von-savuti-botswana/243454629?prev_url=detail)

The mane in H. equinus is

• similar in females and males, and
• extremely precocial (https://www.africaimagelibrary.com/-/galleries/west-africa/senegal/-/medias/38bfbf0c-2120-11e0-8287-8bc0e7630dc0-roan-antelope-hippotragus-equinus-reserve-de-bandia-senegal).

The post-withers mane-tuft grows so promptly that it rivals the horns in length in small juveniles (https://www.inaturalist.org/observations/17941075 and https://www.inaturalist.org/observations/6793163 and https://www.inaturalist.org/observations/6442592).

The following shows the post-withers mane-tuft from behind: https://www.alamy.com/stock-photo-african-roan-antelope-calf-hippotragus-equinus-149312880.html?imageid=9AE78C2E-6D4B-4344-B1CE-7CB589235CCA&p=172933&pn=1&searchId=5b7e805efde1b320f1fde4bd1bddb9a3&searchtype=0 and https://stock.adobe.com/images/antilope-rouanne-hippotragus-equinus/430052709?prev_url=detail.

The West African subspecies, Hippotragus equinus koba, is extralimital to one of the two spp. of oxpecker, namely Buphagus erythrorhynchus (https://en.wikipedia.org/wiki/Yellow-billed_oxpecker#/media/File:Buphagus_africanus_map.svg and https://en.wikipedia.org/wiki/Red-billed_oxpecker#/media/File:Buphagus_erythrorhynchus_map.svg).

In this subspecies, the post-withers mane-tuft may be hardly noticeable in adults (https://www.inaturalist.org/observations/34105019 and https://www.inaturalist.org/observations/29326406 and https://www.inaturalist.org/observations/25801218 and https://www.inaturalist.org/observations/98860520 and https://www.inaturalist.org/observations/16027979).

However, it remains present (https://www.inaturalist.org/observations/5280584 and https://www.inaturalist.org/observations/6443409 and https://www.inaturalist.org/observations/6562117 and https://www.inaturalist.org/observations/6183580).

HIPPOTRAGUS NIGER

Hippotragus niger also shows a post-withers mane-tuft (https://www.inaturalist.org/observations/7026088 and https://www.mediastorehouse.com/flpa/sable-antelope-hippotragus-niger-adult-male-6543329.html and https://www.inaturalist.org/observations/164414284 and https://www.inaturalist.org/observations/60429397).

The following (https://stock.adobe.com/images/rappenantilope/33673336?prev_url=detail) shows the size of the post-withers mane-tuft relative to Buphagus erythrorhynchus, the smaller-bodied of the two oxpeckers.

However, the feature in question is less discrete than in H. equinus.

This is mainly because, in H. niger, the mane is

• characteristically tousled over its whole length (https://www.alamy.com/a-powerful-side-profile-of-a-male-sable-antelope-with-oxpeckers-perched-on-its-back-with-a-natural-bush-and-plains-background-hwange-zimbabwe-image371224157.html and https://www.alamy.com/sable-antelope-hippotragus-niger-female-with-yellow-billed-oxpecker-buphagus-africanus-on-back-hwange-national-park-zimbabwe-october-2012-image262940283.html and https://www.shutterstock.com/image-photo/sable-antelope-oxpecker-bird-1103394965 and https://www.dreamstime.com/sable-antelope-hippotragus-niger-rappenantelope-botswana-africa-seldom-antelope-oxpeckers-back-botswana-africa-image132849289 and https://www.inaturalist.org/observations/143707556), and
• relatively contiguous, posterior to the withers (https://www.gettyimages.ae/detail/photo/sable-antelope-hwange-zimbabwe-royalty-free-image/94123092?adppopup=true and https://www.mindenpictures.com/stock-photo-sable-antelope-hippotragus-niger-with-red-billed-oxpecker-buphagus-naturephotography-image70008115.html and https://www.mediastorehouse.com/flpa/sable-antelope-hippotragus-niger-adult-male-6543623.html and https://www.carriegollergallery.com/shop-bonnie-block-photography-art/custom-creature-portrait-painting-from-your-photos-by-carrie-goller-free-shipping-lsp6h-xrydp-r3efr-k5l97-pwecr-5h4fp and https://www.bigstockphoto.com/image-229775464/stock-photo-sable-antelope-kruger-national-park-south-africa and https://www.inaturalist.org/observations/108545995).

ONTOGENY

In H. niger, as in H. equinus, the mane - including the tuft in question - is extremely precocial (https://stock.adobe.com/images/sable-antelope-portrait/45304064?prev_url=detail and https://stock.adobe.com/images/the-sable-antelope-hippotragus-niger/65016549?prev_url=detail).

Infants of H. niger:

https://www.alamy.com/sable-antelope-hippotragus-nigeryoung-calf-south-africa-image181670081.html?imageid=28EAE029-B0E3-42DA-BF33-817622ABF79C&p=738474&pn=7&searchId=2e53d2ed5b881c2af6863ceb6110b704&searchtype=0

https://www.inaturalist.org/observations/134842522

Juveniles of H. niger:

https://stock.adobe.com/images/sable-antelope/249830413?prev_url=detail and

https://stock.adobe.com/images/portrait-of-a-female-sable-antelope-hippotragus-niger-okapuka-ranch-namibia/641134322?prev_url=detail).

A noteworthy aspect of the development of the mane in H. niger is that

• after appearing in dark form in infants, it partially reverts to paler form in juveniles, and
• the post-withers section of the mane may be differentiated by pigmentation even when it does not form a distinct tuft (https://stock.adobe.com/images/one-sable-antelope-hippotragus-niger-walking-in-savanna-blue-sky/248840433?prev_url=detail and https://www.inaturalist.org/observations/4608441 and https://www.inaturalist.org/observations/11019005 and https://www.shutterstock.com/image-photo/sable-antelope-oxpecker-bird-1103394965 and https://dewetswild.com/2021/08/31/a-wonderful-encounter-with-sable-antelope/#jp-carousel-42148).

This differentiation by means of pigmentation, as opposed to an actual gap in the mane, may apply even to adult males (https://stock.adobe.com/images/small-group-of-mature-sable-antelope-on-a-farm-in-south-africa/143805504?prev_url=detail).

POSTURE

The post-withers mane-tuft (or dark pigmentation to the same effect) remains prominent despite the lowering of the neck in foraging.

The anatomical position thus potentially enhances the value of this feature in attracting oxpeckers.

This applies to both spp. of Hippotragus, as shown in the following:

• H. equinus: https://www.alamy.com/roan-antelope-hippotragus-equinus-herd-feeding-on-grassy-plain-kafue-image65793429.html and https://upload.wikimedia.org/wikipedia/commons/5/5d/Roan_Antilope_%28Hippotragus_equinus%29_male_grazing_..._%2830280893990%29.jpg and https://www.istockphoto.com/photo/roan-antelope-in-open-grassland-mokala-national-park-south-africa-gm1254201926-366512745?phrase=open+roan&searchscope=image%2Cfilm and https://www.inaturalist.org/observations/178322087 and https://www.inaturalist.org/observations/102235544 and https://es.123rf.com/photo_19601669_roan-antelope-grazing.html and scroll to seventh photo in https://birdingforpleasure.blogspot.com/2014/11/roan-antelope.html and https://www.inaturalist.org/observations/57000034 and https://www.alamy.com/roan-antelope-hippotragus-equinus-in-busanga-plains-kafue-national-park-image256687373.html?imageid=DBA2921C-018D-4A79-8C43-C1DC59966C6E&p=18997&pn=4&searchId=f4904b3f875d4b7dbcba6638b9b119cf&searchtype=0 and https://www.inaturalist.org/photos/251101426
• H. niger: https://www.inaturalist.org/observations/137784658 and https://www.flickr.com/photos/154131356@N07/51714863572/in/pool-wildlife_unlimited/ and https://www.inaturalist.org/observations/179336462 and https://www.alamy.com/solitary-sable-antelope-hippotragus-niger-bull-grazing-chobe-river-botswana-may-image263012286.html and https://www.alamy.com/close-up-portrait-of-male-sable-antelope-hippotragus-niger-grazing-on-green-grass-sable-antelope-inhabits-wooded-savannah-in-east-africa-south-of-image368313579.html and https://www.shutterstock.com/image-photo/female-sable-antelope-hippotragus-niger-grazing-666036946 and https://www.alamy.com/female-sable-antelope-hippotragus-niger-grazing-south-africa-image206887757.html and https://upload.wikimedia.org/wikipedia/commons/1/16/Sable_Antelope.jpg.

ADDITIONAL PHOTOS OF THE POST-WITHERS MANE-TUFT: HIPPOTRAGUS EQUINUS

https://www.robertharding.com/preview/741-2719/roan-antelope-busanga-plains-kafue-national-park-zambia/

https://www.dreamstime.com/stock-photo-roan-antelope-portrait-savanna-southern-africa-image75288830

second photo in https://www.inaturalist.org/observations/174496393

https://www.inaturalist.org/observations/173418588

https://www.inaturalist.org/observations/173418589

https://www.inaturalist.org/observations/34841465

https://www.inaturalist.org/observations/27642639

https://www.inaturalist.org/observations/25684392

https://www.inaturalist.org/observations/24195924

https://www.inaturalist.org/observations/124729794

https://www.inaturalist.org/observations/101392151

https://www.inaturalist.org/observations/59295257

https://www.inaturalist.org/observations/19417570

https://www.inaturalist.org/observations/19128427

https://www.inaturalist.org/observations/9355801

ADDITIONAL PHOTOS OF THE POST-WITHERS MANE-TUFT: HIPPOTRAGUS NIGER

https://www.inaturalist.org/observations/72397302

https://www.inaturalist.org/observations/42159995

https://www.mediastorehouse.com/ardea-wildlife-pets-environment/common-sable-antelope-male-female-1305709.html

https://www.gettyimages.ae/detail/photo/sable-antelope-royalty-free-image/622152400?adppopup=true

https://www.gettyimages.ae/detail/photo/sable-antelope-royalty-free-image/988024350?adppopup=true

https://www.dreamstime.com/sable-antelope-walking-plains-africa-herd-elephant-waterhole-background-hwange-national-park-zimbabwe-image131746669

https://www.krugerpark.co.za/africa_sable.html

https://howieswildlifeimages.files.wordpress.com/2017/03/20151014-d4s_4558.jpg

https://www.flickr.com/photos/154131356@N07/51715923933/in/pool-wildlife_unlimited/

https://www.flickr.com/photos/154131356@N07/51716323674/in/pool-wildlife_unlimited/

https://www.inaturalist.org/observations/187595353

https://www.inaturalist.org/observations/184871699

https://www.inaturalist.org/observations/183155583

https://www.inaturalist.org/observations/139965882

https://www.inaturalist.org/observations/133373188

https://www.inaturalist.org/observations/104347723

https://www.inaturalist.org/observations/21313316

https://www.inaturalist.org/observations/14355100

https://www.inaturalist.org/observations/164414284

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

https://www.inaturalist.org/observations/4608441

https://www.inaturalist.org/observations/107512367

https://www.inaturalist.org/observations/7026088

to be continued in https://www.inaturalist.org/journal/milewski/88098-has-the-post-withers-mane-tuft-of-hippotragus-evolved-in-mimicry-of-oxpeckers-buphagus-part-2#...

Publicado el 25 de diciembre de 2023 a las 06:29 AM por milewski