milewski's Journal

Impalas (Aepyceros) are unusual among the relatively large-bodied (body mass 50 kg or more) ungulates of the world, in that the adult colouration is approximately present already at birth.

In other words, the colouration of the pelage in impalas is remarkably precocial.

However, not all features of colouration are equally well-developed in neonates.

The aim of this Post is to document and illustrate these chronological (ontogenetic) variations.

LATERAL FLAG:

This flag is undeveloped (i.e. present only in incipient form) in infants.

This means that the lateral flag is perhaps the least precocial of all the patterns described in this Post (https://www.mindenpictures.com/stock-photo-impala-aepyceros-melampus-mother-running-with-her-calf-following-naturephotography-image00630132.html and https://www.dreamstime.com/impala-lamb-masai-mara-national-reserve-young-aepyceros-melampus-kenya-image243636698 and https://www.offset.com/photos/an-impala-and-young-calf-aepyceros-melampus-on-the-edge-of-woodland-963170 and https://www.superstock.com/asset/impala-calf-baby-impala-antelope-wilderness-africa/6001-16208619 and https://www.inaturalist.org/observations/4425491 and https://www.africanflyingadventures.com/life-and-death-in-the-bush-impala/ and https://www.gettyimages.com.au/detail/photo/portrait-of-deer-standing-on-field-kruger-national-royalty-free-image/1425287723?adppopup=true).

ANTERIOR AURICULAR FLAG:

The anterior auricular flag of the impala is precocial. It is complete in infants, before the dark stripes on the buttocks appear (https://www.alamy.com/stock-photo-two-baby-impala-antelopes-in-the-african-bush-29057562.html and https://www.dreamstime.com/royalty-free-stock-photo-impala-antelope-lambs-two-small-aepyceros-melampus-lake-nakuru-national-park-kenya-image40154625).

PEDAL FLAG:

The pedal flag is peculiarly precocial. It is present in infants, despite the expectation that the metatarsal glands are relatively poorly-developed at birth.

https://www.inaturalist.org/observations/165329533

https://www.inaturalist.org/observations/142346786

https://www.inaturalist.org/observations/106255260

https://www.inaturalist.org/observations/9839721

https://www.inaturalist.org/observations/9356668

PATTERN ON BUTTOCKS:

The following nicely illustrates the point that the pattern on the buttocks is not precocial:

https://www.gettyimages.com.au/detail/photo/instinct-royalty-free-image/975807822?phrase=african+impala&adppopup=true
https://www.gettyimages.com.au/detail/photo/impala-female-with-lamb-urinating-royalty-free-image/57079600?phrase=african+impala&adppopup=true
https://www.gettyimages.com.au/detail/photo/impala-with-her-young-aepycaros-melampus-masai-mara-royalty-free-image/57255400?phrase=african+impala&adppopup=true
https://www.gettyimages.com.au/detail/photo/impalas-okavango-delta-botswana-royalty-free-image/1457505003?phrase=african+impala&adppopup=true
https://www.gettyimages.com.au/detail/photo/impalas-okavango-delta-botswana-royalty-free-image/1457504436?phrase=african+impala&adppopup=true

BUCCAL SEMET:

The buccal semet of impalas is so precocial that it is complete at birth (https://www.dreamstime.com/impala-antelope-wilderness-africa-image174751963).

...continued from https://www.inaturalist.org/journal/milewski/89191-bleezes-flags-and-semets-in-the-adaptive-colouration-of-impalas-aepyceros-part-1#

CAUDAL FLAGS:

Penicillate caudal flag:

The long white hairs of the tail of impalas are normally hidden, partly because they are folded and partly because the tail is tucked (https://www.gettyimages.com.au/detail/photo/leaping-impala-chobe-national-park-botswana-royalty-free-image/538630239?adppopup=true).

However, the long white hairs are exposed in several situations, viz.- when the tail is swished to shoo insects,

• during micturition and defecation, and
• by infants and juveniles during suckling.

In all these cases, the distal 'joint' on the tail is unfolded, extending the white tip, but the lateral hairs remain folded. This is what I call a 'penicillate' pattern.

The following, of Aepyceros petersi, show how piloerection transforms the appearance of the tail in impalas:

• lateral long white hairs folded: https://www.alamy.com/stock-photo-black-faced-impala-escaping-from-danger-in-etosha-48448053.html?imageid=DB0D45E2-F327-4934-9037-AFEA80D19A41&p=163524&pn=11&searchId=3171fbca0bc4b0c09555c7c4a4e262c7&searchtype=0, versus
• lateral long white hairs piloerected: https://www.alamy.com/impala-males-sparring-aepyceros-melampus-etosha-national-park-namibia-image426416705.html?imageid=68527F02-9D6F-45A1-999A-F65ED4D3975A&p=18640&pn=10&searchId=f88dac56b555417b6a06fa62b13fef50&searchtype=0

https://www.dreamstime.com/amber-black-white-coloring-adult-male-impala-its-curved-horns-pondering-distance-tarangire-national-image134936351

https://www.inaturalist.org/observations/11072572https://www.inaturalist.org/observations/500032

The following show that, in impalas, the tail is displayed by infants/juveniles during suckling:

https://www.gettyimages.com.au/detail/photo/impalas-female-with-young-suckling-maasai-mara-royalty-free-image/993497958?adppopup=true

https://www.inaturalist.org/observations/10506367

https://www.inaturalist.org/observations/10504079

https://www.inaturalist.org/observations/197703501

https://www.inaturalist.org/observations/197638270

https://www.inaturalist.org/observations/178549792

https://www.inaturalist.org/observations/169814268

https://www.offset.com/photos/impala-aepyceros-melampus-and-calf-masai-mara-national-park-kenya-1017898

https://www.dreamstime.com/stock-photo-two-impalas-mother-baby-tarangire-tanzania-africa-image98512874

Laterally-piloerected caudal flag:

The long white hairs are piloerected during masculine display.

In Aepyceros melampus, which possesses a relatively small tail with a jointed feather-tassel, this gives the tail a fan-like shape (https://www.dreamstime.com/male-impala-botswana-aepyceros-melampus-savuti-region-northern-africa-image190060019 and https://www.dreamstime.com/stock-photo-impala-male-bellowing-territorial-snorting-growling-roaring-exciting-his-harem-females-rutting-time-image84208595 and https://matirasafari.com/wp-content/uploads/2017/12/ME8A3771m.jpg).

In Aepyceros petersi, which possibly possesses a relatively large tail with a plume-tassel, the shape is fluffy rather than fan-like.

https://www.inaturalist.org/observations/197926724

https://www.inaturalist.org/observations/3431525

https://www.inaturalist.org/observations/6901419

https://www.inaturalist.org/observations/11238746

Vertically-piloerected caudal flag:

During kick-stotting, a shape reminiscent of a butcher's cleaver results from

• flexing of the distal 'joint' to a right-angle, and
• piloerection of the lateral long white hairs in a ventral, not lateral, orientation, so that the tracts on left and right sides of the tail converge into a blade-like surface.

https://www.alamy.com/impala-black-faced-aepyceros-melampus-jumping-high-etosha-national-park-namibia-africa-image440466092.html?imageid=50688ED7-5A71-4DC9-93F7-CB9731215001&p=2206959&pn=5&searchId=a128d0b9ff98444a3d95336675cd8ddb&searchtype=0

https://www.gettyimages.com.au/detail/photo/sprinting-impala-royalty-free-image/503017078?adppopup=true

https://www.inaturalist.org/observations/3739299

BUCCAL SEMET:

The complex pattern on the chin, mandibles, and lips is small-scale, but crisply-defined, individually consistent, and different from that in any other ungulate,

This hypothetically functions to accentuate

• the chewing movements of rumination (https://www.dreamstime.com/impala-group-resting-impala-aepyceros-melampus-female-group-resting-ruminating-long-green-savanna-grass-kruger-national-image136523174), including at night, and
• the nibbling movements of the 'chin' when one individual grooms the pelage of another, a behaviour particularly well-developed in the impala.

This hypothetically facilitates social monitoring and gregarious vigilance.

https://www.dreamstime.com/royalty-free-stock-images-impala-image13351309

https://www.inaturalist.org/observations/9634

https://www.dreamstime.com/stock-photography-impala-wildlife-background-africa-fun-nature-ewe-chews-open-mouth-creating-image-humor-as-seen-image35412872

https://www.dreamstime.com/portrait-cute-wild-young-male-impala-aepyceros-melampus-nature-reserve-mara-north-conservancy-kenya-wildlife-image132878721

https://www.inaturalist.org/observations/10945099

https://www.alamy.com/impala-aepyceros-melampus-males-grooming-each-other-masai-mara-game-reserve-kenya-image262977047.html?imageid=C51F55F6-CE52-442E-AA83-3FAB2C5685D1&p=269351&pn=10&searchId=f88dac56b555417b6a06fa62b13fef50&searchtype=0

https://www.dreamstime.com/impala-black-faced-aepyceros-melampus-petersi-vrouwtje-close-up-kop-namibie-female-head-namibia-image129027529

https://www.alamy.com/stock-photo-blacked-faced-impala-or-black-faced-impala-aepyceros-melampus-petersi-74749154.html?imageid=CD8484B4-2478-4391-95D2-922B44C90F13&p=183828&pn=2&searchId=1f5542e7213ab29c0373963d6ec132b5&searchtype=0

https://www.dreamstime.com/stock-photo-black-faced-impala-etosha-national-park-namibia-image-image90011717

https://www.dreamstime.com/female-impala-aepyceros-melampus-portrait-kruger-national-park-south-africa-female-impala-aepyceros-melampus-portrait-kruger-image270426491

https://www.dreamstime.com/female-impala-aepyceros-melampus-portrait-kruger-national-park-south-africa-female-impala-aepyceros-melampus-portrait-kruger-image270426509

https://www.dreamstime.com/female-impala-aepyceros-melampus-portrait-kruger-national-park-south-africa-female-impala-aepyceros-melampus-portrait-kruger-image269672636

https://www.dreamstime.com/female-impala-aepyceros-melampus-portrait-kruger-national-park-south-africa-female-impala-aepyceros-melampus-portrait-kruger-image269672639

https://www.dreamstime.com/female-impala-aepyceros-melampus-portrait-kruger-national-park-south-africa-female-impala-aepyceros-melampus-portrait-kruger-image270428736

https://www.dreamstime.com/common-impala-kruger-national-park-south-africa-three-red-billed-oxpecker-grooming-common-impala-kruger-national-park-south-image291301703

https://www.dreamstime.com/stock-photo-fighting-impalas-image12091830

https://www.dreamstime.com/stock-photo-small-herd-antilopes-tarangire-tanzania-africa-image98512881

?Gular semet:

There is a whitish patch at the crook-of-throat (https://www.dreamstime.com/stock-photo-impala-savanna-national-reserved-south-africa-kenya-image40584100 and https://www.inaturalist.org/observations/197961307 and https://www.alamy.com/stock-photo-black-faced-impala-portrait-of-careful-grazing-antelope-eating-tiny-52966912.html?imageid=6B3C7657-DF3E-4C77-8C06-E2909124802F&p=5021&pn=3&searchId=a5b956efd11b804f1481dd41761ad956&searchtype=0), which can be somewhat conspicuous in the limited context of masculine display, particularly roar-grunting (https://www.youtube.com/watch?v=IqzBw9EWhjU).

However, the case for a gular semet is weakened by the facts that

• the pale feature in question is individually variable, rather than sexually dimorphic, and
• females do not have noticeable vocalisations.

https://www.alamy.com/stock-photo-male-black-faced-impala-challenging-another-male-in-the-etosha-national-138416866.html?imageid=D3A1E078-4C32-42EE-AF5A-0E3ED604E3FB&p=298586&pn=7&searchId=ae880af1fd61c0455cbecb5723d2b621&searchtype=0

https://www.dreamstime.com/impala-savanna-national-reserved-south-africa-kenya-animal-habitat-wildlife-scene-nature-image175021430

https://walkthewilderness.net/animals-of-africa-dominant-impala-behavior/

https://www.alamy.com/impala-aepyceros-melampus-young-male-grooming-a-female-nakuru-national-park-kenya-africa-image262992215.html?imageid=64908F75-77ED-426C-A7BB-D4C5258DF1F9&p=215444&pn=12&searchId=7dc11c78361bd5df1ff35974e5ef97a8&searchtype=0

https://www.dreamstime.com/stock-photos-male-impala-flehman-responce-image15033143

https://www.dreamstime.com/royalty-free-stock-photo-impala-showing-flehman-responce-botswana-image15518765

DISCUSSION

The overall colouration of impalas is puzzling, because it conforms to neither crypsis nor camouflage (https://www.gettyimages.ie/detail/photo/impalas-in-south-africa-royalty-free-image/1187648715?phrase=impala+the+animal&adppopup=true and https://www.gettyimages.ie/detail/photo/impala-and-kudu-in-south-africa-royalty-free-image/1185776039?phrase=impala+the+animal&adppopup=true and https://www.gettyimages.com.au/detail/photo/giraffes-walking-to-the-forest-royalty-free-image/836319922?phrase=african+impala&adppopup=true).

A case could be made that the overall colouration of impalas functions as 'gregarious camouflage' (https://www.dreamstime.com/impala-aepyceros-melampus-impala-aepyceros-melampus-small-fast-antelope-african-savanna-tsavo-national-park-taita-hills-image111661427 and https://www.dreamstime.com/stock-image-herd-impala-aepyceros-melampus-image40133771 and https://www.dreamstime.com/herd-alert-female-impala-looking-camera-okavango-delta-botswana-herd-alert-female-impala-botswana-image129682758 and https://www.gettyimages.ie/detail/photo/herd-of-impalas-royalty-free-image/148092452?phrase=impala+the+animal&adppopup=true and https://www.gettyimages.com.au/detail/photo/herd-of-female-impala-botswana-africa-royalty-free-image/142025793?phrase=african+impala&adppopup=true and https://www.gettyimages.com.au/detail/photo/herd-of-impala-aepyceros-melampus-against-a-green-royalty-free-image/1313472400?phrase=african+impala&adppopup=true).

https://www.gettyimages.com.au/detail/photo/herd-of-impalas-in-wilderness-royalty-free-image/561426203?phrase=african+impala&adppopup=true and https://www.gettyimages.com.au/detail/photo/impalas-royalty-free-image/561426993?phrase=african+impala&adppopup=true and https://www.gettyimages.com.au/detail/photo/impala-herd-royalty-free-image/561427575?phrase=african+impala&adppopup=true

https://www.gettyimages.com.au/detail/news-photo/impala-aepyceros-melampus-herd-of-females-in-grass-alert-to-news-photo/578257132?adppopup=true

https://www.gettyimages.com.au/detail/photo/herd-of-impalas-and-plains-zebras-royalty-free-image/534980932?phrase=african+impala&adppopup=true

https://www.gettyimages.com.au/detail/photo/male-impalas-and-topi-royalty-free-image/519948262?phrase=african+impala&adppopup=true

The colouration on the back-of-ear of impalas is puzzling.

This because the blackish of the distal third (a broadly apical feature) does not achieve conspicuousness.

https://www.gettyimages.ie/detail/photo/high-angle-view-of-goats-walking-on-field-royalty-free-image/1306773451?phrase=impala+the+animal&adppopup=true

https://www.gettyimages.ie/detail/photo/herd-of-female-impala-in-serengeti-national-park-royalty-free-image/169566128?phrase=impala+the+animal&adppopup=true

There is an adaptive trend among the ruminants of the world, as follows.

Species adapted to dense cover tend to have

• inconspicuous colouration (particularly on the hindquarters),
• a halting gait, viz. the semi-crosswalk,
• a lack of stotting (strenuous displays of individual fitness, dissuasive to scanning predators), and
• non-gregarious society.

A typical example is bushbucks (Tragelaphus, https://www.inaturalist.org/taxa/1431867-Tragelaphus-sylvaticus and https://www.inaturalist.org/taxa/42341-Tragelaphus-scriptus).

By contrast, species adapted to short, sparse vegetation tend to have

• conspicuous colouration (particularly on the hindquarters),
• a smooth gait, viz. the amble,
• stotting, and
• gregarious society.

A typical example is the springbok (https://www.inaturalist.org/taxa/42283-Antidorcas-marsupialis).

Intermediate species show intermediate traits.

In the context of this adaptive axis, certain anomalies emerge. The following are prime examples.

Deer of genus Odocoileus in North and central America, and impalas (Aepyceros) in southern and East Africa, are comparable. Both fall into the intermediate part of the axis described above.

Both are associated with some woody cover, as opposed to treeless grassland. Accordingly, both are somewhat gregarious.

Both have

• medium body mass (about 50 kg),
• unremarkable body-proportions, and
• fairly nondescript colouration on forequarters and torso.

However, two incongruities emerge, as follows.

Firstly, Odocoileus deer combine

• a halting walking gait, linked to cover-dependence and non-gregariousness, with
• conspicuous colouration on the hindquarters, linked to open environments and gregariousness.

By contrast, impalas combine

• a smooth walking gait, linked to open environments and gregariousness, with
• inconspicuous colouration on the hindquarters, linked to cover-dependence and non-gregariousness.

Secondly, both genera have stotting displays. However, the gaits used are surprisingly different.

Odocoileus deer display by

• stiff-legged serial bouncing in the case of Odocoileus hemionus (https://www.youtube.com/watch?v=49fz_WKBrXo), accentuated by pale pelage on the rump,
• initial leaping in the case of Odocoileus virginianus, accentuated by pale pelage, activated on the tail and buttocks, and
• demonstrative walking/foot-stamping, in both spp. (https://www.youtube.com/watch?v=rmmpBklsfUY and 'alarm walking', https://academic.oup.com/jmammal/article/89/3/636/861999?login=false).

By contrast, impalas display by

• kick-stotting (apparently only in reaction to the African hunting dog, Lycaon pictus), in which the tail is displayed but not particularly conspicuously (https://www.youtube.com/shorts/Ul5PgndSuE8 and https://www.sciencephoto.com/media/953676/view/black-faced-impala-female-jumping and https://www.shutterstock.com/image-photo/impala-aepyceros-melampus-female-jumping-on-2322843111 and https://www.shutterstock.com/image-photo/three-jumping-impala-lambs-center-one-52838104 and https://www.shutterstock.com/image-photo/impala-athletics-585239423 and https://www.shutterstock.com/image-photo/dancing-impalas-on-move-537287350 and https://www.shutterstock.com/image-photo/impala-pronking-morning-light-on-serengeti-756579790 and https://www.shutterstock.com/image-photo/flying-impala-wild-1981885313 and https://www.shutterstock.com/image-illustration/young-impala-female-playing-jumping-green-681128110), and
• bounding, in which the tail is negligibly displayed (https://www.shutterstock.com/image-photo/jumping-impala-africa-1266703183 and https://www.gettyimages.com.au/detail/video/slow-motion-tracking-shot-profile-herd-of-impalas-stock-video-footage/89-59 and https://www.shutterstock.com/image-photo/impala-jumping-avoid-being-caught-greater-40298869 and https://www.shutterstock.com/image-photo/common-impala-kruger-national-park-south-1164360943).

Stating the puzzle concisely:
The deer referred to are incongruently demonstrative, whereas impalas are incongruently non-demonstrative.

Before attempting to explain this puzzle, let us examine the evidence by means of photos/video clips.

The following show the semi crosswalk, which is

• associated with cover-dependent ruminants, and
• in the case of Odocoileus has been 'exaggerated' into demonstrative walking.

What is remarkable is that a halting gait, allowing the animal to 'freeze' with two legs in the air in order to blend into the background when hearing or seeing something suspicious, has been converted from an adaptation for concealment to an adaptation for advertisement. This has been done not by changing the footfall-sequence, but by exaggerating the lifting/lowering of the feet into conspicuous movements, probably together with release of odour from the pedal glands.

https://www.pond5.com/stock-footage/item/234025607-slow-motion-panning-shot-horned-whitetail-deer-walking-dry-g

https://www.pond5.com/stock-footage/item/246892228-white-tail-deer-walking-ridge-whitetail-deer-rut

https://www.pond5.com/stock-footage/item/150433074-whitetail-deer-casually-walking-sand-dunes

https://www.pond5.com/stock-footage/item/168721004-young-whitetail-deer-walking-snow

https://en.wikipedia.org/wiki/White-tailed_deer

https://www.youtube.com/watch?v=zADVhWj51Vg

https://www.youtube.com/watch?v=0FcWHBhqKkU

https://www.youtube.com/watch?v=KHxu7QxHmL4

https://www.youtube.com/watch?v=sxq09JUPh5s

https://www.youtube.com/watch?v=rmmpBklsfUY

https://www.youtube.com/watch?v=8XRhlvmAMpk

https://www.youtube.com/watch?v=F9DLRNhuXI4

https://www.google.com.au/search?q=Deer+walking+video&sca_esv=891f019e1683b014&tbm=vid&prmd=visnmbtz&sxsrf=ACQVn0-G_0CAbk7Lb86HWwd4dTBeYH4Pog:1707263962886&ei=2sfCZYHjNYiOseMP4I2QsAQ&start=10&sa=N&ved=2ahUKEwiBuK7w9ZeEAxUIR2wGHeAGBEYQ8tMDegQIEhAE&biw=986&bih=537&dpr=2.7#fpstate=ive&vld=cid:020b8d7b,vid:_9UiYWLW3aw,st:0

https://www.google.com.au/search?q=Deer+walking+video&sca_esv=891f019e1683b014&tbm=vid&prmd=visnmbtz&sxsrf=ACQVn0-G_0CAbk7Lb86HWwd4dTBeYH4Pog:1707263962886&ei=2sfCZYHjNYiOseMP4I2QsAQ&start=10&sa=N&ved=2ahUKEwiBuK7w9ZeEAxUIR2wGHeAGBEYQ8tMDegQIEhAE&biw=986&bih=537&dpr=2.7#fpstate=ive&vld=cid:668720a6,vid:r3qAhrvKi5I,st:0

https://www.google.com.au/search?q=Whitetail+Deer+walking+video&sca_esv=891f019e1683b014&biw=986&bih=537&tbm=vid&sxsrf=ACQVn0-5EbkeMDOORd0LiIOy4cwaUaaWrw%3A1707265476343&ei=xM3CZdbJFOv6seMP7qi6-Ak&ved=0ahUKEwjWu4TC-5eEAxVrfWwGHW6UDp84FBDh1QMIDQ&uact=5&oq=Whitetail+Deer+walking+video&gs_lp=Eg1nd3Mtd2l6LXZpZGVvIhxXaGl0ZXRhaWwgRGVlciB3YWxraW5nIHZpZGVvMggQABiABBiiBDIIEAAYgAQYogQyCBAAGIkFGKIEMggQABiABBiiBEjeK1AAWOMccAB4AJABAJgBhwKgAYUSqgEFMC4xLjm4AQPIAQD4AQHCAgcQABiABBgNwgILEAAYgAQYigUYhgPCAgcQIxiwAhgnwgIIECEYoAEYwwTCAgoQIRgKGKABGMME&sclient=gws-wiz-video#fpstate=ive&vld=cid:fc7401aa,vid:sXdOEAV_2w4,st:0

https://www.youtube.com/watch?app=desktop&v=VX1_gswmoew

https://www.pond5.com/stock-footage/item/65151043-whitetail-buck-deer-velvet-walking-down-river

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10498029/

https://www.projectnoah.org/spottings/8321330

https://www.sciencedirect.com/science/article/abs/pii/S0376635718300214

https://psycnet.apa.org/record/2007-03630-013

https://www.researchgate.net/figure/Number-of-trials-where-stotting-behavior-was-present-or-absent-partitioned-by-vegetation_tbl2_46511766

https://wildaboututah.org/follow-the-bouncing-deer/

https://besjournals.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2656.2005.01014.x

https://www.pgmuseum.org/deer

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8372962/

https://www.jstor.org/stable/4535174

https://www.inaturalist.org/posts/76632-stotting-in-damaliscus

https://link.springer.com/article/10.1007/BF00299889

https://www.adfg.alaska.gov/index.cfm?adfg=wildlifenews.view_article&articles_id=915

https://www.nwf.org/en/Educational-Resources/Wildlife-Guide/Mammals/Mule-Deer

https://www.washington.edu/news/2019/02/27/return-of-the-wolves-how-deer-escape-tactics-help-save-their-lives/

https://psycnet.apa.org/record/2007-03630-013

https://www.taylorfrancis.com/books/edit/10.1201/9781003354628/ecology-management-black-tailed-mule-deer-north-america-james-heffelfinger-paul-krausman?refId=a138049a-857b-4c21-82d0-18be4e881ecf&context=ubx

https://academic.oup.com/jmammal/article/89/3/636/861999?login=false

https://onlinelibrary.wiley.com/doi/10.1111/j.1439-0310.2008.01530.x

https://www.etsy.com/listing/1609357643/royalty-free-reference-image-for-artists

https://n1outdoors.com/whitetail-vs-mule-deer-differences/

https://i0.wp.com/scvnews.com/wp-content/uploads/2014/02/mule-deer-stotting.pg_.jpg

https://www.quora.com/Whats-the-difference-between-the-Sitka-black-tailed-deer-from-the-Alaskan-pan-handle-and-the-white-tailed-deer-found-in-Pennsylvania

https://www.producer.com/news/sheep-researchers-ask-for-deer-poop-2/

https://punchmagazine.com/hop-skip-jump-nature-photography/

https://www.flickr.com/photos/scattered/4118787442

https://www.bear-tracker.com/fawns.html

https://www.dreamstime.com/stock-photo-stotting-mule-deer-doe-running-all-four-feet-off-ground-image98265009

https://bcgforums.com/threads/baby-day-at-the-bison-range-mule-deer-fawn-stotting-and-red-dog-bison-calf.27521/

https://www.dreamstime.com/stotting-north-west-white-tailed-deer-odocoileus-virginianus-i-stotting-north-west-white-tailed-deer-odocoileus-virginianus-image106299321

https://johncarroutdoors.com/2021/03/19/published-photo-in-just-released-book/

https://sideriusblog.com/2013/05/04/to-stot-or-not-to-stot-the-mule-deer/

https://www.facebook.com/USFWS/photos/a.419357095774/10159526086900775/

https://gf.nd.gov/magazine/2022/nov/running-without-interruption

https://www.flickr.com/photos/scattered/4118018035

http://blog.kootenay-lake.ca/?p=1379

https://www.flickr.com/photos/pageworld/51722599625

https://upload.wikimedia.org/wikipedia/commons/d/d4/Stotting_mule_deer.jpg

https://www.alamy.com/a-black-tailed-deer-stotting-across-a-winter-field-image235857060.html

https://www.oklahoman.com/story/lifestyle/2021/11/29/what-stotting-and-why-do-mule-deer-do-it-northwestern-oklahoma/8659222002/

https://www.youtube.com/watch?v=h8DweS5Z684

https://www.youtube.com/watch?v=v1_qLKWeXPA

https://www.youtube.com/watch?v=ls2lmrmSQzA

https://petereades.photoshelter.com/image/I0000PVbRWhF5uYM

https://petereades.photoshelter.com/image/I000021Up4Tkw3LI

https://www.facebook.com/watch/?v=3443767672325312

https://www.istockphoto.com/photo/prairie-deer-saskatchewan-gm1953479708-557358161?phrase=large+running+mule+deer&searchscope=image%2Cfilm

https://www.istockphoto.com/photo/black-tailed-mule-deer-odocoileus-hemionus-gm175224325-22633462?phrase=large+running+mule+deer&searchscope=image%2Cfilm

https://www.istockphoto.com/photo/run-away-buck-gm1568260104-527735356?phrase=large+running+mule+deer&searchscope=image%2Cfilm

https://www.istockphoto.com/photo/stag-deer-running-fast-across-dirt-road-gm1372645457-441704655?phrase=large+running+mule+deer&searchscope=image%2Cfilm

https://www.istockphoto.com/photo/mule-deer-in-yellow-stone-gm1750423086-543753423?phrase=large+running+mule+deer&searchscope=image%2Cfilm

https://www.istockphoto.com/photo/mule-deer-gm1467071727-498929924?phrase=large+running+mule+deer&searchscope=image%2Cfilm

https://www.istockphoto.com/photo/mule-deer-gm1923040417-555492590?phrase=large+running+mule+deer&searchscope=image%2Cfilm

https://www.istockphoto.com/photo/mule-deer-running-beside-harvested-field-in-montana-gm1297691491-390758660?phrase=large+running+mule+deer&searchscope=image%2Cfilm

https://www.istockphoto.com/photo/mule-deer-doe-jump-run-gm172356051-4067117?phrase=large+running+mule+deer&searchscope=image%2Cfilm

https://www.istockphoto.com/photo/young-buck-deer-in-central-montana-gm1361656244-433971994?phrase=large+running+mule+deer&searchscope=image%2Cfilm

https://www.istockphoto.com/photo/colorado-wildlife-wild-deer-on-the-high-plains-of-colorado-gm1290700025-386031443?phrase=large+running+mule+deer&searchscope=image%2Cfilm

https://www.istockphoto.com/photo/wild-deer-on-the-high-plains-of-colorado-gm899371734-248171354?phrase=large+running+mule+deer&searchscope=image%2Cfilm

https://www.shutterstock.com/image-photo/white-tailed-deer-bounding-away-when-1291198885

https://www.vecteezy.com/photo/6224656-mule-deer-buck-bounding-over-prairie

https://www.mediastorehouse.com.au/ardea-wildlife-pets-environment/white-tailed-deer-buck-doe-bounding-away-tails-5295599.html

https://today.uconn.edu/2023/05/white-tailed-deer-bones-give-a-glimpse-into-connecticuts-past-and-may-help-inform-a-more-sustainable-future/

https://www.nps.gov/media/photo/gallery-item.htm?id=a4a44719-d504-4102-9dcb-0f2f3959657c&gid=FB5B2EE4-1DD8-B71B-0B202AEC100D1101

https://www.startribune.com/how-i-got-this-photo-whitetail-doe-bounds-across-woodland-trail/284798231/

https://coloradooutdoorsmag.com/2015/03/18/a-quick-guide-to-differentiate-mule-deer-from-white-tailed-deer/

https://www.jstor.org/stable/3801180

https://www.sciencedirect.com/science/article/abs/pii/S0003347219302416

https://www.jstor.org/stable/3798942

There are tens of thousands of photos labelled as impalas (Aepyceros) on the Web.

I spent today trawling through them, with two search-images.

Firstly, I sought photos particularly illustrative of various features of adaptive colouration.

Secondly, I sought the valuable photos among those of other bovids mislabelled as impalas or in other ways - of which there are thousands in their own right. These photos have been effectively 'buried' in the electronic record, but here I bring some of them back out into the light.

The following shows the VERTICALLY-PILOERECTED CAUDAL FLAG in Aepyceros melampus. The shape formed by the white hairs of the tail is similar to that of a butcher's cleaver. Unlike other ruminants, A. melampus possesses not a tassel but instead a jointed feather-tassel. The joint defines the right-angle distally, and the metaphorical blade of the cleaver is formed by piloerection perpendicular to the lateral plane:
https://www.dreamstime.com/impala-aepyceros-melampus-tarangire-national-park-tanzania-image301986232

The following shows how completely the jointed feather-tassel of A. melampus can remain hidden (by a lack of piloerection), even when the tail is untucked:
https://www.dreamstime.com/young-impala-fawn-standing-its-head-turned-toward-camera-kruger-national-park-south-africa-aepyceros-melampus-image150292156

The following shows the PENICILLATE CAUDAL FLAG in Aepyceros melampus. The distal joint in the jointed feather-tassel is open, without any other piloerection. In this case, the behaviour being flagged is micturition in adult males:
https://www.dreamstime.com/stock-photo-male-impala-side-kruger-national-park-south-africa-image77200245
https://www.dreamstime.com/stock-photo-male-impala-side-kruger-national-park-south-africa-image77199044

The following show the CORONAL FLAG of Aepyceros melampus particularly clearly. A main point to note is that, although there is a definite pattern on the buttocks, it is the pallor (owing to sheen) on the posterior surface of the crown that renders the figures conspicuous:
https://www.dreamstime.com/impala-looking-out-danger-image183413992
https://www.dreamstime.com/impala-aepyceros-melampus-kruger-national-park-mpumalanga-south-africa-image135031275

The following show the PEDAL FLAG of Aepyceros melampus particularly clearly. A main point to note is that, although impalas have distinct, complex, and subtle colouration, it is the pallor on the pasterns that advertise the figures:
https://www.dreamstime.com/impala-aepyceros-melampus-mother-young-masai-mara-park-kenya-image196850640
https://www.dreamstime.com/male-common-impala-stands-sunny-riverbank-image274387907

https://www.dreamstime.com/stock-photo-male-impala-rear-view-oxpecker-its-back-kruger-park-image81883072

https://www.dreamstime.com/royalty-free-stock-images-impala-ram-image21409539

https://www.dreamstime.com/royalty-free-stock-photos-young-impala-image24382208

https://www.dreamstime.com/impala-antelopes-waterhole-kruger-national-park-aepyceros-melampus-south-africa-image288451164

https://www.inaturalist.org/journal/milewski/89312-annotated-photos-of-impalas-and-other-bovids-mislabelled-as-impalas-on-the-web#

Adaptive colouration:

https://www.inaturalist.org/posts/89191-bleezes-flags-and-semets-in-the-adaptive-colouration-of-impalas-aepyceros-part-1#

https://www.inaturalist.org/posts/89191-bleezes-flags-and-semets-in-the-adaptive-colouration-of-impalas-aepyceros-part-2#

https://www.inaturalist.org/posts/49665-the-peculiarly-complex-tail-of-the-impala-aepyceros-melampus-has-several-caudal-flags-but-no-ischial-flag#

https://www.inaturalist.org/journal/milewski/48831-why-does-the-colouration-of-the-gerenuk-litocranius-walleri-resemble-that-of-the-common-impala-aepyceros-melampus#

https://www.inaturalist.org/journal/milewski/49126-detailed-similarities-and-differences-in-the-colouration-of-gerenuk-litocranius-walleri-and-common-impala-aepyceros-melampus#

Locomotion and posture:

https://www.inaturalist.org/posts/49366-locomotory-and-postural-peculiarities-of-the-impala-part-1#

https://www.inaturalist.org/journal/milewski/67632-locomotory-and-postural-peculiarities-of-the-impala-part-2#

https://www.inaturalist.org/journal/milewski/67772-recent-confirmation-of-the-ability-of-the-african-savanna-buffalo-to-swim#

https://www.inaturalist.org/posts/67772-recent-confirmation-of-the-ability-of-the-african-savanna-buffalo-to-swim#activity_comment_d0627c85-085a-4fb1-b331-08b3fd21657f

Larynx:

https://www.inaturalist.org/posts/50157-the-peculiar-ordinariness-of-the-larynx-of-the-impala#

Comparison with springbok:

https://www.inaturalist.org/journal/milewski/51386-similarities-and-differences-impala-aepyceros-vs-springbok-antidorcas#

Overall nature:

https://www.inaturalist.org/journal/milewski/50236-what-makes-the-impala-aepyceros-melampus-tick-some-initial-thoughts#

@jandutoit @variani18 @nyoni-pete @tonyrebelo @jeremygilmore @matthewinabinett @botswanabugs @beartracker @simontonge @dejong @capracornelius @paradoxornithidae

Also see https://www.inaturalist.org/posts/49665-the-peculiarly-complex-tail-of-impalas-aepyceros-has-several-caudal-flags-but-no-ischial-flag#

TASK

https://www.gettyimages.com.au/detail/photo/impala-run-together-aepyceros-melampus-masai-mara-royalty-free-image/57255399?phrase=african+impala&adppopup=true
https://www.gettyimages.com.au/detail/photo/impala-herd-royalty-free-image/543976826?phrase=african+impala&adppopup=true

At first sight, impalas (Aepyceros) seem to be rather plain-coloured ruminants (https://www.inaturalist.org/observations/66064514 and https://www.dreamstime.com/closeup-impala-closeup-impala-scientific-name-aepyceros-melampus-swala-pala-swaheli-image-taken-safari-located-image200322382 and https://www.dreamstime.com/typical-male-impala-broadside-closeup-male-impala-scientific-name-aepyceros-melampus-swala-pala-swaheli-serengeti-image301832285).

Furthermore, colouration is remarkably similar between

• the sexes (https://www.gettyimages.com.au/detail/photo/impala-family-royalty-free-image/1391649390?adppopup=true and https://www.alamy.com/stock-image-a-male-female-and-baby-impala-aepyceros-melampus-pause-for-an-informal-164664217.html and https://www.gettyimages.com.au/detail/news-photo/schwarzfersenantilopenbock-mit-weibchen-im-abendlicht-imm-news-photo/645833321?adppopup=true), and
• infants and adults (https://www.inaturalist.org/observations/163901096 and https://www.gettyimages.com.au/detail/photo/impala-and-fawn-royalty-free-image/1216744628?adppopup=true).

However, there are several medium- to small-scale patterns, which function mainly to accentuate postures and movements in social and sexual interactions, intraspecifically.

Indeed, impalas may perhaps possess

• more flags (which has a particular meaning in the terminology of adaptive colouration) than any other ruminants, and
• one of the clearest examples of a buccal semet.

BLEEZES

There are no bleezes in impalas.

This can be illustrated by comparison with

• the springbok (Antidorcas marsupialis), which possesses a lateral bleeze (https://www.alamy.com/springbok-and-impala-at-watering-hole-in-etosha-national-park-namibia-image1936111.html?imageid=9F3EE547-CA7F-4C6D-A485-AF8526CDB57E&p=3663&pn=1&searchId=4dd898aca9c1f5238216f36748d13aa1&searchtype=0 and https://www.alamy.com/herd-of-springbok-antidorcas-marsupialis-single-impala-aepyceros-melampus-image5282436.html?imageid=0B527D9B-22F1-4864-B539-5CCD181A2CF9&p=69351&pn=1&searchId=4dd898aca9c1f5238216f36748d13aa1&searchtype=0 and https://www.alamy.com/impala-aepyceros-melampus-and-springbok-buck-standing-by-a-waterhole-image475377281.html?imageid=7072A59A-9F8D-416E-8930-FF8765FE4E62&p=59099&pn=1&searchId=4dd898aca9c1f5238216f36748d13aa1&searchtype=0 and https://www.alamy.com/stock-photo-four-black-faced-impalas-aepyceros-melampus-petersi-and-one-springbok-128615701.html?imageid=C3B40B92-6025-413B-9356-33269CFC0413&p=642197&pn=1&searchId=4dd898aca9c1f5238216f36748d13aa1&searchtype=0), and
• the bontebok (Damaliscus pygargus pygargus), which possesses an ischiopygal bleeze (https://www.dreamstime.com/bontebok-impala-botlierskop-reserve-south-africa-bontebok-botlierskop-private-game-reserve-mossel-bay-bontebok-image127611797).

LATERAL FLAG:

The lateral flag in impalas consists of a relatively pale, crisply-defined panel on the flanks, extending towards the scapula.

When the pelage of the torso is piloerected (typically in the early morning light), the back and upper flanks are darkened by an effect converse to sheen (https://www.dreamstime.com/african-impala-feeding-grasslands-savannah-south-africa-kruguer-national-park-very-fast-typical-antelope-image252124011 and https://www.sabisabi.com/discover/topics/impalas). This does not necessarily confer conspicuousness.

However, when the pelage of the torso is sleek in the heat of the day, the relatively pale panel on the flanks shows a sheen-effect in certain illuminations. This 'pallid flank-band' may possibly be conspicuous enough to qualify as a flag.

https://www.inaturalist.org/observations/143987159

https://www.inaturalist.org/observations/10937414

https://www.dreamstime.com/royalty-free-stock-image-grazing-impalas-image17951726

https://www.dreamstime.com/impala-aepyceros-melampus-impala-aepyceros-melampus-herd-drinking-waterhole-masai-mara-park-kenya-image175559272

https://www.inaturalist.org/observations/4877608

https://www.inaturalist.org/observations/1500408

https://vaido.aminus3.com/image/2019-08-08.html

https://www.dreamstime.com/stock-photo-impala-antelopes-kruger-national-park-image64547334

https://www.gettyimages.com.au/detail/photo/male-impalas-royalty-free-image/820285962?phrase=african+impala&adppopup=true

The lateral flag is unapparent in wet weather (https://www.gettyimages.com.au/detail/photo/impala_3015_ma-royalty-free-image/520064866?adppopup=true).

ANTERIOR AURICULAR FLAG:

The anterior surface of the ear pinnae of impalas has a pattern of dark and pale (actually nearly black-and-white, https://www.dreamstime.com/impala-black-faced-aepyceros-melampus-petersi-image129022782 and https://www.dreamstime.com/stock-photo-female-impala-portrait-taken-nairobi-national-park-kenya-photograph-taken-face-has-wonderfully-soft-bokeh-image84212780 and https://www.dreamstime.com/royalty-free-stock-images-impala-wildlife-background-africa-funny-nature-ewe-chews-open-mouth-creating-image-fun-humor-as-seen-image35306109 and https://www.dreamstime.com/royalty-free-stock-photography-impala-ewe-portrait-image10434177 and https://www.alamy.com/female-impala-in-the-wild-image241774765.html?imageid=D9D12AC3-1E7A-4A65-AF44-143AB6B8EC8B&p=566502&pn=1&searchId=4dd898aca9c1f5238216f36748d13aa1&searchtype=0).

This is small-scale enough that it potentially contributes to camouflage-colouration (https://upload.wikimedia.org/wikipedia/commons/a/a9/Impala_ewe_behind.jpg).

However, it is large-scale enough to draw attention to the animal when the ears/head are moved on an otherwise stationary figure, in direct illumination.

The following nicely shows the difference between a carnivore, in which the front-of-ear has cryptic colouration, and an impala:
https://www.dreamstime.com/lion-walking-front-herd-impalas-lion-walking-front-herd-impala-chobe-national-park-botswana-image99984947

https://www.inaturalist.org/observations/196171207

https://www.alamy.com/stock-photo-male-and-female-impala-aepyceros-melampus-kruger-national-park-south-44122171.html

https://www.alamy.com/impala-antelope-namibia-africa-safari-wildlife-image389173397.html?imageid=EA8B6637-5266-4FFD-8CF7-4EC6F189480A&p=836506&pn=8&searchId=a070cd5329fc32fad5b6e81e3528abb8&searchtype=0

https://www.dreamstime.com/lion-walking-front-herd-impalas-lion-walking-front-herd-impala-black-white-chobe-national-park-image99984945

https://www.dreamstime.com/lion-walking-front-herd-impalas-lion-walking-front-herd-impala-chobe-national-park-botswana-image99984934

https://www.dreamstime.com/impala-antelope-namibia-africa-safari-wildlife-family-aepyceros-melampus-caprivi-strip-game-park-nambwa-wilderness-image191497107

The bare skin on the front-of-ear is flesh-coloured, not pigmented (https://www.alamy.com/black-faced-impala-etosha-namibia-august-2018-image398762437.html?imageid=18595578-042F-473D-9E0C-595D8F785C3C&p=557829&pn=4&searchId=f9415a767c0642ef78c594ff67510d1a&searchtype=0).

POSTERIOR CORONAL FLAG:

This pattern is a function of sheen (possibly including ultraviolet), rather than depigmentation/pigmentation (https://www.dreamstime.com/impala-looking-out-danger-image183413992).

Please focus on the posterior surface of the crown of the head, plus the adjacent surfaces on the nape and the posterior of the ears:

• The posterior surface of the ear pinnae resembles the anterior surface in that the apex has dark, short pelage (https://www.inaturalist.org/observations/197638308).
• Most of the rest of the posterior surface is medium-tone, not white (https://www.dreamstime.com/stock-photo-red-billed-oxpecker-picking-parasites-impala%C3%A2%E2%82%AC%E2%84%A2s-ear-image53978260 and https://www.dreamstime.com/male-impala-chobe-national-park-botswana-aepyceros-melampus-northern-africa-image190341224 and https://www.shutterstock.com/image-photo/picture-beautiful-impala-antelope-behind-754645228).
• However, the dark apex of the back-of-ear is near enough to the sheen of the crown to produce some dark/pale contrast, accentuated by motion (https://www.dreamstime.com/lot-impala-antelopes-grass-landscape-kenyan-savanna-image148057442 and https://www.gettyimages.com.au/detail/photo/impala-tsavo-west-kenya-royalty-free-image/997672746?adppopup=true).

https://www.dreamstime.com/stock-image-impala-south-africa-s-image7623741

https://www.inaturalist.org/observations/155879893

https://www.inaturalist.org/observations/67574563

https://www.inaturalist.org/observations/91859769

https://www.inaturalist.org/observations/107525771

https://www.inaturalist.org/observations/172686553

https://www.inaturalist.org/observations/188096583

https://www.inaturalist.org/observations/174649718

https://www.inaturalist.org/observations/161370714

https://www.inaturalist.org/observations/152034681

https://www.inaturalist.org/observations/143987108

https://www.inaturalist.org/observations/127988480

https://www.inaturalist.org/observations/108123388

https://www.inaturalist.org/observations/124925975

https://www.inaturalist.org/observations/110006406

https://www.inaturalist.org/observations/105794590

https://www.inaturalist.org/observations/105452142

https://www.inaturalist.org/observations/98078027

https://www.inaturalist.org/observations/89832137

https://www.dreamstime.com/lot-impala-antelopes-grass-landscape-kenyan-savanna-image148056738

https://www.inaturalist.org/observations/7309291

https://www.inaturalist.org/observations/11069915

For comparison, the following show similar views but without the sheen-effect:

https://www.dreamstime.com/royalty-free-stock-photo-african-impala-image9762415 and https://www.gettyimages.com.au/detail/photo/impala-mirror-reflection-royalty-free-image/98539628?adppopup=true and https://www.alamy.com/stock-photo-impala-aepyceros-melampus-females-masai-mara-game-reserve-kenya-88607324.html?imageid=F45D9D4C-FD25-4313-A080-6C07567FD7C1&p=269351&pn=12&searchId=7dc11c78361bd5df1ff35974e5ef97a8&searchtype=0 and https://www.alamy.com/stock-photo-female-black-faced-impala-lined-up-to-drink-at-waterhole-92886401.html?imageid=23535364-258D-46C0-A328-BBD180DCCFD9&p=45259&pn=2&searchId=1f5542e7213ab29c0373963d6ec132b5&searchtype=0 and https://www.dreamstime.com/stock-photo-impala-antilopes-national-park-masai-mara-kenya-image72425093 and https://www.inaturalist.org/observations/34869308 and https://www.inaturalist.org/observations/11187976

PEDAL FLAG:

The pasterns (https://en.wikipedia.org/wiki/Pastern) are whitish, the pallor resulting from both depigmentation and sheen.

On the hindfeet, the metatarsal glands have dark tufts (https://www.dreamstime.com/stock-photo-impala-legs-mkuze-national-park-south-africa-image54790604 and https://www.shutterstock.com/image-photo/metatarsal-glands-on-impalas-back-legs-2337218443 and https://www.inaturalist.org/observations/845707). The fetlocks are dark at the positions of the (absent) false-hooves. On the hindfeet, this connects with the dark of the metatarsal tufts.

Furthermore, there is an individually variable tendency - particularly in juveniles - to dark emphasis on the anterior, distal surface of the metacarpals and the metatarsals (https://www.dreamstime.com/stock-images-puku-image28618764 and https://www.dreamstime.com/royalty-free-stock-photos-puku-grazing-image28618738).

The pedal flag is dependent on illumination, and conspicuous mainly owing to

• the whitish appearance of the pasterns, and
• the motion of the feet.

https://www.alamy.com/stock-photo-male-black-faced-impala-21848815.html?imageid=5AC181EF-09F2-4D60-BDF1-2A7081B3645C&p=16296&pn=2&searchId=1f5542e7213ab29c0373963d6ec132b5&searchtype=0

https://www.inaturalist.org/observations/845707

https://www.inaturalist.org/observations/149646826

https://www.inaturalist.org/observations/165329533

https://www.inaturalist.org/observations/142370555

https://www.inaturalist.org/observations/142346786

https://www.inaturalist.org/observations/142136628

https://www.inaturalist.org/observations/141892335

https://www.inaturalist.org/observations/132672095

https://www.inaturalist.org/observations/108844718

https://www.inaturalist.org/observations/106255260

https://www.inaturalist.org/observations/105527064

https://www.inaturalist.org/observations/101359100

https://www.inaturalist.org/observations/98197075

https://www.inaturalist.org/observations/73952189

https://www.inaturalist.org/observations/56613497

https://www.dreamstime.com/stock-photo-impala-antilopes-national-park-masai-mara-kenya-image72425258

https://www.inaturalist.org/observations/33839351

https://www.inaturalist.org/observations/10593664

https://www.inaturalist.org/observations/10525863

https://www.inaturalist.org/observations/9839721

https://www.inaturalist.org/observations/9356668

https://www.inaturalist.org/observations/8926845

https://www.inaturalist.org/observations/197879541

https://www.inaturalist.org/observations/197084898

https://www.inaturalist.org/observations/1380182

to be continued in https://www.inaturalist.org/journal/milewski/89674-bleezes-flags-and-semets-in-the-adaptive-colouration-of-impalas-aepyceros-part-2#...

Many ungulates have pale pelage, of various extents and shapes, on the buttocks (ischial surface, https://dictionary.cambridge.org/dictionary/english/ischial and https://www.merriam-webster.com/medical/ischial).

The following shows the location of the ischium, the posterior-most bone in the pelvic skeleton: https://afs.ca.uky.edu/livestock/dairy/skeletal

However, in this Post I exclude those cases in which the feature in question

• extends to the rump or haunches (e.g. Alcelaphus: https://www.inaturalist.org/observations/103888817 and https://www.inaturalist.org/observations/128384280 and https://www.inaturalist.org/observations/37492988),
• is less conspicuous than the tail (),
• is hidden posturally under normal circumstances (e.g. Raphicerus campestris: https://www.inaturalist.org/journal/milewski/70293-the-bambis-part-9-bleezes-flags-and-semets-in-the-bovid-genus-raphicerus), and
• is outweighed, in overall conspicuousness, by bold colouration elsewhere on the figure, including the tail (e.g. gazelles: https://internationalsportsman.com/blackbuck-antelope-small-in-stature-big-in-sport/ and https://www.naturepl.com/stock-photo-thomson-39-s-gazelle-eudorcas-thomsonii-female-and-calf-masai-mara-nature-image01622554.html and https://www.dreamstime.com/stock-photo-gazelle-thomson-to-eat-grass-masai-mara-national-park-kenya-image68396184).

In other words, I am particularly interested in those forms in which - at least in posteriolateral view - an ischial patch is the most conspicuous feature of colouration.

The following should serve for an approximate search-image: https://www.africaimagelibrary.com/-/galleries/east-africa/rwanda/-/medias/0253a725-2299-45bf-9a1e-8583be306b0a-defassa-waterbuck-kobus-ellipsiprymnus-defassa-akagera-natio.

The tail has particular potential as a complicating factor in the relative conspicuousness of the buttocks.

This is because the tail

• is more mobile than the buttocks, hence more conspicuous in motion (https://www.grida.no/resources/2553),
• can be raised and held high, defining the silhouette of the figure (https://www.inaturalist.org/observations/130903897 and https://www.inaturalist.org/posts/53340-differences-among-gazelles-in-the-structure-and-function-of-the-tail and https://www.inaturalist.org/journal/milewski/69548-caudal-flagging-in-thomson-s-gazelle-compared-with-the-goitered-gazelle),
• if dark in contrast to pale buttocks, can be the more noticeable component of the composite pattern, even when stationary (https://www.projectnoah.org/spottings/1877256002/fullscreen and https://www.dreamstime.com/thomsons-gazelle-eudorcas-thomsonii-thomsons-gazelle-eudorcas-thomsonii-single-adult-young-kenya-september-image161979710 and https://www.gettyimages.com.au/detail/photo/pampas-deer-royalty-free-image/664344424?phrase=pampas+deer&adppopup=true and https://www.gettyimages.com.au/detail/photo/pampas-deer-royalty-free-image/664343890?phrase=pampas+deer&adppopup=true and https://www.facebook.com/watch/?v=953730318399390),
• ..

Gazella arabicahttps://www.pixoto.com/images-photography/animals/other-mammals/arabian-gazelle--6523769179602944

Gazella bennettiihttps://www.alamy.com/wild-chinkara-gazella-bennettii-aka-indian-gazelle-in-grasslands-habitat-around-pune-maharashtra-india-image224965292.htmlhttps://www.shutterstock.com/image-photo/chinkara-gazella-bennettii-grasslands-2282460153https://www.shutterstock.com/image-photo/chinkara-gazella-bennettii-grasslands-2282490895

Gazella maricahttps://www.flickr.com/photos/mikebarth/23973307372https://arabsstock.com/en/photos/image-79510-al-reem-gazelle-animal-one-nature-reserves-united-arab-emirates https://www.dreamstime.com/group-gazelles-group-beautiful-young-sand-gazelles-gazella-marica-park-arabian-peninsula-image193473128

Hippotragus niger

https://www.sciencephoto.com/media/389584/view/sable-antelope
https://www.agefotostock.com/age/en/details-photo/female-sable-antelope-hippotragus-niger-in-natural-habitat-south-africa/ESY-032086305
https://www.inaturalist.org/observations/180600325
https://www.inaturalist.org/journal/milewski/88983-does-the-sable-antelope-hippotragus-niger-possess-a-bleeze-part-1#
https://www.inaturalist.org/posts/85930-does-the-sable-antelope-hippotragus-niger-possess-a-bleeze-part-2-sexual-and-ontogenetic-development-of-the-ischio-abdominal-pattern-in-the-southern-sable-antelope-h-n-niger#
https://www.inaturalist.org/journal/milewski/86047-does-the-sable-antelope-hippotragus-niger-possess-a-caudal-flag#

Kobus defassa

This is perhaps the clearest-cut example of an ischial flag, among all the ungulates. However, even in this case, there is a compromising consideration. This is that Kobus ellipsiprymnus, which is often considered a subspecies of K. defassa, has a categorically different pattern on the hindquarters. Furthermore, the whitish pelage extends ventrally on to the upper hindlegs.

https://www.sciencephoto.com/media/389729/view/defassa-waterbuck
https://www.shutterstock.com/image-photo/defassa-waterbuck-looks-back-across-masai-2059418618
scroll in http://www.wildlife-of-africa.com/animals/defassa-waterbuck.htm

Gazella bennettii
https://www.shutterstock.com/image-photo/chinkara-gazella-bennettii-grasslands-2282490895

Antilope cervicapra

https://www.mediastorehouse.com.au/nature-picture-library/yashpal-rathore/blackbuck-antelope-cervicapra-male-18204719.html
https://www.dreamstime.com/black-buck-kid-portrait-green-back-ground-bucks-resident-species-gujarat-india-found-many-places-big-groups-image184881130

Ourebia ourebi

https://www.inaturalist.org/posts/70005-are-there-two-species-of-oribi-ourebia-instead-of-one#
https://www.inaturalist.org/posts/69937-adaptive-colouration-in-the-oribi-southern-forms-are-more-conspicuous-than-northern-forms#
https://www.inaturalist.org/posts/70860-summary-of-my-recent-observations-diagnostically-pale-features-on-the-hindquarters-of-bovid-bambis-ourebia-raphicerus-and-madoqua#
https://colombia.inaturalist.org/journal/milewski/70050-the-three-main-types-of-oribi-ourebia-at-a-glance#

Aepyceros melampus

Bos javanicus

The banteng (Bos javanicus) is the only member of the subfamily Bovinae that possesses an ischial flag.

This feature is somewhat sexually dimorphic. It is most distinct in mature males.

https://www.inaturalist.org/observations/166493287
https://www.inaturalist.org/observations/188475028
https://www.inaturalist.org/observations/179248772
https://www.inaturalist.org/observations/168830554
https://www.inaturalist.org/observations/166493285
https://www.inaturalist.org/observations/7859523
https://alchetron.com/cdn/banteng-ef6798a3-9044-4050-a190-db88f0eaf39-resize-750.jpeg
https://upload.wikimedia.org/wikipedia/commons/4/42/Bos_javanicus_5zz.jpg
https://www.gettyimages.com.au/detail/photo/java-banteng-wild-indonesia-bull-royalty-free-image/489133307?phrase=bos+javanicus&adppopup=true
https://www.agefotostock.com/age/en/details-photo/banteng-bull-bos-javanicus-asia/AAM-AAES72728
https://es.123rf.com/photo_76667652_male-banteng-has-the-red-to-the-black.html
https://www.shutterstock.com/image-photo/banteng-red-bull-southeast-asia-wild-730951786
https://www.istockphoto.com/video/bull-gm486265041-38243228
https://www.mindenpictures.com/stock-photo-banteng-bos-javanicus-birmanicus-taman-negara-malaysia-naturephotography-image90409137.html
https://es.123rf.com/photo_66402226_closeup-of-a-banteng-rear-with-part-of-the-tail.html
https://upload.wikimedia.org/wikipedia/commons/1/13/Burgers%27_Zoo_%2820190622125153%29.jpg
https://upload.wikimedia.org/wikipedia/commons/e/e8/Bos_javanicus%2C_%28wild%29_Banteng_-Huai_Kha_Khaeng%2820536293581%29.jpg
https://upload.wikimedia.org/wikipedia/commons/e/e8/Bos_javanicus%2C_%28wild%29_Banteng_-Huai_Kha_Khaeng%2820536293581%29.jpg
https://www.shutterstock.com/image-photo/closeup-banteng-rear-part-tail-471392174
https://www.istockphoto.com/photo/bull-gm461789365-32203682?phrase=banteng&searchscope=image%2Cfilm
https://www.istockphoto.com/photo/portrait-of-a-tropical-light-asian-cow-grazes-on-green-grass-gm1189814258-337029238?phrase=banteng&searchscope=image%2Cfilm
https://www.istockphoto.com/photo/portrait-of-a-tropical-light-asian-cow-grazes-on-green-grass-gm1181277550-331257613?phrase=banteng&searchscope=image%2Cfilm
https://www.istockphoto.com/photo/a-male-banteng-feeding-on-the-field-near-a-tropical-lake-gm1159085204-316827479?phrase=banteng&searchscope=image%2Cfilm
https://www.istockphoto.com/photo/banteng-group-in-wildlife-gm658436422-120078179?phrase=banteng&searchscope=image%2Cfilm
https://www.istockphoto.com/video/young-baby-banteng-bos-javanicus-or-red-bull-is-a-type-of-wild-cattle-gm1520309065-524558232?searchscope=image%2Cfilm
https://www.istockphoto.com/video/herd-busy-grazing-banteng-bos-javanicus-gm1443459763-482423282?searchscope=image%2Cfilm
https://www.istockphoto.com/photo/wild-banteng-and-family-in-green-field-gm1496586778-519211273?phrase=banteng&searchscope=image%2Cfilm
https://www.istockphoto.com/video/herd-busy-grazing-banteng-bos-javanicus-gm1443459763-482423282
https://www.istockphoto.com/video/bull-boss-javanicus-thailand-gm1442918809-482083889
https://www.istockphoto.com/video/banteng-bos-javanicus-also-called-the-tembadau-in-southeast-asia-listed-as-gm1293658924-387982694
https://www.istockphoto.com/video/bull-gm1133774100-301031465
https://www.dreamstime.com/royalty-free-stock-photography-banteng-image1533467
https://www.dreamstime.com/stock-photo-javan-banteng-bos-javanicus-also-known-as-tembadau-image86181298
https://www.dreamstime.com/stock-photo-banteng-bos-javanicus-redbull-forest-thailand-image42394646
https://www.dreamstime.com/royalty-free-stock-photo-banteng-calf-tree-investigates-large-trunk-image32372545
https://www.dreamstime.com/royalty-free-stock-images-male-banteng-stepping-out-wood-adult-grass-water-image34039839
https://www.shutterstock.com/image-photo/banteng-bos-javanicus-red-bull-type-2194049625
https://www.shutterstock.com/image-photo/back-view-female-banteng-cow-showing-2216844237
https://www.dreamstime.com/royalty-free-stock-photos-banteng-red-bull-wild-cattle-which-used-as-working-animal-found-southeast-asia-such-as-thailand-image36166918
https://upload.wikimedia.org/wikipedia/commons/2/2a/COLLECTIE_TROPENMUSEUM_Een_bantengstier_op_stal_TMnr_10023821.jpg
https://www.alamy.com/banteng-bos-javanicus-image547828619.html
https://www.earth.com/endangered-species/bos-javanicus/
https://www.gettyimages.com.au/detail/news-photo/december-2022-north-rhine-westphalia-cologne-the-banteng-news-photo/1245866350?adppopup=true
https://www.gettyimages.com.au/detail/photo/banteng-or-red-bull-southeast-asia-wild-life-animal-royalty-free-image/1367459782?phrase=bos+javanicus&adppopup=true
https://fictionrulezforever.fandom.com/wiki/Banteng?file=Banteng_%28Male%29.jpg
https://maker-scratchpad-youtube.fandom.com/wiki/Javan_Banteng?file=Javan_Banteng.jpg
https://www.bigstockphoto.com/image-191971720/stock-photo-javan-banteng-%28bos-javanicus%29%2C-also-known-as-the-tembadau
https://www.instagram.com/bloodorigins/p/C1kNoTZOyYb/
https://zootografiando.blogspot.com/2011/09/banteng.html

Dama dama

DISCUSSION

I know of no ungulate in which the buttocks are the only part of the stationary figure with conspicuous colouration.

There is no species of ungulate in which the conspicuous colouration on the buttocks constitutes, in itself, a bleeze.

This is because a bleeze is, by definition, more conspicuous than a flag. The buttocks are

• a medium-size, not large, surface,
• hardly visible in full profile, and
• not as well-illuminated as the rump.

Bleezes on the hindquarters often include the buttocks, but are never restricted to the buttocks.

https://www.istockphoto.com/photo/white-tailed-deer-gm1180023691-330423556?phrase=white+tailed+deer+tail&searchscope=image%2Cfilm

The flag of Capreolus capreolus in winter pelage straddles the boundary between the buttocks and the rump (https://www.dreamstime.com/roe-deer-winter-scenery-roe-deer-winter-forest-scenery-image237055449 and https://www.shutterstock.com/image-photo/roe-deer-winter-1585340431).

Cervus elaphus exemplifies the same principle, differing only in detail.
https://www.alamy.com/male-red-deer-stag-in-old-forest-from-back-view-looking-aside-image355584145.html

In the case of Cervus nippon, the main part of the conspicuous feature is indeed on the buttocks, but there is a significant extension on to the base of a tail that is so short that a caudal flag is out of the question.
https://fishandhuntmaryland.com/articles/pursuit-sika-deer
https://www.bing.com/images/search?view=detailV2&ccid=GCxZg9PV&id=081BF38D6DFAFF42D916D52C9FD5D8A61A31ECC0&thid=OIP.GCxZg9PVcy6uGsfU0rQ8NAHaFK&mediaurl=https%3A%2F%2Fwww.wildlifeonline.me.uk%2Fassets%2Fugc%2Fimages%2Fsika_stag_speed.jpg&exph=845&expw=1212&q=sika+deer&simid=608050370566253003&form=IRPRST&ck=76A9FB41D31CB5D328E75D346DB99DB3&selectedindex=3&itb=0&ajaxhist=0&ajaxserp=0&vt=0&sim=11
https://bestpracticeguides.org.uk/deer-ecology/sika-deer/

https://www.gettyimages.ie/detail/photo/lioness-is-still-hunting-a-springbok-nxai-pan-royalty-free-image/130849132?adppopup=true

https://www.inaturalist.org/observations/173067861

https://www.dreamstime.com/namibia-etosha-national-park-giraffe-black-faced-impala-drinking-waterhole-date-image298333687

https://www.inaturalist.org/observations/39539255

https://www.gettyimages.com.au/detail/photo/cheetah-is-checking-the-menu-royalty-free-image/576417193?phrase=african+impala&adppopup=true

The domestic dog (Canis familiaris) possesses an ischial flag (https://www.facebook.com/awdri.com.au/photos/a.339435487132/10152520888147133/?type=3).

https://hoodline.com/2020/04/7-cuddly-canines-to-adopt-now-in-plano/
https://www.youtube.com/watch?v=mDyHM6-5iIU
https://www.youtube.com/watch?v=GF11t8SVYaw
https://www.youtube.com/watch?v=x2wuOY3ONdE
https://www.youtube.com/watch?v=_MpuSPhXa7M
https://www.youtube.com/watch?v=PSoiyK7N8KM

This feature, viz. a conspicuously pale, bilaterally symmetrical patch on the buttocks, is restricted to individuals - produced by perhaps more than 100 breeds as different as chihuahua and rottweiler - with the black-and-tan colouration.
https://www.shutterstock.com/image-photo/kelpie-puppy-dreaming-next-new-adventure-1176771838
This, in turn, implies that the real main ancestor of the domestic dog - which was not the wolf (Canis lupus) - also featured an ischial flag. This is because no extant wild species of Canis possesses this feature.

Given the above, it occurs to me that perhaps the domestic dog is the only member of the Carnivora on Earth that retains an ischial flag in the extant fauna.

Bold colouration on the buttocks is associated with prey animals, rather than predators.

More particularly, they are associated, among mammals, with certain ungulates such as gazelles.

Lynx rufus
https://www.flickr.com/photos/bobcatweather/6018355559

Lynx canadensis
https://www.alamy.com/canada-lynx-kitten-lynx-canadensis-walking-in-the-winter-snow-in-montana-usa-image371234360.html?imageid=427F479C-4E21-4E80-A765-99F14BA1BB04&p=359637&pn=1&searchId=88bd808e7e04286c70bcfbba03a37eac&searchtype=0
https://www.alamy.com/a-wild-canadian-lynx-felis-lynx-crossing-an-unplowed-rural-road-in-alberta-canada-image398126694.html?imageid=0CFBD8D8-5C2C-44EA-8E78-CA57555FCF7C&p=166893&pn=1&searchId=88bd808e7e04286c70bcfbba03a37eac&searchtype=0
https://www.alamy.com/stock-photo-a-canadian-lynx-walking-through-the-tall-grass-34041969.html?imageid=218875A8-3C22-4757-895B-15C3D08B1B7A&p=166893&pn=1&searchId=88bd808e7e04286c70bcfbba03a37eac&searchtype=0
https://www.alamy.com/view-of-a-lynx-walking-away-from-the-camera-image483319964.html?imageid=4C860C54-A9FD-41E8-8775-9F0F12D9418E&p=1403655&pn=1&searchId=88bd808e7e04286c70bcfbba03a37eac&searchtype=0
https://www.alamy.com/a-wild-lynx-cat-felis-lynx-canadensis-walking-through-the-deep-snow-in-rural-alberta-canada-image398126650.html?imageid=5D88DF38-0AD1-409A-BB1E-96B630FF8472&p=166893&pn=1&searchId=88bd808e7e04286c70bcfbba03a37eac&searchtype=0
https://www.alamy.com/view-of-a-lynx-walking-away-from-the-camera-image460434784.html?imageid=CCF2B7C9-F66F-4A80-AC0E-4C8CD2202013&p=410857&pn=1&searchId=88bd808e7e04286c70bcfbba03a37eac&searchtype=0
https://www.alamy.com/a-wild-lynx-cat-felis-lynx-canadensis-walking-through-the-deep-snow-in-rural-alberta-canada-image398126647.html?imageid=43CF579D-4699-4D05-89BD-DFF539FDFB67&p=166893&pn=1&searchId=88bd808e7e04286c70bcfbba03a37eac&searchtype=0
https://www.alamy.com/big-wild-lynx-cat-seen-walking-across-a-dirt-road-in-northern-canada-during-summer-time-looking-at-camera-in-natural-environment-background-image426381478.html?imageid=AE0171EB-D9A4-42BE-9C8C-633F2FC5F069&p=1446820&pn=1&searchId=88bd808e7e04286c70bcfbba03a37eac&searchtype=0
https://www.alamy.com/big-wild-lynx-cat-seen-walking-across-a-dirt-road-in-northern-canada-during-summer-time-long-legs-greenery-natural-environment-background-image426380570.html?imageid=74FB63E5-7B83-4918-BFA6-22539603A5B0&p=1446820&pn=1&searchId=88bd808e7e04286c70bcfbba03a37eac&searchtype=0