In the adaptive colouration of genus Damaliscus, is there a caudal flag?

@tonyrebelo @jeremygilmore @tandala @oviscanadensis_connerties @capracornelius @davidbygott @paradoxornithidae

A caudal flag is a conspicuous pattern of colouration on (and, additionally in some cases, adjacent to) the tail, which is activated by movement.

This is exemplified by

Whether a given species/subspecies qualifies as possessing a caudal flag depends, in part, on how conspicuous the colouration is on the rest of the figure. A given tail might qualify as a caudal flag on a plain-coloured animal. However, it might not qualify on an animal with overall colouration so conspicuous as to 'eclipse' even the moving tail.

The latter is perhaps exemplified by Antidorcas marsupialis (https://www.alamy.com/namibia-etosha-national-park-springbok-defecating-image457491377.html and https://www.inaturalist.org/journal/milewski/75660-the-springbok-antidorcas-marsupialis-seems-to-qualify-as-possessing-a-facial-flag-but-not-a-caudal-flag#).

GENUS DAMALISCUS IN GENERAL

All species/subspecies of Damaliscus have tails of moderate size, with the tail-tassel mainly blackish in tone.

The tail differs considerably in structure in the two clades within the genus, namely

  • pygargus/phillipsi, and
  • lunatus/korrigum/topi/jimela.

In the former, the tail-tassel is relatively large and bushy, whereas in the latter the tail-tassel is relatively small and two-dimensional (laterally flattened), leaving the tail-stalk relatively long.

The following are illustrative:

phillipsi:
https://willdlife.fandom.com/wiki/Blesbuck?file=Blesbok.jpg

lunatus lunatus:
https://stock.adobe.com/search?k=%22common+tsessebe%22&asset_id=284355340
https://www.dreamstime.com/royalty-free-stock-images-tsessebe-antelope-rare-damaliscus-lunatus-south-africa-image32399699
https://www.shutterstock.com/it/image-photo/common-tsessebe-bush-landscape-botswana-2144729843
https://www.shutterstock.com/it/image-photo/common-tsessebe-standing-meadow-sunlight-2144106859

topi:
https://www.pond5.com/stock-footage/item/171141159-pissing-coastal-topi-damaliscus-lunatus-highly-social-antelo

jimela
https://www.shutterstock.com/it/image-photo/african-male-topi-standing-alone-on-1480887302
https://www.dreamstime.com/topi-antelope-standing-hillocks-to-attract-his-mate-image189824089
https://www.dreamstime.com/male-topi-displays-himself-dirt-mound-image176022832
https://www.shutterstock.com/it/image-photo/topi-on-termite-mound-mara-national-1511326487
https://www.shutterstock.com/it/image-photo/topi-newborn-calf-masai-mara-1652939539
https://www.shutterstock.com/it/image-photo/urinating-topi-masai-mara-kenya-east-1191665062

This difference is visible already in infants, when the dark tone has yet to develop fully:

DAMALISCUS PYGARGUS PYGARGUS

The tail of the bontebok is large enough to be conspicuous, particularly because the white tail-stalk contrasts with the black tail-tassel (https://www.agefotostock.com/age/en/details-photo/bontebok-antelope/ESY-008277294/1). However, in terms of adaptive colouration, the tail is subsidiary to the ischiopygal bleeze, which is the more conspicuous feature (https://www.inaturalist.org/journal/milewski/76311-adaptive-colouration-in-the-bontebok-damaliscus-pygargus-pygargus-part-1-adults#).

The bontebok displays its tail in several social contexts (e.g. courtship, https://www.alamy.com/stock-photo-bontebok-blesbok-antelope-damaliscus-damaliscus-dorcas-bovidae-male-36820913.html?imageid=D177A04E-5BB2-42A8-8538-B839CCC540E6&p=26096&pn=5&searchId=78e3c36a9917c21e07efdd82f4c4fbc0&searchtype=0).

However, it has not been recorded to display the tail but in alarm or while fleeing.

It is difficult to assess the displaying of the tail in the context of predation, because the bontebok has never been observed reacting to non-human predators. Furthermore, it has seldom been observed to stot, although capable of doing so.

Estes (1993, page 118) mentions the following displays of the tail, in Damaliscus pygargus (including phillipsi):

"Territorial Advertising: Lowstretch, with tail curled up at high intensity (see Fig. 11.3). Herding and displaying to females"

"Submission: Head-low posture with tail curled up. Approaching with tail curled is response of intimidated blesbok to displaying male"

"Courtship: Lowstretch +/- tail curled up (see Fig. 11.3). Posture of territorial male approaching female. Male sniffs female's vulva. Female stands with tail out and ears back, then moves quickly away, wagging tail. Olfactory check of female's reproductive status"

The bontebok wags/swishes its tail only in reaction to insects, except for the social wagging described above.

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

In view of the above, does the bontebok qualify for a caudal flag?

This is ambivalent.

An argument can be made for a caudal flag in the bontebok in a social/sexual context. However, it cannot in the context of anti-predator displays.

DAMALISCUS PYGARGUS PHILLIPSI

The tail-tassel of the blesbok is

The darkness of the tail-tassel extends on to the dorsal (upper) surface of the tail-stalk (https://www.shutterstock.com/it/image-photo/herd-blesbok-on-grassy-plain-one-378605818).

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

In extreme individuals, the whole of the tail-tassel is pale (https://animalia-bio.us-east-1.linodeobjects.com/animals/photos/full/original/blesbok-damaliscus-pygargus-phillipsi.webp).

In the blesbok, the tail is raised at times (https://www.inaturalist.org/observations/116855609). As mentioned above, this includes adult males in the courtship display:
see from about 15 seconds in https://www.youtube.com/watch?v=VWM5FJCLLfs
https://www.istockphoto.com/photo/blesbuck-and-plain-zebras-in-mlilwane-wildlife-sanctuary-swaziland-gm1182437620-332029147?phrase=pics%20of%20a%20blesbok
https://www.inaturalist.org/observations/10063549

As in the bontebok, this arguably qualifies the colouration of the tail as a caudal flag, in a social/sexual context.

However, the tail of the blesbok seems undemonstrative in the context of anti-predator reactions.

Like the bontebok, the blesbok wags/swishes its tail only in reaction to insects (https://www.istockphoto.com/photo/african-blesbok-in-the-african-bush-veld-gm1091176214-292722242?phrase=pics%20of%20a%20blesbok), except for the social wagging described above.

The only relevant instance is when the blesbok stands in mild alarm at the approach of a potential predator, then simultaneously performs the three following actions:

  • snorting once,
  • vigorously swishing the tail once, and
  • moving the legs as walking is initiated.

DAMALISCUS LUNATUS/KORRIGUM/TOPI/JIMELA

Estes (1993, page 115) mentions the following displays of the tail, in Damaliscus lunatus/korrigum/topi/jimela:

"Territorial Advertising: High-stepping in erect posture, with ears lowered and tail out. Herding and courtship display"

https://www.youtube.com/watch?v=-8R2Lp_S9Es
https://www.flickr.com/photos/90785747@N02/25779599611
https://www.shutterstock.com/it/image-photo/topi-massai-mara-1266686257
https://www.shutterstock.com/it/image-photo/topi-massai-mara-1266686242
https://www.alamy.com/stock-photo-topi-running-masai-marakenya-57612950.html?imageid=D3BA60CD-B021-42FE-BD27-B0BF39ADEB89&p=50837&pn=1&searchId=1acbb4918a3fb248f068c8228e9df229&searchtype=0

"Courtship: Standing stiffly behind female in erect posture with tail raised. Prelude to mounting"

The following, of jimela, show stotting (other than proud-trotting) in lunatus/korrigum/topi/jimela (https://www.shutterstock.com/it/image-photo/on-sunny-day-find-some-topis-2172550751 and https://www.dreamstime.com/royalty-free-stock-photos-beautiful-topi-antelope-mara-grassland-antelopes-resembles-hartebeest-differs-dark-purple-patchings-their-upper-image38932518 and https://www.dreamstime.com/royalty-free-stock-photos-topi-antelope-running-grassland-masai-mara-antelopes-resembles-hartebeest-differs-dark-purple-patchings-their-upper-image39073078). They show that, during this antipredator display, the tail - far from being raised - is actually tucked in.

In the case of D. lunatus lunatus, according to Joubert (https://journals.co.za/doi/abs/10.10520/AJA00445096_270):

"Severe or high intensity fighting...During the pushing duel the two males - still on their knees - interlock their horns and with tails either drawn in between the legs or switching from side to side try to push one another off the mark...When displaying to the females...in the low intensity form of this display the...bull retains his normal walking gait while the tail hangs loosely down or is withdrawn between the hind legs. In the high intensity form the legs and tail also enter into the display...movements are slow and delicate while the front legs are lifted high...with each stride forward and placed down carefully and gently, the movements slow but deliberate. The tail is lifted in accordance with the intensity of the display and in extreme cases is lifted above the horizontal plane. By means of this display the bull asserts his dominance over the cows...The high intensity form of the display is almost invariably assumed when the bull returns to his cows after a dispute with a rival male. Also at waterholes - where there is occasionally contact between adjoining herds - the display is conspicuous...If a male approaches a youngster it displays the submissive posture...Submissiveness is signified when an immature lifts his head up high, pulling its chin in tightly...Simultaneously the tail is held rigidly and horizontally away from the body. If being chased by the bull the immature retains this posture while giving long, stiff-legged bounds (stotting action). If the chase is severe this pace is too slow and the calf reverts to the normal manner in which the animals run at high speed. This applies to both male and female calves".

DISCUSSION

The following mislabelled photo, of Alcelaphus caama, may help to put the genus Damaliscus into perspective, in terms of conspicuous colouration of the tail (https://www.markeisingbirding.com/index/tsessebe). Please also scroll to the accompanying photo that includes an infant individual, in which the tail is already conspicuously dark.

In no species/subspecies of Damaliscus is the tail as conspicuous in colouration, or as obviously activated while fleeing, as in A. caama.

In Damaliscus, a caudal flag is plausible in a social/sexual context, activated mainly in mature males. The tail-tassel is large and dark enough, and contrasts enough with pale pelage on the buttocks and rump, for there to be a considerable display, particularly in courtship and masculine territoriality.

This applies even to

However, a caudal flag in Damaliscus seems unlikely in an anti-predator context. This is because there seems to be no significant display of the tail in stationary alarm or fleeing.

However, observations are needed of juveniles stotting in reaction to the arrival of predators - which has not been described in the literature, let alone photographed. If the activation of the tail described for the tsessebe by Joubert applies not only intraspecifically (in appeasement of masculine aggression) but also interspecifically (in display of individual fitness to cursorial carnivores), then this possibly occurs also in the bontebok, the blesbok, the topi, and the korrigum.

I repeat the following (https://www.youtube.com/watch?v=gnRO9HlPgo4), in the interests of giving Readers an engaging search-image.

For an index to my many Posts about the genus Damaliscus, please see https://www.inaturalist.org/journal/milewski/78238-an-index-to-my-posts-on-genus-damaliscus#.

Publicado el mayo 11, 2023 12:26 MAÑANA por milewski milewski

Comentarios

At birth, no dark is apparent on the tail, in any species/subspecies of Damaliscus.

Damaliscus jimela:

https://www.shutterstock.com/it/image-photo/baby-topi-masai-mara-kenya-1244536396

However, blackish starts to appear within weeks of birth.

Damaliscus jimela:

https://www.shutterstock.com/it/image-photo/baby-topi-antelope-standing-grass-serengeti-1296795187

Publicado por milewski hace 12 meses

The following happens to reveal the true length of the fleshy/skeletal part of the tail of Damaliscus jimela:

https://www.inaturalist.org/observations/102370579

This shows that the length of fleshy/skeletal tail equals the distance from the tip of the muzzle to the posterior edge of the orbit, in adult females.

Publicado por milewski hace 11 meses
Publicado por milewski hace 11 meses

Agregar un comentario

Acceder o Crear una cuenta para agregar comentarios.