Extreme fang-baring displays: examples in African carnivores
Mammalian carnivores include felids, canids, hyenids, mustelids, herpestids, viverrids and others (https://en.wikipedia.org/wiki/Carnivora). All have canine teeth as an important part of their weaponry. All are likely to defend themselves by biting, and all might be expected to show their canines as a deterrent to would-be attackers.
However, fang-baring displays are surprisingly variable among carnivores, even within a given family.
Most families of carnivores lack fang-baring displays beyond just the opening of the mouth. It is only in felids, some canids and a few mustelids that displays of the upper canines are well-developed. Even within the felids and canids, there is surprising variation in the facial expressions both anatomically and in terms of patterns of colouration which accentuate the displays.
This variation can be illustrated, within the African fauna, by means of just four species: the leopard (Panthera pardus), the caracal (Caracal caracal), the African golden wolf (Canis anthus) and the black-backed jackal (Lupulella mesomelas).
Several genera of felids have fang-baring displays, but what varies greatly is the associated colouration. The face of the leopard has completely inconspicuous colouration, which means that the fang-baring expression is purely a matter of exposing the pale canines and dark lips (https://photos.com/featured/close-up-of-leopard-growling-wim-van-den-heever.html?product=art-print and https://dissolve.com/stock-photo/Leopard-growling-Greater-Kruger-National-Park-South-royalty-free-image/101-D1028-85-811). By contrast, in the caracal there is a 'warpaint' effect owing to dark/pale contrasts on the fur, which change shape as the face is contorted (https://www.agefotostock.com/age/en/details-photo/caracal-caracal-caracal-felis-caracal-spitting-namibia/BWI-BS356922/1 and https://www.agefotostock.com/age/en/details-photo/caracal-felis-caracal-spitting-snarling/BWI-BLW029571/1). This 'ominous makeup' is restricted to only a few species of carnivores, all of them felids. And by the same token some felids, such as the Canada lynx (Lynx canadensis), hardly fang-bare at all, let alone possess associated colouration.
Canids vary surprisingly in the incidence of fang-baring displays, and it is in the genus Canis that they are extremely developed. In the African golden wolf the face is contorted even more than in felids (https://en.wikipedia.org/wiki/African_golden_wolf#/media/File:Canis_anthus_threat_postures.png and https://external-preview.redd.it/MyxvFu3vsXJzYXbspo-m6GkfcfUMUSnNc6Hlyasjtnw.jpg?auto=webp&s=faaaab5cc13276a4c07bd8f742bbb68554847603 and https://stock.adobe.com/images/a-golden-jackal-animal-in-anger-and-fight-mode-in-nature/246623708). By contrast, the face of the black-backed jackal remains uncontorted regardless of the intensity of emotion (https://www.flickr.com/photos/mvukovich_digiscope/40485635433/ and http://lh4.ggpht.com/-nCRTnIZrjzk/TwRubSUqKpI/AAAAAAAAOMY/kVHcbbU0ZiQ/s1600/vulture-jackal_1858443i%25255B4%25255D.jpg and https://www.gettyimages.co.uk/detail/photo/two-black-back-jackals-fighting-by-a-waterhole-royalty-free-image/1204595106?adppopup=true and https://www.naturepl.com/stock-photo-black-backed-jackals-fighting-canis-mesomelas-savute-chobe-national-nature-image01117639.html and https://www.naturepl.com/stock-photo-canis-mesomelas-nature-image00761070.html and https://www.dreamstime.com/two-black-backed-jackals-fighting-snarling-each-other-jackals-fighting-teeth-showing-image106825166 and https://www.kimballstock.com/popuppreview.asp?db=a&image=AFW+26+MH0003+01&itemw=4&itemf=0001&itemstep=1&itemx=16).
So here is food for thought. The caracal and the black-backed jackal coexist widely, have similar body sizes, and are persecuted by the same guild of larger carnivores. Why would their modes of self-defence differ so much in the displaying of the upper canines?
Comentários
Although there are few photos of the fang-baring display of Canis anthus, the more familiar Eurasian jackal (Canis aureus) is similar: https://www.dreamstime.com/stock-photo-golden-jackal-canis-aureus-adult-threathening-image56847976 and https://www.flickr.com/photos/tick-my_pictures/27332240511 and https://www.alamy.com/golden-jackal-canis-aureus-stands-threatening-in-a-meadow-romania-biosphaerenreservat-donaudelta-image255389507.html and https://www.sciencephoto.com/media/1091236/view/golden-jackal-snarling and https://www.naturepl.com/stock-photo-nature-image01604364.html and https://www.alamy.com/stock-image-golden-jackal-canis-aureus-snarling-in-aggressive-posture-danube-delta-165855547.html and https://www.123rf.com/photo_42905540_euroepan-golden-jackal-canis-aureus-is-threatening.html and https://www.natureinstock.com/search/preview/golden-jackal-canis-aureus-snarling-danube-delta-romania/0_00118524.html.
Because Jackals scavenge from other carnivores and any display to another bigger carnivore will be known as bluff. By contrast, Caracal will be a novelty to most carnivores - at least close up - and "bluff" may work.
Are Chacmas worth a little mention here: They really expose their canines to good effect. Do many other primates do this (to carnivores)?
@tonyrebelo Good thinking. The concept of bluff is important. For example, when the leopard fang-bares, I think most of us would agree that there is not much bluff involved because there is no exaggeration of the prospective harm, merely a warning. But what about the caracal? I do see a case for bluff in the sense that if I tangled with the caracal it would be not the fangs but the claws I would be concerned about (and more specifically damage to my eyes). So the caracal is exaggerating in the sense of pointing to its canines, not so? Look at the warpaint on the face of Puma concolor as it fang-bares. Is this bluff/exaggeration, and if not why do all puma-size felids not have similar warpaint?
@tonyrebelo I think your idea is a good one that most large predators will be unfamiliar with the caracal, and will therefore hesitate. I don't think bluff is an apt description of this but the persuasion being deployed by the caracal is, I agree, not just a matter of honest warning. Could we explain the unusual warpaint of the caracal as the adaptive result of a combination of a) extreme risk with so many large carnivores around, and b) habits so secretive that the caracal is encountered too seldom to become familiar with?
@tonyrebelo Fang-baring in the primates is a whole topic in itself, and overdue for scrutiny. I don't know offhand of any primate which fang-bares in the same way as felids or Canis. The fang-baring of male baboons is indirect and mainly intraspecific/social, and I doubt that male baboons fang-bare to carnivores when cornered. Much to think about here...
By the way, it is interesting that both the black-backed jackal and the caracal have encephalisation quotients of 1.3, making them considerably brainier than lion, leopard or cheetah (see https://www.tandfonline.com/doi/pdf/10.1080/02541858.1984.11447899). The jackal manifests its braininess in monogamous pairwork and outmanoeuvering antagonists, whereas the caracal manifests its braininess in avoiding contact and then persuading?
A remarkable video ('Jackals VS Caracal, Kgalagadi') contained within the following website shows a single individual of the caracal succeeding in stealing prey from a pair of the black-backed jackal: https://owlcation.com/stem/Caracal-Adaptations-and-Facts.
Adicionar um Comentário