02 de agosto de 2021

Three odd gaits in one brief video

Today I stumbled upon a video clip so packed with biological interest that I would recommend watching it before it vanishes from the Web: https://www.getaway.co.za/environment/aardvark-outwits-brown-hyena/, the location being https://en.wikipedia.org/wiki/Mabula_Game_Reserve.

We see an individual of the aardvark (Orycteropus afer, https://en.wikipedia.org/wiki/Aardvark) foraging in broad daylight, which is already exceptional because this is one of the most strictly nocturnal of large African mammals.

Then enters an individual of the brown hyena (Parahyaena brunnea, https://en.wikipedia.org/wiki/Brown_hyena), an ostensible specialist on scavenging and an exceptional sighting in its own right although this species is not strictly nocturnal.

Bear in mind that the protagonists are about like-size (brown hyena adult averages 40 kg), but with divergent morphological specialisations. The aardvark is the largest specialised eater of termites and ants on Earth, with extremely muscular legs and large claws. The brown hyena has bone-crushing teeth (see https://en.wikipedia.org/wiki/Brown_hyena#/media/File:Hyaena_brunnea_1zz.jpg) and extremely economical hindquarters in which the shortness of the hind feet is compensated by extreme swing of the tarsal joint. The aardvark is designed to dig extremely rapidly whereas the brown hyena is designed to walk long distances on an empty belly.

Action: the brown hyena chases the aardvark at full sprint, apparently intent on killing it in defiance of any reputation as a mere scavenger. Can the bite of this 'postcarnivore', unaccompanied by any sharp claws, possibly subdue such nuggety prey?

The brown hyena catches up, but the aardvark manages to somersault down a hole, frustrating the would-be killer. Then, a group of the blue wildebeest (Connochaetes taurinus taurinus), an odd-looking species in its own way, chases the brown hyena off the scene, in a surprising show of aggression towards this 'mere scavenger'.

What interested me particularly is that this footage revealed one new gait every minute. These species can all gallop, but they are strangely divergent in the sequence of limb-movements when not sprinting - perhaps because they are so peculiar morphologically that they look like chimeras.

The aardvark seems like a badger-on-ballet-shoes with a conical tail, a tubular snout and hare-like ears. The brown hyena has a strangely sloping back and long neck, nosferatu-ears, and a cross-grained cape-like mane. And the blue wildebeest also has a sloping back and a strange mane and tail. And each is odd in its locomotory gearing, although not necessarily rhyming with reason.

The aardvark is perhaps the only fully terrestrial, digitigrade, mammal which uses a perfect cross-walk, the legs moving in diagonal pairs (see https://www.kimballstock.com/results.asp?db=a&txtkeys1=aardvark and https://creatures-of-the-world.fandom.com/wiki/Aardvark?file=Aardvark_fs.jpg). This has not been pointed out in the literature but is obvious once one develops a search-image for walking gaits.

The brown hyena has its own odd walk in that the 'hock' seems hypermobile (see https://upload.wikimedia.org/wikipedia/commons/b/be/Brown_Hyena_%28Parahyaena_brunnea%29_%286472940707%29.jpg). But what is really unusual is that, instead of trotting like other carnivores, it paces like a camel. (Watch for this after the aardvark vanishes and the brown hyena gives up on digging.) Also see https://www.earthtouchnews.com/natural-world/predator-vs-prey/guess-what-this-brown-hyena-had-for-dinner/.

And, for its part, the blue wildebeest is also more reluctant to trot than most other ungulates, gearing up from a walk straight into a canter (see https://videohive.net/item/wildebeests-walking-and-running/26412070 for a different species of wildebeest).

So here we have an expose of specialised gaits which have yet to be explained in adaptive terms. The aardvark has slowed down the trot to convert the same limb-movements into a walk. The brown hyena has speeded up its walk in replacement of any trotting gear. And the blue wildebeest has just skipped the trot, going from first gear straight to third.

'Go figure'.

Ingresado el 02 de agosto de 2021 por milewski milewski | 0 comentarios | Deja un comentario

Eye-white displays and what we should call them, part2

In the human species, eye-language works partly because the sclera is paler than the iris, the eyelids, and the eyebrows. 'Adaptive colouration' is involved, because without some degree of pale/dark contrast the subtle shiftiness of the eyeballs would hardly be visible even at conversational distances. Human scleral displays are therefore in principle similar to the many other small-scale social (intraspecific) displays found in various other mammals; and a scientific term should be aligned accordingly.

In a previous Post, I coined the term 'semet' for any feature of adaptive colouration which is too small-scale to be conspicuous to scanning predators, but conspicuous enough at close quarters to aid social communication. According to this approach, could we say that the human species possesses a 'scleral semet'?

To see how hidden the eyes of apes are by pigmentation of the sclera, compare https://www.alamy.com/stock-photo-orangutan-pongo-pygmaeus-close-up-of-the-face-49328105.html with the albino version https://www.independent.co.uk/news/world/asia/albino-orangutan-rare-borneo-blonde-hair-blue-eyes-central-kalimantan-region-indonesia-borneo-survival-foundation-a7715836.html; and compare https://www.istockphoto.com/photo/close-up-of-a-male-western-gorilla-gm892726338-247038308 with https://i.redd.it/3p9hflrl0h261.jpg.

Although the apes generally lack any scleral semet, several species of monkeys resemble humans in this way: https://www.sciencephoto.com/media/1091429/view/tibetan-macaque-eyes and https://www.gettyimages.com.au/detail/photo/southern-or-sunda-pig-tailed-macaque-mature-male-royalty-free-image/591073170?adppopup=true and https://www.gettyimages.com.au/detail/photo/portrait-of-a-lion-tailed-macaque-macaca-silenus-royalty-free-image/1016151852 and https://paychecksforlife.blogspot.com/2020/11/monkey-with-blonde-hair.html and https://mycbs4.com/news/local/gallery/jungle-friends-primate-sanctuary-searching-for-escaped-capuchin-monkey-near-gainesville?photo=1#photo-2 and https://www.monkeysanctuary.co.za/capuchin-monkey and

Interpretation of scleral semets in monkeys is complicated not only because the phylogenetic sprinkling of these species seems so random but also because monkeys have other semets in which it is the eyelids that are conspicuously pale (https://www.agefotostock.com/age/en/details-photo/northern-pig-tailed-macaque-macaca-leonina-portrait-with-eyes-closed-thailand-khao-yai-national-park/BWI-BS373272). There thus arises a distinction between scleral semets and other types of ocular semets.

Certain species of baboons (Papio) exemplify this because they have pigmented, inconspicuous scleras but pale upper eyelids that are displayed by exaggerated blinking. Compare https://fineartamerica.com/featured/close-up-of-an-olive-baboon-papio-animal-images.html with https://www.freepik.com/free-photo/closeup-shot-baboon-monkey-with-blurred-background_12305937.htm and the more revealingly illuminated https://www.shutterstock.com/nb/image-photo/close-shot-baboon-sitting-grass-1988070962.

Ingresado el 02 de agosto de 2021 por milewski milewski | 0 comentarios | Deja un comentario

Eye-white displays (starting with humans) and what we should call them, part 1

Everyone knows that in the human species the movements of the eyes can be expressive enough to outweigh the words spoken, e.g. when lies are being told. And that the sclera, i.e. the white of the eye, accentuates the tiny movements of the eyeballs, as if to spell out the unspoken messages in a rapid series of triangular flickers.

And many may have noticed that the selective breeding of the domestic dog has inadvertently made canine eyes more human-like in their expressions of emotion, partly by exposing the sclera (https://abc13.com/dog-study-can-dogs-communicate-with-humans-eyes-intelligence/5351460/ and https://www.jsonline.com/story/news/2019/08/19/puppy-dog-eyes-dogs-evolved-eyebrow-muscle-help-bond-humans/1867592001/).

What is less-known is that our closest relatives among the primates are not only unlike us in this way, they are in some sense the antithesis. They have a sclera so pigmented that it seems adapted actually to hide intentions and emotions, keeping the eyes inscrutable.

And that the eyes of hyenas are more expressive in the human sense than those of most other animals.

And that those large mammals which we humans tend to regard as rather expressionless may have analogous systems operating about their ears, which are far more mobile than human ears and more relevant to the sensory priorities of the species involved.

In this initial Post I illustrate some of these points, helping to put our human eye-white displays into a broader biological context. In later Posts I will propose the term 'scleral semets' for the features of adaptive colouration involved in communication by means of 'eye language'. And, as if by digression, I will return to the subjects of my most recent Posts, namely the felids, to listen to their ear-language with new eyes.

The following show how pigmented the sclera is in chimpanzees and gorillas, as if to achieve the opposite of the facilitation seen in humans: https://www.smithsonianmag.com/science-nature/bonobos-teach-humans-about-nature-language-180975191/ and https://www.naturalworldsafaris.com/holidays/africa/congo/the-ultimate-gorilla-safari.

The following show the difference between the wolf, in which the sclera is tightly covered by the eyelids, and the domestic dog, in which the sclera is exposed: https://www.canstockphoto.com/wolf-eyes-7820377.html and https://depositphotos.com/85058888/stock-photo-close-up-on-dogs-eyes.html and https://www.theatlantic.com/science/archive/2019/06/domestication-gave-dogs-two-new-eye-muscles/591868/.

The following show how much more of the sclera is visible in hyenas than in the wolf or most wild canids: https://www.flickr.com/photos/tambako/12796302043 and https://www.istockphoto.com/video/brown-hyena-being-harassed-by-jackal-gm1138822949-304180773.

The following show that the cheetah, unusually for felids, displays the sclera in fear: https://www.photosincolor.com/wildlife-photographer-captures-amazing-photos-of-deadly-cheetah/.

Ingresado el 02 de agosto de 2021 por milewski milewski | 0 comentarios | Deja un comentario

31 de julio de 2021

Forearm flags and caudal flags in lynx-like felids

Lynx-like felids comprise four species of Lynx, the serval (Leptailurus serval, see https://www.youtube.com/watch?v=iBUJrdKG9jc and https://www.youtube.com/watch?v=aKeBUIvfnAw), the African golden cat (Caracal aurata, see https://www.davidmillswildlife.com/african-golden-cats and http://www.catsg.org/index.php?id=106 and https://news.mongabay.com/2015/08/feline-unseen-the-african-golden-cat/) and the caracal (Caracal caracal, https://www.biolib.cz/en/image/id175286/ and https://www.youtube.com/watch?v=WEQjsh934vc).

All are medium-size (about 10 kg) for felids, with relatively short tails (e.g. see https://www.clawantlerhide.com/tails/Bobcat%20Tails and https://www.clawantlerhide.com/tails/Bobcat%20Tails). The African golden cat, caracal, bobcat (Lynx rufus) and Eurasian lynx (Lynx lynx) are dietary generalists, whereas the serval, Iberian lynx (Lynx pardinus) and Canada lynx (Lynx canadensis) specialise on rodents or lagomorphs.

Lynx-like felids are surprisingly inconsistent in two aspects of conspicuous colouration, namely forearm flags and caudal flags.

The forearm flag is a conspicuously dark-and-pale feature on the inner surface of the foreleg, the ostensible function of which is to remind would-be attackers of the hazard of the claws. This is analogous with the way the fang-baring expression of the caracal is accentuated by bold facial colouration (see my Post of July 24, 2021).

The forearm flag is incongruous with the camouflage colouration of the legs and torso, but is normally hidden by its low, inner position on the figure. It is activated in defensive postures, by bracing or slapping the foreleg forward to reveal the bold pattern - as seen in action here: https://www.youtube.com/watch?v=KMFO2n6H6XU and https://www.earthtouchnews.com/natural-world/animal-behaviour/cat-fight-serval-holds-its-own-in-a-showdown-with-a-cheetah/ and https://www.youtube.com/watch?v=96_Fbhg9oBE.

The caudal flag is a conspicuously dark-and-pale feature on the tail, activated by the lifting of the tail while walking or standing. The adaptive value of this signal is unknown.

Only the bobcat and the serval possess forearm flags. All of the species of Lynx possess caudal flags; by contrast the remaining species have undemonstrative tails. And, to make the picture even less consistent, the caudal flag is questionable in the Canada lynx because its tail is so short that it hardly remains conspicuous.

Bobcat forearm flag: https://upload.wikimedia.org/wikipedia/commons/3/30/Bobcat_photo.jpg and https://www.inaturalist.org/observations/30230527 and https://www.inaturalist.org/observations/52408718 and https://en.wikipedia.org/wiki/Bobcat#/media/File:Calero_Creek_Trail_Bobcat.jpg and https://en.wikipedia.org/wiki/Bobcat#/media/File:Bobbie_2010_2.jpg

Serval forearm flag: https://i.redd.it/eqy0dvtzt1231.jpg and https://live.staticflickr.com/7146/6442193527_bf0b603898_b.jpg and https://www.flickr.com/photos/nostri-imago/3425081077 and https://www.africansafaris.co.nz/blog/the-super-sleek-serval/ and https://www.inaturalist.org/observations/40300206

The African golden cat is unusually variable in colouration, but even its most graphic pattern on the inner foreleg fails to qualify as a forearm flag: https://www.flickr.com/photos/pantheracats/6046710834.

Bobcat caudal flag: https://www.mendonomasightings.com/2014/05/21/a-confident-bobcat-as-photographed-by-thom-matson/ and https://www.facebook.com/newscentermaine/photos/a.97048189612/10155342593774613/ and https://www.mercurynews.com/2016/11/29/was-that-a-bobcat-in-antioch/

Iberian lynx caudal flag: https://www.theguardian.com/environment/2020/oct/25/the-lynx-effect-iberian-cat-claws-its-way-back-from-brink-of-extinction and https://theeuropeannaturetrust.com/animal-profile-iberian-lynx/ and https://www.earth.com/news/iberian-lynx-resurrection/ and https://www.photo-logistics.com/listings/hide-of-iberian-lynx-in-andujar/ and https://www.wisebirding.co.uk/southern-spain-iberian-lynx-eagles-cranes/

Eurasian lynx caudal flag: https://www.facebook.com/lynxuktrust/photos/a.451014284948269/870742009642159/ and https://www.coniferousforest.com/wp-content/uploads/2015/10/Eurasian-Lynx-Pictures.jpg and https://www.123rf.com/photo_105736894_eurasian-lynx-showing-teeths-in-forest-at-summer.html and https://www.agefotostock.com/age/en/details-photo/eurasian-lynx-lynx-lynx-male-in-summer-germany-saxony/BWI-BS348257

Canada lynx, which only marginally qualifies for a caudal flag: https://www.naturepl.com/stock-photo-canada-lynx-nature-image00641562.html and https://www.facebook.com/101977034910391/photos/a.101979591576802/101978654910229 and https://www.agefotostock.com/age/en/details-photo/canada-lynx-lynx-canadensis-canada-alaska-n-usa/AAM-AAES67410 and https://stock.adobe.com/search?k=%22canada+lynx%22&asset_id=386546544 and https://www.joelsartore.com/wp-content/uploads/stock/ANI019/ANI019-00313.jpg and https://www.canadiangeographic.ca/article/animal-facts-canada-lynx and https://twitter.com/bigcatswildlife/status/1134046151563341824 and https://www.nature.ca/notebooks/english/lynx_p4.htm

The following is unusual in showing the tail of the caracal raised. However, it is being swung rather than held upright: https://www.goodfon.com/download/rys-karakal-priroda-poza-progulka-boke-fon-poliana-trava-sve/2000x1333/. Ditto for the serval: https://www.inaturalist.org/observations/76653774. However, I am puzzled by the following photo: https://www.inaturalist.org/observations/67697166.

Ingresado el 31 de julio de 2021 por milewski milewski | 2 comentarios | Deja un comentario

Protective mimicry in the cheetah, part 4

Everyone knows that, among all the felids, the cheetah has the oddest colouration in infants; and that the best explanation so far is protective mimicry of the honey badger (Mellivora capensis, see https://cheetah.org/canada/2019/04/02/the-key-to-cheetah-cubs-survival/).

However, what has been widely overlooked is how caricaturised and chimaeric this resemblance is, and the implications for other, more subtle, features of colouration in the cheetah.

The colouration of infants of the cheetah (see https://www.shutterstock.com/nb/image-photo/cheetah-cub-clearing-park-fall-1690349212 and https://www.shutterstock.com/nb/image-photo/small-fluffy-cheetah-cub-standing-on-86857843 and https://fineartamerica.com/featured/2-serious-tiny-cheetah-cubs-caroline-ellis.html and https://www.wildsoulconservation.com/product/cheetah-cub-stalking-practice/ and https://www.unilad.co.uk/animals/adorable-cheetah-cubs-say-hello-to-the-world-as-they-take-their-first-steps/) resembles that of the honey badger in only one way: that the usual relationship between shading and countershading is inverted. Instead of the underparts being relatively pale to compensate for shading, it is the back that is pale. If such a crude resemblance works to intimidate would-be attackers, this is because a) this inversion is so powerfully aposematic that it outweighs any incongruities, and b) it is viewed at sufficient distance that only the overall impression counts.

The most obvious incongruity is seen in the head of infants of the cheetah, which remains so unlike the honey badger that the figure looks like a chimaera rather than a plausible example of integrated adaptive colouration.

To summarise this four-part series of Posts: the case for protective mimicry in the cheetah rests on the models being the honey badger for infants, and females of the lion for adults. The resemblance, although imprecise, works well enough to outweigh the obviously kitten-like face of infants and the obviously slender figure of adults. This effectiveness rests on artful caricature at distance of the following features in particular: in the case of infants, inverse countershading; and in the case of adults a) dark back-of-ear offset by pale side of neck, b) dark-and-pale tail-tip, c) whitish mouth, d) pale chest in sitting posture, and e) differentiation of the muzzle from the rest of the face.

With the above rationale in mind, do readers still see the following figures as categorically different and beyond confusion of identity, regardless of illumination or distance: https://fineartamerica.com/featured/sub-adult-cheetah-landscape-etienne-outram.html and https://www.dreamstime.com/royalty-free-stock-photos-kalahari-lion-kgalagadi-image15304738?

Ingresado el 31 de julio de 2021 por milewski milewski | 0 comentarios | Deja un comentario

30 de julio de 2021

Protective mimicry in the cheetah, part 3

A subtle aspect of the colouration of females of the lion is that both the mouth and the chest are so pale as to be conspicuous in certain lights. The cheetah shows a similar pattern, differing from the leopard and most other large felids in this way. The spotless whiteness of the chin and throat of the cheetah are anomalous relative to the camouflage-pattern on most of its fur. As a result the cheetah, like females of the lion, can at distance look gleamingly pale on the front when sitting. See https://www.gettyimages.com.au/detail/photo/portrait-of-lion-sitting-on-rock-royalty-free-image/1271814971?adppopup=true and https://www.wallpaperbetter.com/en/hd-wallpaper-apzoz and https://wildlifereferencephotos.com/media.details.php?mediaID=38923 and https://www.australiazoo.com.au/wildlife/our-animals/cheetahs/ and https://www.publicdomainpictures.net/en/view-image.php?image=41746&picture=cheetah-in-profile.

The cheetah possesses the strongest example of a malar stipe in all the felids, and this feature is absent in the lion. The malar stripe may, at distance, give a deceptive impression of depth to the relatively small, flattish face of the cheetah. See https://avatarfiles.alphacoders.com/222/222732.jpg.

The following photos show the similarly pale frontal aspects of the two species. Compare females of the lion (https://focusedcollection.com/164924450/stock-photo-lioness-sitting-on-grass.html and https://www.alamy.com/lion-panthera-leo-lioness-sitting-on-grass-looking-toward-camera-kenya-masai-mara-national-park-image360919468.html and https://www.bigstockphoto.com/image-30586892/stock-photo-lioness-sitting-in-open-grassland and https://www.shutterstock.com/nb/image-photo/lioness-sitting-on-hill-1210103518) with the cheetah (https://depositphotos.com/221777980/stock-photo-cheetah-sits-long-grass-profile.html and https://www.alamy.com/cheetah-acinonyx-jubatus-image7758377.html and https://www.shutterstock.com/nb/image-photo/cheetah-seen-on-safari-while-hunting-1831407343).

Females of the lion have a pale panel on the side of the neck, which is a result of sheen as much as depigmentation. When viewed partly from behind, this provides dark/pale contrast with the back-of-ear. It may be more than coincidence that the spotting of the cheetah tends to lapse on the corresponding surface of the neck. I suspect that the pale effect in the lion is partly a matter of reflection of ultraviolet (which felids can see) and that the cheetah shares the reflective pattern more in terms of ultraviolet than in terms of depigmentation. See https://www.robertharding.com/preview/1174-5224/side-profile-lioness-sitting-panthera-leo-ears-up/ and https://www.goodfon.com/download/gepard-morda-profil-ohota/1920x1275/ and https://www.shutterstock.com/nb/image-photo/cheetah-photography-masai-mara-1008002893 and https://www.masterfile.com/image/en/700-02887427/cheetah-masai-mara-kenya.

To be continued...

Ingresado el 30 de julio de 2021 por milewski milewski | 0 comentarios | Deja un comentario

Protective mimicry in the cheetah, part 2

In summarising so far, consider the following photo: https://www.alamy.com/stock-photo-one-cheetah-adult-female-walking-through-open-grassland-against-the-129036465.html. The dark punctuation on the back-of-ear, and the dark-and-pale punctuation on the tail-tip, are similar enough to those of females of the lion (https://www.flickr.com/photos/davidbygott/6039165459) that, in a distant view, confusion of identity can arise. And there is also potential confusion with the leopard, which shares these patterns.

It is unlikely to be mere coincidence that cheetah, lion and leopard, which widely coexisted in Africa and Eurasia, have similar patterns on the back-of-ear. Most species of felid have different patterns, in which there is a central pale spot. The range of variation is represented in the following selection: Panthera tigris https://www.istockphoto.com/photo/tiger-ears-gm89923374-2355780, Panthera onca https://upload.wikimedia.org/wikipedia/commons/7/74/Jaguar_%28Panthera_onca%29_male_back_in_the_water_%2829173428825%29.jpg and https://notquitecountrygirl.typepad.com/.a/6a01901e6a543d970b0240a4c53974200d-pi and https://www.naturepl.com/stock-photo-jaguar-panthera-onca-head-portrait-rear-view-showing-ear-spots-captive-image01319094.html, Panthera uncia https://www.flickr.com/photos/thisisnodream/35461803610, Puma concolor https://www.pond5.com/stock-footage/item/82177040-puma-lay-thick-bush-turning-head-looking-and-lay-down-behind and https://twitter.com/catameep/status/1143973676293005312/photo/2, Lynx rufus https://www.facebook.com/bigcatrescue/photos/a.184533141956/10155970456221957/ and https://forfoxsakewildlife.com/2019/11/03/bobcats-have-eye-spots-on-their-ears/, Lynx lynx https://www.alamy.com/eurasian-lynx-lynx-lynx-head-with-tufted-ears-from-behind-captive-image280645324.html, Leptailurus serval https://www.shutterstock.com/image-photo/ears-serval-cat-694062445?src=IS1FgdKNZBGHaYht68sMfw-1-3 and https://www.alamy.com/stock-photo-serval-cats-unique-striping-on-ears-32081728.html, Leopardus pardalis https://www.alamy.com/stock-photo-ocelot-leopardalis-pardalis-showing-distinctive-black-and-white-markings-29428865.html, Leopardus wiedii https://www.mindenpictures.com/stock-photo-margay-leopardus-wiedii-showing-white-ear-spots-on-the-back-of-the-naturephotography-image00539134.html, and Neofelis nebulosa https://www.imago-images.com/st/0091704447.

In the lion, this pattern has been modified by shifting the pale spot to the upper margin. This shift seems to have been mimicked by both the cheetah and the leopard, in such a way that the cheetah can benefit from resemblance to both lion and leopard. However, the cheetah is generally seen at distance in vegetation too open for the leopard, which means that the crucial resemblance is that to the lion.

In the case of the tail-tip, the resemblance of the patterns is only approximate when viewed close-up and stationary. Furthermore, the leopard (https://www.alamy.com/stock-photo-view-of-leopards-tail-panthera-pardus-elephant-plains-sabi-sands-conservancy-22796253.html) does not mimic the lion in the appearance of its tail (see my Posts of July 23 & 27, 2021). However, mimicry remains possible at distance because the frequent movement of the tail means that all that is needed is an impression of a combination of dark and pale close together (https://www.dreamstime.com/male-lion-walking-tall-grass-tail-held-high-male-lion-walking-tall-grass-tail-high-air-green-image133475307 and https://www.deviantart.com/8twilightangel8/art/African-Cheetah-Profile-389025185 and https://stock.adobe.com/ca/images/cheetah-front-view-full-body/218059124).

To be continued...

Ingresado el 30 de julio de 2021 por milewski milewski | 2 comentarios | Deja un comentario

Protective mimicry in the cheetah, part 1

Several times, while working in the Serengeti, I have felt sheepish after mistaking the cheetah (Acinonyx jubatus) for the lion (Panthera leo) at a distance. Is it possible that scale-dependent protective mimicry is at work here?

The colouration of the cheetah doubles as camouflage and a kind of caricature of females of the lion (e.g. see http://www.shahrogersphotography.com/detail/3831.html and https://depositphotos.com/378326094/stock-photo-young-cheetah-hunting-thomson-gazelle.html). How this is achieved is interesting both biologically and artistically.

The spots of the cheetah are so small that, at distance, they become plain fawn. At the same time, the punctuations on the back-of-ear and tail-tip are oddly convergent with those on females of the lion:

The following show relevant views of the cheetah. Please imagine the same figures farther away in order to envisage how the features might simulate those of females of the lion: https://www.jungledragon.com/image/14135/cheetahs_in_the_serengeti.html/zoom and https://www.alamy.com/cheetah-acinonyx-jubatus-prowls-in-the-grass-on-the-masai-mara-kenya-image5222217.html and https://www.alamy.com/cheetah-acinonyx-jubatus-three-cheetahs-in-the-savannah-kenya-masai-mara-national-park-image283409116.html and https://thenextcrossing.com/masai-mara-cheetahs.

The dark marking on the back-of-ear cannot be explained as part of the camouflage colouration of the cheetah: https://www.alamy.com/close-up-view-from-behind-of-cheetah-sitting-in-long-grass-maasai-image60169338.html and https://www.agefotostock.com/age/en/details-photo/cheetah-acinonyx-jubatus-showing-black-markings-on-back-of-ears/FHR-10252-00236-075 and https://www.alamy.com/stock-photo-an-adult-female-cheetah-and-cub-looking-away-from-the-camera-13869506.html.

Instead, it is remarkably similar to those of both the lion and the leopard (Panthera pardus).

For the lion see: https://www.istockphoto.com/photo/lioness-from-behind-gm176050939-10226879 and https://www.dreamstime.com/lioness-lying-down-savannah-close-up-lioness-panthera-leo-lying-down-savannah-seen-behind-masai-mara-kenya-image116536524 and https://www.dreamstime.com/stock-photo-missing-you-image1450410.

For the leopard see: https://dalbecphoto.files.wordpress.com/2010/02/leopard-1-of-1-3.jpg and https://www.istockphoto.com/photo/leopard-back-gm506154003-44858206 and https://www.alamy.com/stock-photo-african-leopard-panthera-pardus-pardus-adult-back-view-standing-in-55855313.html and https://www.istockphoto.com/photo/starring-leopard-from-behind-gm635928796-112507411 and https://www.istockphoto.com/photo/starring-leopard-from-behind-gm635928348-112506889 and https://www.istockphoto.com/photo/stalking-leopard-from-behind-in-kruger-gm694489004-128336215 and https://www.flickr.com/photos/1328/4289292880.

If the following figures were far enough away, one might possibly be confused about their identity: https://www.alamy.com/stock-photo-a-cheetah-sitting-amidst-grass-and-facing-the-other-direction-with-121181097.html and https://www.alamy.com/cheetah-acinonyx-jubatus-prowls-in-the-grass-on-the-masai-mara-kenya-image5222220.html. This is partly because the tail-tip is impressionistically similar to that of females of the lion despite being unmistakably different when seen close-up.

The following show the tail-tip of the cheetah: https://www.colourbox.com/image/cheetah-on-savannah-in-africa-image-20163151 and https://www.earth.com/news/cheetah-quickly-vanishing-planet/ and http://tenrandomfacts.com/wp-content/uploads/2014/04/Cheetah.jpg and https://www.alamy.com/adult-cheetah-standing-in-open-grassland-after-making-a-kill-acinonyx-jubatus-serengeti-national-park-tanzania-image281540334.html. The important point is the combination of blackish and whitish rather than their precise arrangement.

Little-known facts about the lion are that the tail-tassel is larger in females than in males, and in females and juveniles (but not mature males) there is a pale surface just proximal to the tassel, on the underside of the shaft (see https://www.dreamstime.com/african-lion-panthera-leo-cub-playing-mother-s-tail-masai-mara-park-kenya-image198635099 and https://www.dreamstime.com/lioness-tail-close-up-beautiful-cat-image208692840 and https://www.shutterstock.com/nb/video/clip-545329-lioness-tail-air-walks-off-lay-down). The pale is only conspicuous at certain angles, because it results from sheen as much as depigmentation: https://www.shutterstock.com/nb/image-photo/lioness-sitting-on-dry-grass-relaxing-1269528727 and https://www.alamy.com/two-african-lioness-tail-up-in-green-bush-in-kruger-national-park-south-africa-specie-panthera-leo-family-of-felidae-image269554290.html and https://www.dreamstime.com/royalty-free-stock-images-lioness-relaxing-image5733569 and https://www.alamy.com/resting-lioness-waving-away-flies-with-tail-lake-ndutu-tanzania-image246936327.html and https://www.alamy.com/female-lion-panthera-leo-waving-her-tail-unusually-high-image259098432.html and https://www.alamy.com/adult-lion-and-lioness-in-the-masai-mara-the-male-is-known-as-scar-or-scarface-due-to-damage-around-one-eye-and-he-is-the-dominat-male-in-the-pride-image211805367.html.

To be continued in part 2...

Ingresado el 30 de julio de 2021 por milewski milewski | 2 comentarios | Deja un comentario

28 de julio de 2021

Puzzle-patterns on felid undersides

The leopard (Panthera pardus) and the jaguar (Panthera onca) have camouflage colouration, and this includes their chests when they sit up: https://www.alamy.com/stock-photo-leopard-panthera-pardus-using-termite-mound-as-vantage-point-masai-32263955.html and https://adwimages.co.uk/wp-content/uploads/2019/01/Male-Jaguar_04.jpg.

By contrast, the chest of the closely-related snow leopard (Panthera uncia) is so pale and spotless that it seems to qualify as a pectoral flag: https://www.alamy.com/stock-photo-snow-leopard-panthera-uncia-adult-sitting-on-rock-captive-switzerland-78427404.html and https://www.alamy.com/close-up-of-snow-leopard-uncia-uncia-sitting-in-field-image281927193.html and https://www.123rf.com/photo_11673800_adult-snow-leopard-sitting-on-the-rock-looking-away.html and https://www.meowingtons.com/blogs/lolcats/photos-of-snow-leopards-biting-their-own-tails-are-everything.

Does this really make the figure conspicuous, or is it part of the camouflage against a mosaic of snow-patches among the rocks?

In the case of the tiger (Panthera tigris) there is a white, stripeless surface on the brisket, but on the sitting figure this is too low to catch the light: https://www.alamy.com/male-tiger-sitting-up-looking-intently-forwards-into-the-distance-image69669876.html and https://www.canstockphoto.com/close-up-tiger-52793325.html.

The cheetah (Acinonyx jubatus) is more similar to the tiger than to the snow leopard: https://www.alamy.com/stock-photo-female-cheetah-81726699.html. However, the long forelegs of the cheetah give it such an upright pose, while sitting, that the white, spotless brisket can look conspicuous in certain illuminations: https://www.alamy.com/cheetah-acinonyx-jubatus-image7758377.html. To the degree that the cheetah qualifies for a pectoral flag, this may serve in mimicry of the lion (Panthera leo), as I will illustrate in a forthcoming Post.

In the cases of leopard, jaguar and tiger, a different puzzle arises: the spotting or striping on the belly are so graphic that this seems incongruous with the countershading of the ground-colour in the same animals. Please see the photos below.

Here, my explanation would be that leopard and jaguar often hide in trees, the bold blotching on their bellies actually camouflaging them when viewed from below (e.g. see https://www.inaturalist.org/observations/9644461). But this leaves the tiger still a puzzle because this species seldom hides in trees.

Tiger: https://focusedcollection.com/465227104/stock-photo-tigers-captivity-panthera-tigris-corbetti.html and http://www.travelteamimages.com/big301600.html and https://www.dreamstime.com/stock-photo-tiger-lying-back-danger-image54978009 and https://www.dreamstime.com/stock-photo-tiger-lying-back-sweltering-hot-near-pool-image78296044 and https://www.dreamstime.com/high-angle-shot-white-tiger-lying-its-back-image192732848 and https://www.dreamstime.com/stock-photo-tiger-lying-her-back-berlin-zoo-germany-photo-made-image-you-see-partially-hidden-long-rock-mass-bed-image61100820

Leopard: https://www.istockphoto.com/photo/leopard-lying-on-its-back-gm89140038-2948132 and https://www.dreamstime.com/leopard-lying-its-back-grasslands-maasai-mara-kenya-leopard-its-back-image109364103 and https://www.shutterstock.com/image-photo/leopard-lying-on-his-back-sand-635997944 and https://imgur.com/gallery/U5DvgfV

Jaguar: https://i.redd.it/ph51eh8f60q41.jpg and https://www.agefotostock.com/age/en/details-photo/jaguar-lying-on-the-back-on-sand-bank-close-to-water-pantanal-brazil/N99-1977185/1

Cheetah: https://www.needpix.com/photo/1317451/cheetah-big-cat-wildanimal-wildlife-upsidedown-lying-back-tummy and https://www.dmuth.org/cheopard/a-typical-cheetah-lying-on-back/ and https://www.dreamstime.com/cheetah-lying-its-back-dry-grass-breeding-center-outside-johannesburg-south-africa-cheetah-lying-its-back-image142999287 and https://www.shutterstock.com/image-photo/cheetah-lying-on-back-south-african-427923721 and https://www.istockphoto.com/photo/a-picture-of-a-cheetah-lying-on-its-back-gm1143330626-307011984

Snow leopard: https://mltshp-cdn.com/r/1FAXX and https://www.alamy.com/snow-leopard-lying-on-its-back-image67311174.html and https://external-preview.redd.it/_-2UN1Vv94ulE-tEgJdBDZY9Mdltd7tcPJEe71Cm-ps.jpg?auto=webp&s=3c265930909e37de7e80c9d792b22671639f4684 and http://www.storytrender.com/93504/jazz-hands-stunning-snow-leopards-jump-caught-on-camera/

Ingresado el 28 de julio de 2021 por milewski milewski | 1 comentario | Deja un comentario

27 de julio de 2021

Further thoughts on the caudal flag of the leopard

In a recent Post (July 23, 2021), we discussed the possibility that the caudal flag (see https://www.inaturalist.org/observations/41144910 and https://www.shutterstock.com/nb/video/clip-30261376-female-leopard-walks-her-tail-curled-moremi) of the leopard (Panthera pardus) is indirectly adaptive to a habitat in which its enemies, the lion (Panthera leo), the tiger (Panthera tigris) and/or the spotted hyena (Crocuta crocuta, see https://www.youtube.com/watch?v=-rFubUfAFgM), are common.

We saw that one way to test this is by comparison with similar felid species in faunas depauperate in carnivores larger than the leopard. And indeed the puma (Puma concolor) and the jaguar (Panthera onca) do lack any caudal flag.

However, another test is possible in Sri Lanka, where a distinctive subspecies of the leopard (P. p. kotiya) is the top carnivore because of isolation on an island. The Sri Lankan leopard seldom bothers to hoist its prey into trees, eating on the ground.

There are many clear photos on the Web from Sri Lanka, because the leopard is unusually bold here. And these do indeed seem to show that the caudal flag is poorly-expressed compared to the African (P. p. pardus) and Indian (P. p. fusca) subspecies. In Sri Lanka the white underside of the tail seems inconsistent (e.g. see the third photo in https://www.inaturalist.org/observations/41229003), and curling up of the tail-tip seems to be infrequent.

The following video seems typical of the Sri Lankan subspecies: https://www.youtube.com/watch?v=jYO3obqi6H8. Compare it with these video from South Africa: https://www.youtube.com/watch?v=4zB7IIc21q0 and https://www.youtube.com/watch?v=_risCBZtIgc.

The following is also relevant to how the leopard manages its risk from superior carnivores in the African savannas.

R D Estes (1991), in The Behavior Guide to African Mammals, pages 367-368, points out that "a barking terrier can easily tree a leopard by daylight, and one even gave way to a yapping jackal (Bertram 1974)...that an animal as well armed and powerful as a leopard would surrender its own kills to a single (brown) hyena is somewhat puzzling." Estes elaborates on page 332: "a lone female (brown hyena) robbed a male leopard of the springbok it had just killed and when the leopard tried to reclaim it, chased it up a tree (Owens and Owens 1978). Yet the same (hyena) species keeps at least 200 m from lions on kills and allows 1/2 hour after the lions leave before moving in (Owens and Owens 1978)".

For proof that the leopard can be intimidated by a single brown hyena (Parahyaena brunnea), see https://www.youtube.com/watch?v=HW2OwVreINA.

Furthermore, the caudal flag of the leopard is larger, relative to body size, in females than in males, and probably also in juveniles than in adults.

These three lines of evidence - that the caudal flag is reduced in adult males and in all adults in Sri Lanka, and that in Africa the leopard sometimes gives in to inferior carnivores rather than risk attracting the lion or the spotted hyena - support the idea that the caudal flag signifies some sort of indirect appeasement.

Ingresado el 27 de julio de 2021 por milewski milewski | 6 comentarios | Deja un comentario