Journal archives for September 2021

September 03, 2021

Bipedal versatility in ruminants, part 2

In all of the ruminant families other than deer, the only photographic evidence of free-standing bipedally is in a few species of bovids: the gerenuk (Litocranius walleri), the dama gazelle (Nanger dama), and goats (Capra spp.).

The gerenuk is unlike any deer in being specialised for bipedal foraging. The dama gazelle has an unusually long neck and legs but is not as specialised as the gerenuk ( The gazelles Ammodorcas clarkei and Gazella arabica ( and are probably also capable of free-standing bipedally. All of these species have habitats drier than that of any deer.

The gerenuk is in some sense 'the exception that proves the rule'. Free-standing bipedally in deer is seasonal and occasional, and associated with generalised form and diet. By contrast, in the gerenuk it is associated with an extreme specialisation: a diminutive muzzle picks out a staple diet of small leaves among the spines of acacias ( Any quarreling among females of the gerenuk is enacted on all fours, merely by making poking gestures with the head.

There is one spillover of free-standing bipedally into social/sexual behaviour in the gerenuk. Estes (1991, page 89) states: "Gerenuk copulation is the most spectacular example of the unique antilopine technique: the 2-m-tall male walking bolt upright with forelegs dangling behind the moving female and managing intromission without falling over backwards" (see

What emerges is that, overall, the gerenuk lacks the bipedal versatility seen in deer.

In the case of goats, the situation is ambivalent. Firstly, foraging bipedally has been photographed only in the case of the domestic species. Secondly, free-standing bipedally in wild goats has only been photographed in males, where it is part of masculine rivalry and a prelude to horn-butting. I infer that in most cases the posture is maintained only briefly before plunging down and forwards.

Capra ibex

Capra walie

Capra hircus

Litocranius walleri

Nanger dama (see above)

Madoqua spp.

Several species have been recorded foraging bipedally, but no photo shows free-standing

to be continued...

Posted on September 03, 2021 21:37 by milewski milewski | 2 comments | Leave a comment

Bipedal versatility in ruminants, part 1

Ruminants (deer, bovids, musk deer, giraffes, pronghorns and chevrotains) stand and run on all fours. However, some species are able to free-stand bipedally to forage or to quarrel, and it is here that intriguing patterns await discovery by naturalists.

I refer to standing upright with the back vertical but without propping the forelegs on branches or other supports.

What is obvious from perusal of photos on the Web is that ruminants differ categorically in their bipedal versatility. I have seen thousands of photos of, for example, the impala (Aepyceros melampus), without finding any evidence of free-standing bipedally. By contrast it takes only a few minutes to find such evidence in the case of deer (Cervidae) resembling the impala in body size and proportions.

In this, part 1, I show that many species of deer are bipedally versatile. In part 2, we will see that other families of ruminants lack this versatility except for a few genera of bovids. In part 3, I will offer some explanations of these findings.

The following show that a dozen or more species of deer in at least eight genera, including both sexes, are able to free-stand bipedally. The photographic evidence is clear for both foraging and social antagonism. Free-standing bipedally while quarreling is seen not only in females but also in males while the growing antlers (still in velvet) risk permanent damage from any attempts to butt each other.

In quarreling while free-standing bipedally, a typical action for deer is to flail the fore hooves downwards threateningly. The mouth is held horizontal and the ears are turned back. This suggests that the muzzle-ring functions as a buccal semet in this context; and in the relatively few species possessing suitable patterns on the ears there is also evidence of auricular semets.

Alces alces

This species sometimes forages by standing upright (, but I do not know whether this includes free-standing bipedally

Rangifer tarandus

I suspect that this species forages for lichens in trees during winter by free-standing bipedally, but I have yet to find photos

Odocoileus virginianus

Odocoileus hemionus

Dama dama

Cervus canadensis

Cervus elaphus

Cervus nippon

Rusa unicolor

Elaphurus davidianus

Axis axis

Muntiacus reevesi

to be continued...

Posted on September 03, 2021 09:46 by milewski milewski | 0 comments | Leave a comment

September 09, 2021

An unexpected convergence in colouration between giraffes and zebras

What do you notice about these two photos? and

Take it for granted that giraffes (Giraffa spp.) and zebras (four species of Equus) are similar: large ungulates with extreme colouration.

And that giraffes are by far the largest land animals with camouflage colouration, while zebras are so striped that the adaptive value of their colouration has been a major puzzle.

It seems safe to assume that, in both giraffes and zebras, the main functions of the overall colourations are to make the figures inconspicuous in some sense.

So, what in the above photos do I find remarkable?

Well, we have seen in previous posts about the moose (Alces alces) and various other ungulates, as well as various carnivores, that it is normal for largely inconspicuous animals to possess flags.

Flags are relatively small-scale patterns of colouration, subsumed within the overall colouration as long as the figure is stationary. However, they are large and dark/pale enough to become conspicuous once the animal moves in certain ways.

The intriguing convergence between giraffes (all species, both sexes, and both juveniles and adults) and zebras (albeit only one species, and only certain subspecies/individuals) is: both have unmarked, gleamingly pale ears, constituting auricular flags, when viewed from behind.

The auricular flags of giraffes and zebras are activated when the animals walk away intermittently. In this perspective there is a noticeable contrast between the whitish back-of-ear and the rest of the colouration, which is further accentuated by the normal movements of the ear pinnae. Such flagging presumably aids gregariousness because it makes it easy for individuals to keep track of each other's movements by means of the briefest glance. It also informs companions of any sudden attentiveness of an individual turning its eyes and ears towards something suspicious, thus promptly communicating any alarm.

The following, of Giraffa tippelskirchi tippelskirchi, shows how thoroughly camouflaged giraffes can seem by virtue of their colouration:

However, in all giraffes the back-of-ear is exempt from spotting: and

Furthermore, the short fur on the back-of-ear seems to possess a sheen, making it even more eye-catching in certain lights. The following show illuminations where this sheen effect is not apparent: and and

The following show how conspicuous the auricular flag of giraffes can be even at considerable distance: and and and and

Turning to zebras:

In three of the four species of zebras, the back-of-ear has complicated colouration:

Equus grevyi: and and and

(the following nicely compare the front- and back-of-ear of E. grevyi: vs

Equus hartmannae: and

Equus zebra: and

However, in several subspecies of the plains zebra (Equus quagga) there is a tendency for the back-of-ear to be mainly whitish (e.g. E. q. burchellii and

The basic pattern in this species, which varies according to subspecies and individual, is In several subspecies this can hardly qualify as an auricular flag because the whitish feature is too small.

However, in two northern subspecies (E. q. borensis and E. q. isabella) the whitish area covers most or all of the back-of-ear, and the ear pinna is unobstructed because the mane is particularly short ( and and and and and and and

In several other subspecies, there is individual variation:

Equus quagga burchellii and and and

Equus quagga chapmani and and and

Equus quagga boehmi and and and and and

The only extant subspecies in which I have yet to see any individual with an auricular flag is E. q. crawshayi ( and and

In the case of the extinct quagga (E. q. quagga) nobody has examined the museum specimens for this, but my impression from photos is that there was no auricular flag ( and If so, this is yet another way in which the extinct quagga was not merely an extrapolation of the trend in colouration from E. q. chapmani to E. q. burchellii.

Posted on September 09, 2021 22:36 by milewski milewski | 3 comments | Leave a comment

Capricious subspeciation in the plains zebra, part 2: a new suggestion re the extinct quagga

What if inappropriate founders were chosen for the Quagga Revival Project, based on incorrect assumptions?

Please see my last two Posts.

The idea behind the Quagga Revival Project has been that any capacity for re-expression of the phenotype of the extinct E. q. quagga would likely occur in the geographically adjacent subspecies, namely Equus quagga burchellii. And so individuals were chosen and captured from populations of E. q. burchellii, starting the process of selective breeding.

However, E. q. burchellii has an oddly disjunct distribution: Zululand vs northern Namibia-southwestern Angola. These areas are 1600 km apart, and the southeasternmost sites are twice as far from the equator (30 vs 14 degrees South) as the northwesternmost sites. What if these two populations are significantly different genetically, with that in Zululand having the most in common (albeit not necessarily expressed in the wild phenotype) with the extinct quagga?

In order to see that northern Namibia might have been an unsuitable source of founders - because it is so far from the distribution of the extinct quagga - we must for a moment discount any taxonomic controversy.

Whether we call the northern Namibian population burchellii or not, this population apparently extended northwards to about 14 degrees South, in southwestern Angola (see file:///C:/Users/Antoni%20Milewski/Downloads/Beja2019_Chapter_TheMammalsOfAngola%20(1).pdf). If so, then capturing individuals in the Etosha area, as was done for the Quagga Revival Project, meant resorting to a gene-pool living up to 2000 km from the nearest population of the extinct quagga.

Whether we call the Zululand population E. q. burchellii or not, this form lived at most a few hundred km from the nearest population of the extinct quagga, i.e. at least four times closer.

This is what I suspect.

Before European arrival, there were five genetically different types of the plains zebra in southern Africa south and west of the Zambezi River. Their ranges (see were:

1) Western Cape, Eastern Cape and the southern part of Northern Cape provinces, extending to southern Free State province (extinct quagga),

2) northern Free State province to northern Kwazulu-Natal province,

3) Mpumalanga and Limpopo provinces and northwards as far as northern Botswana (nobody quibbles with calling this E. q. chapmani),

4) North West province at the southern edge of the Kalahari (an extinct population from which the type specimens for both burchellii (see and and its junior synonym antiquorum were collected), and

5) Namibia, extending to southwestern Angola.

Of these, the one geographically closest to the extinct quagga was 2).

If it were up to me to start the Quagga Revival Project from scratch, I would capture founders only in Zululand, and I would prioritise individuals with the darkest ground-colour rather than individuals with minimal striping on the legs and hindquarters. I would then breed selectively for overall darkness before trying to reduce the striping.

Posted on September 09, 2021 00:22 by milewski milewski | 1 comment | Leave a comment

September 04, 2021

Bipedal versatility in ruminants, part 3

Why is there such a great difference in bipedal versatility between deer and bovids?

In general, deer tend to live as one species (or two if sufficiently different in body size) per type of environment. They have broad niches in this context. By contrast, bovids tend to live in species-rich communities, in which the species share a given environment by partitioning the resources. One of the ways that food is partitioned in bovid communities is by height above ground.

Let us take Kruger Park in South Africa as an example. The ruminants most comparable with deer in this savanna are, from smallest to largest, the steenbok (Raphicerus campestris, and and and, the impala (Aepyceros melampus,, the greater kudu (Strepsiceros strepsiceros, and and and and, and the southern giraffe (Giraffa giraffa).

Each has a typical height-zone for foraging, particularly in the dry season when food is scarcest (, and none tries to extend its foraging height by standing bipedally, even with the fore legs propped on branches. There are categorically no photos of such postures.

In other words, bovids tend to be specialised in terms of the range of heights at which they forage, whereas deer tend to exploit the widest height-range allowed by their bipedal versatility. This applies even to the gerenuk, because this species not only forages bipedally, but is far more specialised for doing so than is any deer.

Given this versatility, it is understandable that deer also use free-standing bipedally in their social behaviour, in a way never seen in e.g. steenbok, impala, greater kudu or other bovids - including the gerenuk.

Wild goats are more rock-adapted than any deer; the scaling of steep rocky slopes may require postural flexibility which has been retained and perhaps enhanced through domestication. However, what wild goats share with deer is that they tend to be the only ruminants in the environments they inhabit, which means that they tend to forage over a wide height-range by means of some degree of bipedal versatility.

Posted on September 04, 2021 15:57 by milewski milewski | 0 comments | Leave a comment

September 18, 2021

The domensal dog that is the dingo

Europeans first exploring Australia were surprised by more than the hopping of kangaroos.

They found that the largest non-human predator on this continent-size island is was a canid merely the size of a coyote (Canis latrans) or a terrier.

This means that the dingo was uniquely small for the largest carnivore in a continental fauna.

Even more surprisingly, they later found that the dingo - far from emulating kangaroos in being unique to Australia - is shared with Thailand ( and, Borneo (, Sulawesi, New Guinea and other peninsular/insular parts of southeast Asia and Indonesia (e.g. see

The dingo seems to have been brought to Australia only 5,000 years ago, despite the human species having arrived 60,000 years ago and the dog having been domesticated in Eurasia 15,000 years ago.

Adding to the puzzle, the dingo differs from both the wolf (Canis lupus) and the domestic dog (Canis familiaris) without being intermediate between them ( For example, the dingo shows colour-polymorphism including a black-and-tan morph ( and never recorded in the wolf.

Most significantly, the dingo cannot satisfactorily be described as domestic, or feral, or wild.

How can we integrate these surprises into a coherent interpretation of the true nature of the dingo?

Perhaps a key is to recognise a new category, which in my latest Post I have called 'domensal'.

The aboriginal people of Australia, in general, neither kept the dingo captive, nor controlled its reproduction, nor used it to perform services such as hunting. Even after being hand-reared, the dingo remains disobedient. It refuses to take orders from even those human individuals whom it treats as kin and to whom it is loyal.

Instead, the essential relationship was as follows.

The dingo was attracted to human camps mainly for edible refuse and consumable human faeces. The people sometimes transferred infants ( and and from dens to their camps, hand-rearing them as children's pets.

Once adult, the dingo was free to leave human company in order to breed with mates of its own choice like a wild animal.

This means that, in its own way, the dingo paralleled my description of the Maasai donkey (in my latest Post, of September 17, 2021).

The equid carried burdens in return for the benefit of protection from wild predators in corrals devoted to domestic ruminants.

By comparison, the canid afforded a supply of pets in return for the benefit of using food-waste at human camps.

Perhaps as a result of the relaxation of selective breeding by humans, the dingo parallels the Maasai donkey in having wild-type colouration. In both cases, remarkably few individuals have the irregular and asymmetrical features of colouration typical of domestic species (

Both the Maasai donkey and the dingo have small bodies, which means that their demands on resources are limited. Throughout its range except for the seasonally cold southeast of Australia, the dingo has average adult body mass of only 10-15 kg, compared to 20-30 kg for the wolf in similar climates.

The dingo has for several thousand years been the only non-human predator capable of hunting adult kangaroos, and has large jaws for its body size. However, it has not compensated in body size to emulate the wolf, instead remaining more similar to a jackal.

The recent arrival of the dingo in Australia (and, probably, New Guinea) is consistent with its ecological niche not being unique to Australia. Across a wide spectrum of island-like situations, the local people have not, for various cultural reasons, considered canids to have utilitarian value. The result is that in Asia/Indonesia the dingo is essentially a street-dog, owned by nobody but in the long term tolerated in certain villages.

Does all of this add up to the following characterisation?

The dingo is the canid most adapted to a domensal niche, which it has managed to occupy over a wide range of climates, human population densities, and human economic systems. Like the Maasai donkey, the dingo is domesticated enough to be non-threatening to humans, and useful enough to be tolerated, but maintains the ambivalent relationship mainly for certain benefits afforded passively by the humans.

Posted on September 18, 2021 05:59 by milewski milewski | 4 comments | Leave a comment

September 11, 2021

Finding expression in the face of the chacma baboon

The chacma baboon (Papio ursinus) is the largest (see and most southerly of monkeys. It is also exceptionally well-photographed, allowing us to illustrate its facial expressions.

There are at least four ways in which the face of the chacma baboon is so unlike the human face that we find difficulty in reading its expressions.

Males of the chacma baboon can fang-bare like carnivores ( However, the usual facial expression of masculine defensiveness and assertion is an exaggerated yawn, showing the pale eyelids ( and and and This is similar to a 'displacement activity' but serves to show the size and sharpness of the canines as a polite warning.

In the chacma baboon the expression of fear or appeasement is a grin/grimace (adult female: and

Whereas eye movements are extremely expressive in humans, they are extremely inscrutable in the chacma baboon. This is possibly because in humans status is gained mainly by sharing information, whereas in the chacma baboon status is gained mainly by withholding information ( and

The chacma baboon does possess pale ocular features, but these are located in keeping with a theme of non-divulgence and an avoidance of staring.

Firstly, adults of both sexes possess pale patches of fur on the otherwise bare rostrum, which seem designed to distract viewers from the eyes themselves. These can perhaps be thought of as 'false eyes' (see and and and and

Secondly, the pale eyelids are shown to express antagonism in both sexes. This can be the equivalent of a frowning stare but with the eyelids rather than the eyeballs doing the staring, or it can be a signal of appeasement. The half-closed eyes are accompanied by either raised eyebrows (assertive?) or flattened ears (submissive?). The following show the cringing expression in adult females: and

The 'neonatal makeup' of the chacma baboon ( and involves both a dark/pale contrast (blackish fur on the crown vs pale bare skin on the face of the newborn) and conspicuously reddish hues (particularly on the ears). This vivid colouration evokes the protective instinct of adults and juveniles so strongly that infants need no other facial expression for the first months of their lives.

Posted on September 11, 2021 02:56 by milewski milewski | 6 comments | Leave a comment

September 01, 2021

Colouration of antlers and horns in ruminants, part 1

Antlers, borne by deer (see, and horns, borne by bovids, are made of bone and keratin respectively. These materials tend to be medium in tone, neither noticeably dark nor noticeably pale. As a result, in most ruminants the conspicuousness of the outgrowths depends on their size and shape rather than their colouration.

However, three exceptions spring immediately to mind in which antlers or horns have conspicuously pale surfaces. The resulting displays seem to have different functions: intraspecific (social/sexual) advertisement in deer and a warning to predators in a bovid.

The antlers of the moose (Alces alces) are not only unusually palmate but also unusually pale. This makes them more showy as adornments. The bleaching is not owing to weathering because it appears as soon as the velvet is rubbed off.

Comparison with the fallow deer (Dama dama) suggests that the effect in the moose is adaptive and not merely a result of the boniness of antlers. This is because here we have adornments which are palmate without being pale: and and and and

The antlers of several genera of deer have conspicuously pale points, again functioning probably only intraspecifically. Deer tend not to defend themselves from predators by means of their antlers, and even during masculine conflict the method is mutual pushing rather than impaling (e.g. see Therefore the accentuation is probably for adornment rather than for warning.

The wapiti (Cervus canadensis) is a prime example: and However, even the fallow deer: has conspicuously pale brow-tines:

Among bovids, the most extreme case of conspicuous colouration of horns is the muskox (Ovibos moschatus). However, this conforms less to social advertisement and more to warning colouration directed at non-human predators, today reduced to the wolf (Canis lupus).

Odd-looking horns grow in both sexes of the muskox. The horn-shaft is gleamingly pale, becoming dark only at the sharp tip itself. Adult males additionally have a broad boss at the base of each horn, which is pale against the background of dark fur and oddly free of fur in this otherwise shaggy species. Although females lack bosses, they mimic them by means of a gleamingly pale patch of fur in the corresponding position on the forehead, a pattern that is all the more significant given the remarkably inconspicuous colouration of the ears. Furthermore, this pale patch is precocial, appearing in juveniles long before the horns become noticeable.

Males of the muskox fight with their horns, not by hooking but instead by charging and mutually butting with the blunt bosses (see For this reason, it cannot be ruled out that the conspicuous pale of the bosses functions intraspecifically. However, what is more likely is that the entire show - of bosses, hooks, and boss-mimicking fur - constitutes a collective display to predators, and the only example of aposematic colouration in any ungulate.

The horn-shaft of the muskox is shaped more suitably for defence than in other ruminants, in its hooked orientation forwards and outwards. However, it is too narrow, particularly in females, to be sufficiently conspicuous in its own right. Hence, I would argue, the bosses are incorporated into the display, and the display of the bosses is in turn made partly deceptive for aggregate effect.

The muskox forms tight ranks when threatened (see, a defensive specialisation unmatched in any other ungulate. This provides an opportunity for a collective show to which even the unarmed juveniles can contribute, and which reminds would-be predators unfamiliar with the muskox that the horn-tips, although small relative to the shaggy bulk of the animals, are lethal.


Posted on September 01, 2021 10:14 by milewski milewski | 3 comments | Leave a comment

September 02, 2021

Colouration of antlers and horns in ruminants, part 2

On the human body, we daily observe that keratin, the substance of horns, can be either pigmented (dark hair) or translucent (fingernails). It should therefore not surprise us to find that bovids show adaptive flexibility in the tone of their horns.

Here I focus on the saiga antelope (Saiga tatarica,, the prime example of a bovid species with pale horns, and on the bontebok/blesbok (Damaliscus pygargus), the prime example of a bovid species in which subspecies vary noticeably in the tone of the horns despite the horns remaining similar in size and shape, and showing minimal sexual dimorphism.

The saiga antelope is closely related to gazelles, but unlike any gazelle has horns so depigmented that they are about as clear as human fingernails. The horns accordingly look 'flesh-coloured'.

This is puzzling in terms of evolutionary adaptation. The saiga antelope is extremely peculiar in its nasal anatomy (uniquely proboscis-like, particularly in males, see and its running gait (camel-like pacing instead of cantering), but it is hard to link these peculiarities rationally to the translucency of its horns.


The bontebok (nominate ssp. pygargus) and the blesbok (ssp. phillipsi) have horns approximately similar in shape to those of the saiga antelope, but in females as well as males. These two subspecies occupied separate parts of South Africa, differing mainly in the boldness of their overall colouration. Who would have predicted that members of a single species would differ so much in the tone of their horns?

As in the saiga antelope, this has yet to be explained in terms of adaptation.

For Damaliscus pygargus pygargus see

For Damaliscus pygargus phillipsi see

Posted on September 02, 2021 03:32 by milewski milewski | 2 comments | Leave a comment

September 05, 2021

The basic nature of elephants, part 1

Which of the following is more apt, about elephants?

Elephants are so massive that they need their extreme body shapes in order to function at such sizes


Elephants are specialists in bodily shape-shifting, which happen also to be massive.

We can call the first the graviportal hypothesis, and the second the morphodynamic hypothesis.

In the graviportal hypothesis, bodily shape-shifting is necessitated by extreme body size. In the morphodynamic hypothesis, there is merely correlation, not cause, because the shape-shifting of elephants - as their main specialisation - would remain even if body mass was only a few hundred kg.

Elephants have columnar legs which locomote forwards in only one gait, the amble. They can catch up to a fleeing human at a speeded-up walk, but are technically unable to run because there is always at least one foot touching the ground (see

At the same time elephants are more posturally versatile than most ungulates (see, particularly in being able to free-stand bipedally (see and and and and and and and

Elephants have a short neck, compensated for by a long, remarkably elastic proboscis (is this fake? in which the nose and upper lip, seamlessly fused, have been jointly modified into the equivalent of a combination of hose and versatile limb.

Elephants have a voluminous, spongy cranium which functions as a buoy when the animal is immersed. They are exceptionally capable swimmers among land mammals (see and

Elephants have the vulva shifted farther forward, relative to the anus, than in any other land animal (see and, and the penis reaches the vagina by being extremely long and flexible (see and

Elephants have a tail which is even longer than it looks (see because it is partly buried in the buttocks (see and and

Note that not just the proboscis, but also the vagina, penis and tail of elephants are extremely elongated.

There are at least three immediate reasons to question the graviportal hypothesis.

Firstly, an extinct perissodactyl (see was more massive than elephants but not correspondingly modified.

Secondly, the largest specimens of living rhinos (e.g. Ceratotherium simum) and hippopotamus (Hippopotamus amphibius) overlap elephants in body mass but lack any of the specialisations listed above. In particular, they remain able to use similar running gaits to medium-size ungulates (e.g. see and and

Thirdly, elephants inhabiting marine islands retained their bodily proportions despite becoming diminutive (see and and and

to be continued...

Posted on September 05, 2021 05:04 by milewski milewski | 0 comments | Leave a comment