Journal archives for September 2021

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

Explaining the carnivoragenic suppression of wild ungulates pointed out by the late Valerius Geist

Valerius Geist (1938-2021), a pioneer in the biology of ungulates (see, died recently ( It seems appropriate to discuss a basic puzzle he pointed out, about the relationship between predators and prey.

See concerning the incidence of wild ungulates in the taiga biome of Eurasia and North America.

The following is worth reading carefully, and pondering deeply:

Extensive areas of the taiga biome seem 'naturally' empty of ungulates despite having vegetation similar to those areas supporting the moose (Alces alces), the caribou (Rangifer tarandus), and wild sheep (Ovis spp.). Because the wolf (Canis lupus) and the brown bear (Ursus arctos) are common in these empty areas, Geist suspected that there has been a carnivoragenic (my word, not his) depletion of the populations of the ungulates. The wolf and the brown bear are such efficient predators that they can reduce moose, caribou and wild sheep to the point of rarity.

Geist asserted that a key to restoring the ungulates is human control of the wolf in particular.

Geist hinted at a rationale in which the omnivorous brown bear, sustained mainly by non-ungulate foods, can naturally exert so much pressure on infants that moose, caribou and wild sheep fail to reproduce year after year over extensive areas.

However, the obvious question arises: what sustains the wolf - which is not omnivorous - in empty areas of the taiga biome?

If Geist had an answer to this, I did not see it in

I suggest that the answer is the rodents (e.g. Urocitellus, see,no%20longer%20be%20retained%20as%20a%20single%20genus, and Marmota, see and lagomorphs (Lepus spp.) which during the Holocene have been the dominant consumers of green foods in the taiga biome. These rodentiforms are adapted to the extremely seasonal availability of greens by a combination of hibernation and fecundity which allows them to repopulate rapidly after episodic events such as wildfires. The ungulates have a limited advantage in their mobility, but in their overall energetic role in the taiga ecosystem they are subordinate to rodentiforms.

The wolf may prefer ungulates to rodentiforms as prey, but it can sustain its populations on a staple diet of rodentiforms.

With this piece of the puzzle filled in, the whole rationale seems to make sense: the human species has the option, by means of suppressing the populations of wolf and brown bear, of promoting the ungulates. Would it be simplistic to suggest that, in the taiga biome of the Holocene, we have basically two alternative 'settings' with respect to the ungulates: carnivoragenic suppression or anthropogenic promotion?

Posted on September 02, 2021 20:33 by milewski milewski | 6 comments | Leave a comment

September 03, 2021

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

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

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 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 | 1 comment | Leave a comment

September 06, 2021

Adaptative colouration in gorals

There are three species/species-groups of gorals (Nemorhaedus): western (goral, bedfordi), central (baileyi), and eastern (griseus, caudatus). These differ little in adaptive colouration if one ignores reddish hues which are probably invisible to ungulates and carnivores.

The colouration of gorals is inconspicuous (e.g. and, being a combination of cryptic and disruptive. This inconspicuousness is adaptive in reducing the chances of being spotted by predators.

However, there are several patterns which can be conspicuous at close range when in motion, and in some species or individuals of gorals these qualify as flags.

Flags are designed to be overlooked at distances relevant to scanning predators, but to become noticeable at relatively short range once secrecy is unnecessary: for example, in informing a stalking predator that it has lost the advantage of surprise, or to inform a companion of direction of locomotion while foraging.

In gorals, the parts of the body which have modest-size or at least residual patterns of dark/pale contrast - making them candidates for flags - are the throat ( and, the fore feet ( and, and the tail/buttocks ( In the genus in general, these remain at the edge of being noticeable enough to communicate signals to conspecifics and/or detected predators.

The frontal flag consists, in both sexes, of a large pale patch on the throat in conjunction with the pale upper lips, and in contrast with the dark rhinarium. It is activated by e.g. the movement and sound of alarm-snorting.

The frontal flag is well-developed in Nemorhaedus goral ( and and some individuals of Nemorhaedus griseus ( and Nemorhaedus caudatus (, and poorly-developed in Nemorhaedus baileyi (

The pedal flag is located more on the fore than the hind feet, and consists mainly of pale pasterns in contrast with dark carpals. It is activated by foot-stamping in alarm, and by walking.

The pedal flag in Nemorhaedus goral, Nemorhaedus griseus and Nemorhaedus caudatus varies individually rather than among species. The dark feature on the front of the fore leg can be centred below ( and or above the carpals ( and and and

The following show the individual variation in the configuration of the pedal flag within Nemorhaedus caudatus: and and;jsessionid=DBBB086BBDC9E4C88C1467650A95118E?page=ViewImageData&service=external&sp=27963 and

The caudal flag consists of the dark of the tail-tassel next to a small area of pale on the buttocks, or (in some individuals of Nemorhaedus caudatus) the white of the tail-tassel plus that on the buttocks (see and It is activated by the infrequent flicking of the tail (e.g. see, or by the loose, passive movement of the tail while running in the case of N. caudatus.

In Nemorhaedus goral the pattern is vestigial, which means that most individuals lack any caudal flag ( and

The following show the pattern in: Nemorhaedus griseus ( and and and, Nemorhaedus caudatus ( and and and, and Nemorhaedus baileyi ( and, and ostensibly the same species in winter coat:

I have not seen enough photos to be sure about seasonal changes. However, the following suggest that the conspicuousness of the front-of-ear differs between the summer coat and the winter coat: and and

Nemorhaedus baileyi is so nondescript in summer coat ( and that a more apt name than 'red goral', in adaptive terms, would be 'monotone goral'.

In the following I have assembled the clearest photos of each species/species-group.

Nemorhaedus goral

Nemorhaedus griseus

Nemorhaedus caudatus

Nemorhaedus baileyi

Posted on September 06, 2021 05:39 by milewski milewski | 0 comments | Leave a comment

September 07, 2021

The Emperor Has No Stripes: retrieving the phenotype of the quagga will need some uncomfortable realism

The quagga (Equus quagga quagga, is the extinct southernmost subspecies of the plains zebra.

It differs from the adjacent, surviving subspecies (Equus quagga burchellii) in having reduced striping on the body, a predominantly dark tone on the head, neck and torso, and a short forelock ( and and and

Several decades ago, selective breeding was started with the goal of retrieving the phenotype of the quagga from a carefully-chosen, minimally-striped founder stock of Equus quagga burchellii ( and and

Although the project continues, a spectacular result has already been achieved after five generations: an unprecedentedly pale phenotype ( and and

This interim result resembles the extinct quagga in only one way: the minimal striping on the legs, torso, shoulders and haunches. The forelock and the rest of the mane remain as long as in Equus quagga burchellii, and in the case of the overall tone of the head, mane, neck, and torso there is regress instead of progress, because the interim result is paler than in E. q. burchellii and therefore far paler than in the extinct quagga.

Overall, this is a case of one step forwards, one step back.

Despite the incongruous pallor of the interim result, the project has been hailed as already successful from all sides (e.g.

The celebration seen in all the commentary on this topic is premature and indicates a level of cognitive dissonance which is now the main problem for the project.

In order to correct course, the breeding will in future have to select for darkness on the head, neck and torso ( However, it is difficult to envisage how this can be done without 'going backwards', i.e. without inadvertently undoing the hard-won reduction in striping.

The particular challenge: the more that selection has reduced the striping, the more it has also produced an overall depigmentation. So far, it seems that if one starts with Equus quagga burchellii and breeds selectively, one cannot reduce the striping without also precluding the necessary darkening of the ground-colour between the stripes on the torso, and the necessary widening of the dark stripes on the neck and mane. Please note that the problem of darkening consists of two components at apparent odds with each other.

Hence the real - but largely unacknowledged - disappointment at this stage: whereas the extinct quagga was (except for the conspicuously whitish fore legs) the darkest of all species/subspecies of zebras, the interim result is by far the palest of all zebras.

Because this interim result is in an important way the opposite of the one desired, no amount of satisfaction with the minimisation of the striping will ultimately be able to sweep the problem under the hide, as it were.

The Quagga Revival Project may yet surprise us with some way of keeping the striping minimal while a) darkening the ground-colour on the torso, and simultaneously b) widening, on the neck and mane, the dark stripes to the point of switching the effect to pale striping on a dark ground-colour (see and And it may eventually focus on the problem of the forelock.

However, the deliberate course-correction needed for this will certainly be challenging. Does the project have the leadership, enthusiasm and funding to overcome a 'reality check' of this gravity?

Posted on September 07, 2021 10:29 by milewski milewski | 7 comments | Leave a comment

September 08, 2021

Capricious subspeciation in the plains zebra, part 1

The plains zebra (Equus quagga, occurs from temperate South Africa, across the equator, to Ethiopia, a distance of about 5000 km (

This is one of the most deeply subspeciated animals on Earth. The various subspecies look like different species, partly because their adaptive colouration seems to vary not just in degree but in kind. And there is no general conformity with geographical clines.

In this Post I focus on a particular puzzle in this variation: the lack of latitudinal correlation.

A reason to expect a latitudinal pattern in the pelage of the plains zebra is that this species does change in body size in the expected way: body mass was up to perhaps 400 kg farthest away from the equator, compared with perhaps 200 kg near the equator (in western Somalia). However, in other respects the variation seems to make little sense.

At first glance, the striping is least distinct in the southernmost subspecies and becomes progressively more distinct northwards. However, this breaks down on closer scrutiny.

Consider, in no particular order:

Two northern subspecies, in northern Uganda (E. q. borensis) and eastern Kenya (E. q. isabella), have short manes ( A central subspecies (E. q. crawshayi) has a long mane ( However, there is no latitudinal pattern because moderately short manes occur in both the southernmost subspecies of temperate climates (E. q. quagga: and the main equatorial subspecies (E. q. boehmi).

Shadow striping occurs in E. q. boehmi from central Kenya to Ethiopia ( and It virtually disappears in E. q. boehmi in Tanzania to Zambia (, and then becomes extremely well-developed in E. q. chapmani of southern Africa ( In the southernmost subspecies (E. q. quagga), shadow striping cannot be distinguished from a general darkening.

Intensity of striping reaches its acme in central and northern Mozambique. However, the variation defies latitudes: going east to west about latitude 15 degrees South from Mozambique through eastern Zambia ( and western Zambia ( to south-central Angola ( and finally southwestern Angola ( takes us in at least four stages from narrow, black-and-white stripes to wide stripes on a fawn ground-colour and with shadow stripes.

In the Gorongosa-Marromeu area, just west of the mouth of the Zambezi River, there is a switch over a short distance from subspecies chapmani, with its wide and incomplete stripes, to the population with the most intense striping of all, that of the Rift Valley in Gorongosa National Park (see and scroll within These forms are so different that they look like different species. If we accept that they are both subspecies of the plains zebra, it is mystifying that, despite living so near to each other, they have avoided intergradation.

Given all this capricious variation, one begins to see the true complications in any attempt to retrieve the phenotype of the extinct quagga (see my latest Post) by the selective breeding of the adjacent, surviving subspecies.

Equus quagga quagga ( had gleamingly unstriped legs. However, in other respects it was not just an extrapolation of the trend established from Equus quagga chapmani ( to Equus quagga burchellii (

The ways in which E. q. quagga was unprecedented included: inexplicably short in the mane, and inexplicably dark on the neck and torso. Furthermore, this darkness was not merely the acme of a southwards trend towards shadow striping. Instead, on the torso it was achieved by an obscure blend of darkened ground-colour and anastomosis of the striping ( And on the neck it was achieved by an unprecedented widening of the dark stripes, to the point that - unique among the subspecies - the ground-colour was relegated to narrow 'unstripes' (see illustrations in my last Post).

to be continued...

Posted on September 08, 2021 17:08 by milewski milewski | 7 comments | Leave a comment