Journal archives for December 2021

December 01, 2021

An odd case of scenery shaped by natural mega-masculinity

Many thanks to @zarek for help with this Post.

Everyone knows that flat-topped trees occur in African savannas, as epitomised by the Serengeti ecosystem.

However, how many realise that one of the most photogenic of these would not be flat-topped but for planar pruning by giraffes and the bush elephant (Loxodonta africana)? And that this has a sexual dimension?

Balanites aegyptiaca ( and and has a flat top the lower margin of which is always at precisely the height of maximum reach of fully mature male giraffes ( and and and

Vegetation characterised by flat-topped B. aegyptiaca is particularly associated with the Maasai Mara National Reserve in southwestern Kenya, which constitutes the northernmost part of the Serengeti ecosystem (e.g. and and and and

However, it is recorded also from semi-arid central Kenya, where a different species of giraffe occurs: and

In giraffes, foraging postures are surprisingly dimorphic along sexual lines. Whereas adult females forage mainly with the neck horizontal, mature males forage mainly with the neck upright ( and and

The following shows that, even when stretching vertically, females of the Maasai giraffe (Giraffa tippelskirchi) would be far too short to reach the 'browse-line' set by mature males on B. aegyptiaca:

What this means is that a conspicuous feature of the Serengeti is maintained quasi-horticulturally by mature male giraffes. Here, B. aegyptiaca is shaped at the scale of the scenery by not only megaherbivory but also fully erect masculinity.

The following, marginally influenced by megaherbivores at the northern edge of the Serengeti ecosystem, shows the form of the crown of B. aegyptiaca free of recent pruning: Where megaherbivores are absent, the following is representative:

The following, of ecologically similar Balanites maughamii in and near Kruger National Park in South Africa, confirm that the crown in this genus is not intrinsically broader than it is deep: and and

Even in the Maasai Mara National Reserve, B. aegyptiaca would not be flat-topped were it not for a fortuitous limitation on the height of the trees. This is shown by the following of B. maughamii in Kruger National Park, which grows tall enough to give some depth to the crown above any 'browse-line':

The following show that females of the Maasai giraffe can reach the crown of B. aegyptiaca only when the trees are still young: and and

The 'browse-line' is about 6 metres above ground level (see and and Balanites aegyptiaca thus provides a natural scale in any photo containing flat-topped individuals of this species (e.g.

The site-specific context of flat-topping in B. aegyptiaca is shown by comparison with a far more widespread flat-topped tree, the acacia Vachellia tortilis (

Vachellia tortilis extends from the range of the reticulated giraffe (Giraffa reticulata) in northeastern Africa ( and and to southern Africa, where Balanites is present (albeit not flat-topped) in the form of the species B. maughamii (

The difference between these flat-tops is that the shape of the crown in certain subspecies of V. tortilis is intrinsic, i.e. genetically 'hardwired', and produced independently of any pruning by megaherbivores.

This is easily proven by many photos showing individuals of V. tortilis close to giraffes but so tall as to be completely out of reach of their foraging (e.g. and and and and and and and and and and

The following gives a misleading impression that the upper surface of this well-grown sapling of V. tortilis is being shaped by the Maasai giraffe (of which a mature male is pictured): In fact this shape is spontaneously adopted in V. tortilis regardless of pressures by either giraffe or elephant.

The following show how the crown of B. aegyptiaca is shaped as soon as it overtops mature males of the Maasai giraffe: and and and and and

Posted on December 01, 2021 09:04 PM by milewski milewski | 47 comments | Leave a comment

December 04, 2021

Giraffes as tree-shunners

Giraffes are associated with trees.

These, the tallest of animals, eat the foliage of trees. Mature males habitually forage with the neck upright, reaching to nearly 6 meters above ground. And the colouration of giraffes camouflages them among trees.

Keeping this in mind, look at the trees in the following.




DEEP IN THE SAHARA (Niger, Libya and Algeria)


SERENGETI PLAIN (Serengeti National Park/Ngorongoro Conservation Area, Tanzania)

Do the above not clearly show that various species of giraffes occur far from trees?

Giraffa giraffa angolensis extends to the tropical margin of the Namib desert, and is often photographed in vistas that are bare of even shrubs.

Giraffa giraffa giraffa is at home in the southwestern Kalahari (, where the mean annual rainfall of only 15 centimeters is in line with the driest parts of the Australian continent.

Giraffa reticulata is restricted to semi-deserts in northeastern Africa, where trees occur patchily.

Giraffa camelopardalis is thought to have occurred widely across the Sahara when this area was semi-arid, before about 5,000 years ago.

Even the equatorial Giraffa tippelskirchi tippelskirchi is often photographed in grassland. And this includes the treeless Serengeti Plain itself.

So - beyond reminding us that everything is relative - where does this leave our notion that giraffes are associated with trees?

Well, giraffes are paradoxical in a way: categorically dependent on trees but at the same time quantitatively avoidant of trees.

An explanation lies in the following:

  • giraffes depend on a nutrient regime that tends to be associated with semi-aridity,
  • a combination of nutrient-richness and drought tends to keep the vegetation low and open,
  • adult females of giraffes, which experience particular nutritional demands while producing milk, tend to forage with the neck horizontal, rather than upright, and
  • the most important food-plants tend to be tall shrubs, and saplings suppressed by hedging at 2-3 meters high.

Because nutrient-richness tends to correlate with drought, the trees actually attractive to giraffes tend to be sparsely distributed and hardly taller than large shrubs.

Now consider the other side of this picture.

Giraffes, in contrast to their success in 'scrubby' vegetation at the edges of deserts, have failed to penetrate the greener savannas. This means that they are naturally absent where most trees occur. Compare with

Beyond the equatorial forests that nobody expects to be inhabited by giraffes, most of the trees in Africa form 'moist-dystrophic' woodlands and savannas, which are equally unsuitable. The most extensive savannas in Africa - naturally empty of giraffes - are miombo woodlands in the southern hemisphere ( and their equivalents in the northern hemisphere (e.g. and and and Please see

All of these occur under rainfall conducive to leaching of nutrients, and on substrates (e.g. derived from granitic rocks) that are nutrient-poor in the first place. Giraffes are naturally absent from most of the woodlands and savannas because most trees - in Africa and on other continents alike - are malnutritious and/or too high-crowned for even the tallest ruminants to reach or suppress.

In order to understand why most trees are malnutritious for giraffes, it helps to realise that:

  • giraffes are ruminants (cud-chewers),
  • all ruminants depend on quality rather than quantity of food,
  • as the largest ruminants, giraffes have exceptionally rapid metabolism and growth for their body size, and thus
  • giraffes depend on a certain minimum concentration of nutrients - unmet by most trees - in their food.

The soils nutrient-rich enough to produce palatable trees for giraffes tend to be confined to dry climates because:

  • one of the most important ecological factors is leaching of nutrients by rain (, and
  • this is so important that nutritious foliage is more likely to be available on deep sand under a dry climate than on ostensibly fertile loam under a rainy climate.

For a further understanding of the ecological principles, see:

Does the following not emerge as a pattern more informative than any simplistic association with trees?

Giraffes depend not on the crowns of trees as much as on large shrubs, plus like-size saplings of drought-tolerant, relatively nutritious trees, suppressed and maintained at convenient height by repeated pruning ( and and

Posted on December 04, 2021 09:00 AM by milewski milewski | 25 comments | Leave a comment

December 07, 2021

Giraffes: how to find my various Posts


  • reticulata

  • hybridisation




  • flags

  • faces/heads

  • camouflage/conspicuousness

  • hues


  • horn-tufts

  • manes


  • general

  • Balanites aegyptiaca

  • Gardenia volkensii

Posted on December 07, 2021 02:21 AM by milewski milewski | 0 comments | Leave a comment

New views on species/subspecies/hybrids: where to find my taxonomically relevant Posts

In my Journal I have at various times pointed out new subspecies, suggested splitting existing species, criticised existing classifications, or provided photo-guides to subspecies within a given species. The following is a guide.

Canidae (dogs)

  • non-wolf ancestor of domestic dog

  • distinctiveness of dingo

Phacochoerus (warthogs)

  • extinct species in South Africa

Camelus (camels)

  • hybridisation of species

Giraffa (giraffes)

  • reticulata as a separate species

  • hybridisation reticulata X camelopardalis rothschildi

  • occipital horn-tufts as taxonomic indicator

Oreotragus (klipspringers)

  • tyleri as not widespread in Namibia

  • oreotragus of South Africa and Namibia as a distinct species

Connochaetes (wildebeests)

  • mattosi as a distinct subspecies

Sylvicapra (bush duiker)

  • photo-guide to subspecies

Philantomba (blue duikers)

  • species-distinctions

Antilopinae (gazelles and relatives)

  • golden springbok as throwback

  • subspecies in springbok

  • Iranian gazelle as distinct species

Nemorhaedus (gorals)

  • photo-guide to species (REQUIRES UPDATING)

Equus (asses, zebras and horses)

  • domestic subspecies of Asian wild ass

  • tail as subspecific feature in Equus hemionus

  • failure to breed back phenotype of extinct quagga

  • distinctiveness of subtropical plains zebra

Posted on December 07, 2021 07:18 AM by milewski milewski | 0 comments | Leave a comment

A first theory on the adaptive colouration of giraffes, part 1

Giraffes are familiar in a larger-than-life way, and recognised by their colouration second only to their peculiar shape.

So iNaturalists might reasonably suppose that the adaptive colouration of giraffes has long since been solved by zoologists.

However, such is not the case. Instead this question continues, after centuries, to lie on the table, free to be picked up by any enquiring mind.

As far as I know, no scientist has even attempted to explain the colouration of giraffes coherently. I attribute this lapse to:

  • a view that colouration, because it defies statistics, is beyond rigorous science,
  • preoccupation with social behaviour and genetics,
  • discouragement by the contradictions and inconsistencies that appear as soon as the subject is tackled, and
  • a deep ambivalence between faith in adaptation (by natural selection) and assumption that many features are accidental.

So, on the downside, this topic is unfashionable in our current scientific scene. But, on the upside, anyone can tackle it without special funding, access to a laboratory, or even leaving home.

I studied giraffes in the wild for years (mainly on the Athi-Kapiti plain in Kenya, 1985-1988), so intimately that I actually developed an allergy to some substance in their fur. I have also collected what is perhaps the biggest archive of hard-copy photographs of giraffes in the world, starting with pamphlets and postcards when I was a schoolboy more than half a century ago.

So here is an attempt at a theory of adaptive colouration of giraffes.

First, some principles applying to ungulates and carnivores:

  • these mammals fail to see most hues because of their dichromatic (, motion-sensitive visual systems,
  • darkness and paleness, and particularly the contrasts between them, are much of what adaptive colouration is about in ungulates (including giraffes) and their non-human predators,
  • human eyes tend to mislead because we are too sensitive to hues (other than ultraviolet) and not sensitive enough to motion - particularly in dim light,
  • we should therefore view colour photos and videos as if converted to black, white, and shades of grey, while at the same time
  • we should remember that even slight/partial motion can annul the most elaborate camouflage.

In summary so far, the most important features of adaptive colouration are dark/pale contrasts at various scales - which are as visible to humans as to the ungulates and carnivores.

Additional principles include the following:

  • colouration functions differently depending on scale/distance and night vs day,
  • most animals combine conspicuous and inconspicuous features, striking a compromise between the need to hide from predators and the need to communicate with their own kind,
  • adaptive pressures for inconspicuousness are likely to be strongest for infants, and weakest for mature males of sexually dimorphic species,
  • dark/pale effects can result from not only pigmentation/depigmentation but also antisheen/sheen, and
  • conspicuously pale or dark features can be expected to be located on particularly mobile body-parts, e.g. the ear pinnae, tail-tassel and feet.

to be continued...

Posted on December 07, 2021 11:44 PM by milewski milewski | 0 comments | Leave a comment

December 08, 2021

A first theory on the adaptive colouration of giraffes, part 2

(writing in progress)

For the purposes of this theory I assume that there are three species of giraffes, namely a nothern/western one (Giraffa camelopardalis), a northeastern one (Giraffa reticulata), and an eastern/southern one (Giraffa tippelskirchi/giraffa).

I have chosen the following photos to show these at their most different:




These species differ so much in colouration that one can generalise explanations to giraffes only in the case of certain minor features shared by them all, e.g. the tail and the ear pinnae.

It seems obvious that the spotting/blotching of giraffes reduces their conspicuousness to predators, by means of disrupting the outline of the figure. However, various caveats deserve explanation and some of them, in certain subspecies, are important enough to challenge this explanation categorically.

In approximate order of importance, the caveats include:

  • many individuals of Giraffa camelopardalis peralta are so pallid, owing to the predominance of the pale matrix over the spotting/blotching, that camouflage is an unconvincing explanation for this subspecies at any scale, distance, or illumination,
  • the form of the spotting/blotching varies so much among the species of giraffes that categorically different patterns occur in e.g. Giraffa reticulata vs e.g. Giraffa giraffa,
  • although giraffes do remain stationary at times when alarmed, they tend to give themselves away by peering over the tops of tall shrubs/short trees,
  • no comparably large-bodied mammals feature spotting/blotching,
  • the tail, when swished vs insects, is conspicuous enough to draw attention - at least by day - in situations where the animals might otherwise be overlooked,
  • all three species occur partly in vegetation so open that the whole notion of camouflage-colouration seems inappropriate.

In reticulata, the spotting/blotching is so modified that has become a different pattern, i.e. a network of pale superimposed on a darker 'matrix'. What is matrix in camelopardalis has become non-matrix in reticulata. These patterns cannot simply be equated.

Giraffa reticulata is ostensibly the simplest species to analyse, because:

  • it lacks subspecies,
  • its pattern is the most uniform of all the species/subspecies of giraffe, and
  • it lacks all conspicuous features other than the black tail-tassel and the pale posterior surface of the ear pinnae.

However, two basic problems remain in reticulata, making an overall function of camouflage unconvincing:

  • the network effect is too different from spotting/blotching to e assumed to function similarly, and
  • its habitat includes such low, open vegetation that it is difficult to portray it as being able to hide by means of camouflage.

to be continued...

(writing in progress)

Posted on December 08, 2021 10:48 AM by milewski milewski | 18 comments | Leave a comment

December 15, 2021

Do oxpeckers provide overall benefit to giraffes?

Everyone knows that giraffes (Giraffa) and oxpeckers (Buphagus, have an intimate relationship (e.g. see and and and and and and and

However, how many realise that it remains unsure whether giraffes get any overall advantage from the relationship?

On the upside is that oxpeckers remove ticks and other ectoparasites ( and But on the downside is the risk of oxpeckers betraying the whereabouts of giraffes to potential predators.

Because it is difficult to weigh a chronic mitigation against an acute exacerbation, the net benefit for giraffes remains difficult to assess.

Oxpeckers utter various rattling vocalisations, in:

  • social communication within the species,
  • alarm vs their own predators, and
  • surrogate alarm on behalf of their megafaunal hosts.

Readers can hear examples in the following:

Oxpeckers sometimes behave (e.g. taking refuge behind the mane of giraffes) as if alarmed on their own behalf by the approach of potential predators such as the human species (e.g. see This is puzzling because the predators involved are extremely unlikely to target the birds in the first place. And it is not necessarily the case that oxpeckers, when on giraffes, simply maintain silence until giving the alarm on behalf of their hosts.

There is evidence that oxpeckers do aid the hook-lipped rhino (Diceros bicornis) by announcing the approach of humans ( and However, rhinos have exceptionally poor eyesight whereas giraffes have exceptionally good eyesight (

Giraffes have such extreme visual advantages that any augmentation of their vigilance by oxpeckers is questionable.

(As a thought-provoking digression, please see the sheer difference in the sizes of the eyeballs in Nobody needs doubt that the eyesight of oxpeckers can be as good as that of giraffes, but is it not remarkable that this depend so little on size?)

Instead, the birds' calls - uttered for whichever reason - may possibly draw the attention of predators to individuals or small groups of giraffes otherwise fairly concealed by trees.

So, the problem resolves partly to an apparent conflict between two adaptive values:

  • that of the colouration of giraffes, which hypothetically camouflages them, and
  • that of their association with oxpeckers, which hypothetically undermines this camouflage.

This puzzle is unlikely to be solved soon, because relevant data are hard to collect and the behaviour of oxpeckers towards potential predators is complex and seemingly inconsistent.

In the meantime, I have gleaned the following information and illustrations from the Web, for the general interest of iNaturalists. and and and and



Posted on December 15, 2021 06:28 PM by milewski milewski | 10 comments | Leave a comment

December 16, 2021

Are the social flags of giraffes activated in infants?

The adaptive colouration of giraffes is largely inconspicuous but includes some conspicuous features, presumably in aid of social communication.

I have described these in previous Posts (e.g., pointing out that they vary individually and among the various species and subspecies of giraffes.

However, the question remains of whether the conspicuous features function at the stage of infancy.

Infants might be expected to be particularly inconspicuous because of vulnerability to predators and frequent separation from their mothers. In giraffes, however, infants older than one week hardly hide, instead becoming precocially social with their age-group in open vegetation (

Furthermore, the necks of infants tend to be held erect and the main horn-tufts - which are present at birth and particularly large in Giraffa tippelskirchi - seem to function as adornments rather than disguise.

For these reasons, adaptive colouration is ambivalent in infants of giraffes.

Here I examine caudal, auricular, laryngeal, and pedal flags by means of the photos available.


The black tail-tassel is proportionately small at birth in all species and subspecies of giraffes (e.g. see This suggests that a caudal flag is not fully functional in infants.


Giraffa tippelskirchi tippelskirchi

Giraffa giraffa giraffa

The above evidence seems ambivalent, because the posterior surface of the ear pinnae is not consistently whitish in infants.

However, we have previously seen that the conspicuousness of the auricular flag is owing to a combination of depigmentation and sheen. Even in adults, the auricular flag may falter when the angle of illumination fails to give a sheen effect. The following are examples in Giraffa tippelskirchi: and and

I tentatively conclude that an auricular flag is present in infants of all forms of giraffe.


Giraffa tippelskirchi tippelskirchi

Giraffa tippelskirchi thornicrofti

Giraffa giraffa giraffa

As in the case of auricular flags, a laryngeal flag seems ambivalent in infants. However, the reasons are partly different because this flag depends not only on sheen but also on dark spotting of the adjacent surface of the neck. This spotting tends to be pale in infants, suggesting somewhat delayed development of a laryngeal flag.


Giraffa tippelskirchi tippelskirchi
scroll to the third photo in

Giraffa camelopardalis rothschildi

A pedal flag seems to be fully developed in infants of Giraffa tippelskirchi, and more obviously precocial than the other flags. In the case of Giraffa camelopardalis there is ambivalence, because the lower legs do not seem as pale in infants as in adults.

An ilial flag is restricted to Giraffa giraffa giraffa and seldom clearly shown in photos. However, the following suggests its presence in at least some individual infants:

In summary: in giraffes, the colouration of infants is so precocial that all the flags seem at least nominally present. There is scant evidence that infants rely on camouflage any more than adults do.

Posted on December 16, 2021 08:41 AM by milewski milewski | 2 comments | Leave a comment

December 17, 2021

Unexplained tropical hues in giraffes

In a previous Post (, I pointed out that tropical - and particularly equatorial - species and subspecies of small ruminants in Africa tend to differ from their extratropical relatives in a particular aspect of colouration.

Whereas extratropical forms tend to be plain brownish, related tropical forms tend to be differentiated into bright hues (particularly reddish or yellowish) vs dull hues (greyish). There is individual variation within a given population, but the trend is noticeable overall.

As a reminder for readers, this difference is exemplified by the following carefully-chosen photos within a single species of klipspringers (Oreotragus):



Giraffes are extremely large ruminants, but they show a similar pattern of differentiation. Again, this is individually variable but noticeable overall. The most illustrative comparison is that between Giraffa tippelskirchi (tropical) and Giraffa giraffa (extratropical) - which are so closely related that they may be subspecies of a single species.

Giraffa tippelskirchi tippelskirchi

Giraffa giraffa giraffa

In this species/superspecies of giraffe (i.e. tippelskirchi/giraffa), the upper lip tends to feature a fawn-coloured longitudinal strip, while the cheeks tend to be grey. But it is in the tropical form that the differentiation on the basis of hue is most likely to be distinct.

The tropical differentiation of hues in giraffes is most obvious on the face. However, it can also be seen on the neck and legs in some individuals, e.g. and and and and

It remains possible that, in the eyes of the animals as opposed to the human observer, the tropical forms are as plain as the extratropical forms. Since ruminants and the carnivores that prey on them do not see hues in the same way as humans, we cannot assume that the patterns shown here have adaptive value.

However, are the differences not food for thought in the context of differences in the quantities and qualities of sunlight at tropical vs extratropical latitudes?

Posted on December 17, 2021 12:46 AM by milewski milewski | 3 comments | Leave a comment

December 20, 2021

Auricular flags in ungulates

(writing in progress)

Auricular flag in Equus quagga boehmi

The following is one of the few photos of the eland (Taurotragus oryx) showing its (subtle and slight) auricular flag:

The following is an unusually clear illustration of an auricular flag in the impala: The back of the head is more conspicuous in the impala than in other antelopes, partly owing to the dark distal third of the ears. What is less well-known is that this is offset, when the light is at a certain angle, by a sheen that converts the normally fawn fur of the back of the crown to whitish. The dark/pale flag thus achieved is unique to the impala. The sheen is easily observed in the field but has seldom been photographed well. Some indication can be seen in

The following shows an auricular flag of the puku (Kobus vardoni): This is similar to that of the impala.

(writing in progress)

Posted on December 20, 2021 11:54 PM by milewski milewski | 1 comment | Leave a comment