November 29, 2021

November 26, 2021

Explaining the extreme growth-form of Gardenia in the Serengeti

Gardenia volkensii grows as isolated large shrubs - one individual here and another last week - in open savanna in the Serengeti ecosystem. It would hardly be noticed were it not for its extreme sculpting by large mammals: and and and

It is hard to describe this growth-form but 'green coralloid', 'botanical statue' and 'compound bonsai' come to mind. Here we see a combination of gnarled stemwork (e.g. and tight-set foliage, making for a 'caulifoliar' plant.

Various species of woody plants are under pressure by large mouths, and various species of Gardenia occur in various other environments without being sculpted. So what is it about this species, in this ecosystem, that has led to a natural form of topiary?

Here is general information on Gardenia volkensii: and and,KwaZulu%2DNatal%20in%20the%20southeast and and and and

Gardenias are indigenous to Africa, Asia and Australia, and have become horticultural favourites. However, it seems to be only in the Serengeti that this genus is obviously shaped by large mammals.

Here are additional photos of G. volkensii in the Serengeti: and and and and and and and and and and

In trying to understand the niche of any organism, a challenge is to distinguish cause and effect, and to infer the central 'life-history strategy'.

So here are some observations and inferences applying to the genus Gardenia, the species G. volkensii, and the population in the Serengeti.

Gardenias are surprisingly prone to nutrient-deficiencies (as frequently noticed in horticulture, for plants that grow their stems, leaves and fruits slowly even under favourable conditions. Because such supplement-dependent plants would be expected to benefit from the nutrient-recycling by megaherbivores, their presence in the Serengeti ecosystem - albeit in small numbers - is unsurprising.

Instead of defending themselves with spines, gardenias tend to withdraw their foliage and stems. This is seen in extreme form in those species which remain largely underground ( and and and;jsessionid=1AF15650A3AD79CE5529E41C1B07E767?sequence=1 and

Although individual plants maintained in sculpted form are unlikely to produce fruits, it is noteworthy that
G. volkensii is unusual in its genus in being specialised for the sowing of its seeds by 'megafauna'.

Gardenias have technically fleshy fruits and the seeds are thought to be dispersed by mammals of various body-sizes
(e.g. see and and In the case of G. volkensii, the fruits are particularly large, leathery, long-lasting, and sturdily attached - and thus seemingly attuned to the 'megaherbivory' of the Serengeti.

These greyish fruits, when 'ripe' (and fragrant) seem designed mainly for the bush elephant (Loxodonta africana) and the eland (Taurotragus oryx). They are difficult to detach from the stems, and too big to fit into the gentle, pursed mouth of the Maasai giraffe (Giraffa tippelskirchi); they are likely to be out of reach of the hook-lipped rhino (Diceros bicornis); and they would probably be cud-chewed to destruction of the seeds by the greater kudu (Strepsiceros zambesiensis), which in any event is absent from this habitat in the Serengeti (see,when%20partially%20decomposed%20by%20fire.).

The bush elephant, when foraging on the foliage, is likely to break branches to some extent despite the flexibility of the wood of gardenias (see and Where free of such damage, the growth-form of G. volkensii is similar to and

The 'juvenile foliage' possessed by saplings of G. volkensii ( is a form of heteroblasty ( shared with various other woody plants. However, this species seems unusual in also possessing a second kind of heteroblasty at a different stage of its life, i.e. diminutive leaves crowded on to nodes, in response to repeated defoliation of old stems.

Thus an explanation may be found in the following combination of factors:

  • a particularly intense regime of pressures exerted by the bush elephant and the Maasai giraffe
  • in open vegetation where the few woody plants tend to be targeted repeatedly
  • partly owing to a bimodal climate (two rainy seasons each year) in which leaves tend to be present on this technically drought-deciduous plant for most of the time.

Because G. volkensii prefers nutrient-enriched soils, its leaves are somewhat attractive to folivores. Because it is 'hardwired' to grow slowly even in response to losses, it has a 'retractive' defence against defoliation; it may capitalise on faeces and urine but it is not stimulated by defoliation to replace its shoots rapidly. And because no member of this genus, as far as I know, has evolved spines, this species has found an unusual way to hug its leaves so close to its stems that plucking them is time-consuming for large mouths.

Based on the above, do readers share with me an impression that the genus Gardenia can be characterised by a combination of three modes: nutrient-inefficiency, slow growth, and spinelessness? And that this generic syndrome is in a way exposed in the sculpting of G. volkensii in the Serengeti ecosystem?

Posted on November 26, 2021 16:35 by milewski milewski | 7 comments | Leave a comment

Several remarkable photos of giraffes

The following show the pedal flag in Giraffa tippelskirchi more clearly than the mother plus three juveniles of the cheetah (Acinonyx jubatus) in the foreground, the spotted coats of which virtually hide them in plain sight. This photo illustrates a) the analogy between giraffes and big cats in inconspicuous colouration, b) the exceptional body size of giraffes as camouflaged megafauna, and c) the phenomenon of flagging in otherwise inconspicuous animals. The pedal flag of this species of giraffe is easy enough to spot once one has a search-image, but note that the cheetah too has flags: the white-and-black tail-tip (a caudal flag) and the dark back-of-ear (an auricular flag). The genitalia and horns show all of these individuals of G. tippelskirchi to be males, ranging from juvenile to adult. Body mass is about 45 kg for the adult female cheetah and about 500-1000 kg for these individuals of G. tippelskirchi.

At first sight the following seems to be just another photo of giraffes drinking. However, there is no water visible, because this is actually geophagy (earth-eating). Giraffes, like various other ruminants, sometimes supplement micronutrients by eating earth directly.

Two of the species of giraffes coexist with the eland (Taurotragus oryx), mature males of which are the most massive of antelopes. The following hint that giraffes are not only taller than the eland, but also more massive.

Giraffes are among the more sexually dimorphic of ungulates. However, the sexes remain rather difficult to tell when seen by themselves, because mature males retain approximately the same proportions as adult females and differ mainly in sheer size. The following is useful in showing them together in a way that reveals the difference in heights at the withers. In the first photo the male is adult but not fully mature.

The following illustrates the fact that females of giraffes usually forage with the neck not upright but horizontal. Whereas giraffes are thought of as having evolved to reach the treetops (and this is indeed true for mature males), a major adaptive advantage of the length of the neck is a lateral application of reach: across tangled or spinescent vegetation maintained at a convenient height by repeated pruning.

Posted on November 26, 2021 07:03 by milewski milewski | 2 comments | Leave a comment

November 25, 2021

The mystery of megafaunal microcamouflage

Everyone knows that giraffes and big cats are spotted, and zebras are striped.

And most would agree that these patterns function as camouflage in at least a loose sense.

However, how many have noticed that the disruptive markings in giraffes include spotting/striping too small-scale to make sense as camouflage?

The dark blotches/spots on the pelage of giraffes range in diameter from tens of centimetres to mere millimetres, despite the likelihood that both sizes will be viewed from similar distances by potential predators ( and

Under which circumstances could it possibly be true that the tiny spots - which are visible only at close range - on the forehead, temples and/or crown help giraffes to hide?

Forehead of adult female Giraffa tippelskirchi:

Temples and crown of mature male Giraffa tippelskirchi:

Temples of adolescent male Giraffa tippelskirchi:

Temples and crown of infant Giraffa tippelskirchi:

Temples and crown of mature male Giraffa camelopardalis:

Forehead of mature female Giraffa camelopardalis:

Forehead and temples of Giraffa reticulata:

In zebras, the striping on the forehead and temples is smaller-scale than that on the neck. However, the disparity is not as great and the fine-grained pattern is not as anatomically localised as in giraffes:

In big cats there is no particular disparity, because the spots are all of the same order of magnitude:

Panthera onca:

Panthera pardus:

Panthera uncia:

Panthera tigris:

One possible explanation is that the micro-spotting on the heads of giraffes functions not for camouflage but for individual recognition. This is not necessarily undermined by the fact that most individuals lack spotting on the forehead ( and, temples and crown.

This explanation would be in line with the general tendency for antelopes to be most individually variable in their colouration on the face, particularly the forehead (e.g. However, it is undermined by the observations that gregariousness in giraffes tends to be promiscuous, bonds among individuals seem to be weak, and the form of the horns and horn-tufts would seem sufficient for individual recognition.

Posted on November 25, 2021 22:41 by milewski milewski | 1 comment | Leave a comment

November 22, 2021

Precociality of the mane as a peculiarity of giraffids

Giraffids look odd compared to deer and bovids, with their long necks, long tongues, skin-covered horns, and extreme colouration ( and However, an unremarked oddness of giraffids is the precociality of their manes.

Manes occur on the nuchal region (i.e. the dorsal surface of the neck) in various mammals including Carnivora (, suids (, tapirs (, equids (, and various ruminants (,2403179/).

Various adaptive functions of manes remain to be studied, but an obvious one is to exaggerate body size, particularly in masculine display. Those ruminants in which both sexes have horns also tend to have nuchal manes, consistent with an antagonistic theme.

In the few ungulates in which hornless/antlerless females possess manes, these are raised in defensive anger (, again consistent with a theme of antagonistic exaggeration of body size.

These patterns do not apply to giraffes, in which the nuchal mane is proportionately largest at birth, smaller in adult females, and smallest in mature males.

Let us examine Giraffa giraffa giraffa for example:


adult females:

juvenile males:

mature males:

Turning to Giraffa tippelskirchi tippelskirchi, the following shows the differences between adult females and infants. Note that the mane becomes proportionately smaller with age but the occipital horn-tufts (see are proportionately smaller in infant than in adult:

Two other tracts of dorsal pelage are also proportionately largest at birth in giraffes.

The first is the main horn-tufts. The following show that, for example in Giraffa tippelskirchi, the main horn-tufts are proportionately larger in infants than in adult females: and and

The second is a caudal mane. Giraffes possess a slight mane on the tail-stalk, which is most distinct at birth: and and

The okapi (Okapi johnstoni, has a hardly-noticeable mane. However, in this species again the nuchal mane is fully developed at birth, disappearing in juveniles (

Posted on November 22, 2021 23:37 by milewski milewski | 3 comments | Leave a comment

November 21, 2021

Occipital horn-tufts: a previously overlooked feature of (certain) giraffes

It is well-known that the horns of giraffids are unlike those of deer or bovids, in being permanent, skin-covered, and adorned by tufts of hair instead of points.

So who would have expected zoologists to keep overlooking features as obvious - and with as much taxonomic significance - as secondary horn-tufts? And on animals with as high a profile as giraffes?

And yet these have indeed been overlooked.

Giraffes possess a main pair of horns, which are tufted in juveniles but become bald in adults, particularly males. However, they also potentially possess an additional pair of horns, located at the posterior edge of the cranium. This is the occipital part of the skull, just above the nape (e.g.

The occipital horns develop only in mature males, only in some of the species of giraffes, and only in some individuals. However, it is in their undeveloped (incipient), not developed, condition that the occipital horns bear small tufts, which can clearly be seen in many photos (e.g.

It is these additional horn-tufts that have escaped notice, as far as I know by everyone.

The occipital horn-tufts are located close to the top (distal extreme) of the mane. So in profile view they might be assumed to represent nothing more than the end of the mane. However, they are actually distinct in both position and tone ( Unlike the brown of the mane, the occipital horn-tufts are always blackish (

The occipital horn-tufts are most obvious in adult females, and they are clearest in Giraffa tippelskirchi. They are small in Giraffa giraffa, and vestigial or absent in Giraffa camelopardalis and Giraffa reticulata.


Because the occipital horn-tufts distinguish between different types of giraffes, they are useful taxonomically. They indicate that G. tippelskirchi is more closely related to G. giraffa than to G. camelopardalis, an affinity also borne out by pedal and laryngeal flags (see

One of the clearest illustrations on the Web is In this subadult female individual of Giraffa tippelskirchi, the occipital horn-tufts are almost as long as the tufts on the tips of the main horns.

However, even in females of G. tippelskirchi, the occipital horn-tufts are subject to individual variation: and and and

One of the peculiarities of the occipital horn-tufts is that they are neither masculine nor precocial.

In giraffes, the main horn-tufts are so precocial that they are present at birth, and are proportionally larger in infants than in adults. However, this does not apply to the occipital horn-tufts, as shown in the following of Giraffa tippelskirchi:

adult female with neonates/infants: and and and and and and

infants: and and and and

The above photos show that, although the occipital horn-tufts are present at birth, they are not proportionately large in infants in the way that the main horn-tufts are.

The following are further illustrations in Giraffa tippelskirchi:

second photo in

The following show that the occipital horn-tufts disappear in adult males, even in G. tippelskirchi:

adolescent male:

adult male:


The following show that, in G. giraffa, the occipital horn-tufts are usually small but are usually discernible by their blackness. The best-developed example I have found is the following:

adult females:

juvenile males:

The following show that the occipital horn-tufts are absent in adults of G. camelopardalis, even in females: and and and and and and,0,156 and


The only evidence of occipital horn-tufts in G. camelopardalis is a trace in some individuals:

adult females:



The following show hybrids between G. camelopardalis and G. reticulata: and and and and and


The following shows the absence of occipital horn-tufts in juvenile female G. reticulata:

Posted on November 21, 2021 23:24 by milewski milewski | 7 comments | Leave a comment

November 20, 2021

The giraffe of the Laikipia region of Kenya: time to correct its classification?

@michalsloviak @chewitt1 @johnnybirder @jakob @jwidness @bobby23 @dejong @maxallen @mikeloomis @kokhuitan @calebcam

The Laikipia region lies on a plateau just northwest of Mount Kenya. The protection of a form of Giraffa on privately-owned lands here has seemingly brought a success in conservation. However, re-examination of the identity of this form may be sobering.

The following map of the Laikipia region shows the complex patchwork of properties which are being managed partly for the conservation of wildlife:

In iNaturalist there are currently nearly 130 observations of Giraffa in the Laikipia region, most of which have been identified as Giraffa camelopardalis reticulata.

The following, just beyond the Laikipia region to its northwest, has yet to be identified but looks like Giraffa camelopardalis rothschildi:

The following from the western edge of the Laikipia region has been identified as Giraffa camelopardalis rothschildi:

The following, from the central parts of the Laikipia region, have ambivalent identifications:

The following has been identified as reticulata but fails to conform to that taxon:

Most or all of the other observations from the Laikipia region also fail to conform to reticulata with respect to at least two features. Firstly, the whitish 'matrix' is too broad on the distal part of the neck to fit reticulata. Secondly, the lower legs are pale, resembling rothschildi rather than reticulata.

I have seen no observations from the Laikipia region that conform fully to reticulata as typified in the region of Kenya farther to the east, in and near Samburu National Reserve (

What the above indicates is that the whole population of Giraffa in the Laikipia region consists of hybrids between reticulata and rothschildi. Some individuals resemble reticulata closely enough to be identified as such by experienced iNaturalists, but on closer examination even these show signs of hybridisation (see

An intermediate status makes sense given that the Laikipia region is located between the original ranges of reticulata and rothschildi. But which form inhabited the plateau at the time of European arrival?

I suspect that Giraffa was largely exterminated from the Laikipia region during the initial period of farming by European settlers, the surviving individuals being hybrids for reasons that remain to be established. With more recent conservation, the hybrid population seems to have spread, with the encouragement of landowners, to occupy most of the region.

What makes this ostensibly hybrid status all the more important is the growing realisation that reticulata and rothschildi belong to different species, not merely subspecies. If the population in the Laikipia region is an interspecific hybrid, its value for conservation is particularly questionable.

We need to search the literature to establish which form was originally indigenous to the Laikipia region. It cannot be assumed that this was a zone of natural hybridisation in the first place. It would also be helpful to document the degree to which the original population was depleted during the period when management was inimical to Giraffa.

We need to decide whether reticulata and camelopardalis are different species. In my view, one of the few reasons to doubt such taxonomic separation is the apparent fertility of the hybrids.

A survey would be helpful among landowners within the Laikipia region, based on questionnaires re the historical status of Giraffa on the various properties.

For now, I recommend that all current identifications of reticulata in this region should be changed to reticulata X rothschildi. If the species-distinction is accepted, the change should be to Giraffa reticulata X Giraffa camelopardalis rothschildi.

The current assumptions give a misleadingly encouraging impression of the overall status of reticulata (see Some 60% of what have been counted as reticulata Kenya-wide occur in Laikipia county, which is only part of the Laikipia region ( and This means that the true remaining population of unhybridised reticulata in Kenya is possibly only a third of what has been published recently.

There is no cause for complacency in the conservation of subspecies reticulata, partly because it is now as rare (in unhybridised form) as the West African Giraffa camelopardalis peralta, and partly because it may deserve the attention of a full species.

Posted on November 20, 2021 22:24 by milewski milewski | 4 comments | Leave a comment

November 19, 2021

Reframing the reticulated giraffe

Which iNaturalists would identify the following as the reticulated giraffe? This Post may help you to correct some misperceptions.

Everyone knows that a diagnostic feature of the reticulated giraffe (Giraffa reticulata) is the conversion of the normal blotchiness of giraffes into a network effect ( and and

However, now that we have examined flags ( and pallor (, we can re-characterise the reticulated giraffe from a broader perspective.

Here we have the most uniformly-coloured and most thoroughly camouflaged of all giraffes ( and

The caudal flag is the same as in other giraffes, the tail-tassel being black:

Here is a reminder of what a laryngeal flag looks like:

There is no laryngeal flag in Giraffa reticulata:

Giraffa reticulata also lacks the pale and/or spotless patches on the cheeks that are seen in other giraffes.

There is no pedal flag in Giraffa reticulata:

Many photos do show lower legs pale enough to qualify as a pedal flag, but these are from the Laikipia region of Kenya ( and from zoos ( and, where there has been hybridisation with Giraffa camelopardalis.

The following unhybridised individual shows the maximum paleness on the feet in Giraffa reticulata, which does not qualify as a pedal flag:

Here is a reminder of what an ilial flag looks like: and

There is no ilial flag in Giraffa reticulata:

The form of the forehead and rostrum is distinctive in both sexes of Giraffa reticulata. The bump on the forehead is relatively abrupt. In mature males, the rostrum remains free of enlargement by ossification:



Compare the latter with mature males of Giraffa tippelskirchi, in which not only the forehead bump but also the rostrum become ossified:

Another difference between Giraffa reticulata and the hybrid population in the Laikipia region is that, in the latter, some individual mature males develop pallor on the head (e.g.

Having begun this Post with a test, let me end it with another one along similar lines. iNaturalists, how would you identify the following?

Posted on November 19, 2021 21:22 by milewski milewski | 0 comments | Leave a comment

The puzzle of conspicuous pallor in a Sahelian giraffe, part 2

To appreciate fully the meaning of the pallor in G. c. peralta, it may also be useful to review the incidence of anomalous darkness in giraffes - which is of a different kind.

In Giraffa giraffa in particular, there is a pattern of sexual dimorphism in which fully mature males - which can weigh up to 1.5 tonnes as opposed to the average 0.8 tonnes of adult females - darken in conjunction with producing strong odours from skin glands ( This change is unpredictable, individually variable, and not necessarily permanent.

The darkness and smelliness of males at the peak of breeding condition detract from their camouflage, but pose no particular puzzle. This is because a) it is normal for males, particularly in sexually dimorphic species, to trade off security for sexual advantage, b) the self-advertisement of males need not compromise the camouflage of females and juveniles, because gregariousness is loose in giraffes, c) males may possibly be less vulnerable than females to predation, and d) darkness, although somewhat conspicuous by day, remains inconspicuous by night or in twilight.

The following illustrations of masculine darkness suggest that this pattern applies to only a limited extent in some of the species and subspecies of giraffes:

Giraffa giraffa giraffa

Giraffa tippelskirchi

Giraffa reticulata

Giraffa camelopardalis camelopardalis

Giraffa camelopardalis rothschildi

In the case of G. c. peralta, the blotches do seem to darken in mature males (see e.g. However, this is not enough to give the figure a dark aspect overall, because a) the matrix remains the same as in females and immature males, and b) the head does not darken.

Is it not apparent in this dual context that - relative to both other ruminants of the Sahel/Sahara and other forms of giraffe across Africa - any tendency towards conspicuous pallor in giraffes shows a basic adaptive shift? And is this not a significant exception to any generalisation that the colouration of giraffes is designed for camouflage?

Posted on November 19, 2021 05:12 by milewski milewski | 3 comments | Leave a comment

November 18, 2021

The puzzle of conspicuous pallor in a Sahelian giraffe, part 1

Does anyone doubt that, in general, the colouration of giraffes is a form of camouflage?

The flags which I have described (see hardly negate this generalisation, because they are subsidiary features.

However, one subspecies of giraffe has overall colouration so conspicuously pale that it does seem to mean a partial negation ( and

I refer to Giraffa camelopardalis peralta ( and and of the western Sahel.

The particular pallor of Giraffa camelopardalis peralta is owing mainly to the breadth of the whitish 'matrix' among the blotches (see and

This differs from any pale overall effect in the form of giraffe inhabiting the edge of the Namib desert in southern Africa, which is owing mainly to fading of the blotches themselves and does not particularly affect the head or legs (Giraffa giraffa angolensis, see and

The following photos of the most pallid individuals show how the camouflage effect has been compromised in Giraffa camelopardalis peralta in its current habitat. Although a corollary of the pallor is that the auricular and pedal flags are reduced, the caudal flag is if anything enhanced, because the tail-tassel remains black in all individuals.

Can it not be said that G. c. peralta has, in evolutionary terms, switched from inconspicuous colouration to conspicuous colouration? The mechanism has been a quantitative shift (mainly an encroachment of the pale matrix relative to the blotching), but the effect seems qualitative.

If so, this seems convergent with the conspicuous pallor of three other gregarious ruminants of the southern fringes of the Sahara, as exemplified by the following views of Oryx dammah: and

Oryx dammah (, Addax nasomaculatus and Nanger dama ruficollis ( all inhabited the vicinity of the Sahara, with O. dammah coexisting in the Sahel with giraffes (including G. c. peralta), A. nasomaculatus penetrating the Sahara itself, and N. d. ruficollis living in the eastern Sahel (where the local form of giraffe was not as pallid). In converging on a pattern of conspicuous overall pallor, these species set an unique pattern among the arid-adapted ungulates of the world.

I realise that:

  • arid-adapted reptiles, birds, and small mammals tend to be pallid as a form of crypsis in the pale environments of deserts, particularly sandy deserts;
  • there is seasonal variation in the colouration of A. nasomaculatus and possibly also the other two bovids referred to here; and
  • hippotragins and gazelles tend to be adaptively conspicuous even in savannas, which can be partly explained by the futility of trying to hide as gregarious animals in the open.

However, ruminants in the southern African deserts and semi-deserts ( and lack the relevant pattern of colouration. In the degree of their pallor, our three bovids seem to have adapted in convergent ways to the particular conditions of the Sahara and its southern edges.

Seen in this context, does the pallor of G. c. peralta not seem to be part of a regional faunistic pattern?

The following illustrate the pallor of our three bovids, and the adaptive convergence that this represents.

Oryx dammah:

Addax nasomaculatus:

Nanger dama:

to be continued...

Posted on November 18, 2021 11:28 by milewski milewski | 3 comments | Leave a comment