Journal archives for October 2021

October 05, 2021

The bambis, part 6: a selection of the most revealing photos of klipspringers

For many large mammals, the photographic record is just sufficient to give an idea of what the species looks like. However, some species - such as klipspringers - are so attractive and photogenic that there are now enough photos to reveal subtleties and details.

I have scoured the Web, looking for photos that happen to reveal more than the photographers focussed on. In no particular order, here are my current choices for little-known aspects of klipspringers.


Everyone knows that klipspringers are the ungulates most specialised for rocky terrain, but how many realise that their walking gait (even on flat ground) is correspondingly extreme? And that they can climb trees?

Whereas antilopins - like most ruminants of open vegetation - amble, klipspringers follow a different sequence of movements of the limbs. Klipspringers are both the most extreme cross-walkers among ruminants and the only 'hyper-unguligrade' mammals on Earth. Like most ungulates, they walk on their claws, but unlike all other ungulates they walk on the tips of their claws (

Compare the steenbok (Raphicerus campestris, and Kirk's dikdik (Madoqua kirki, with the following of klipspringers: and and and and

If you find yourself cross-eyed at the positions of the walking limbs, try again with the mountain gazelle (Gazella gazella), which - like the bambis above but unlike klipspringers - ambles:

The order in which klipspringers move their limbs is awkward in the sense that the hind foot risks bumping against the fore foot. However, what these rupicolous antelopes are specialised for is a combination of 'tiptoe' and stability. Cross-walking is the most stable of walking gaits, helping to explain why monkeys and the koala, adapted to walk along the limbs of in trees, cross-walk even on flat ground...

...which brings us to klipspringers in trees: and and and and .


Everyone knows that the migrations of large ungulates in the Serengeti attract the world's best photographers of wildlife. However, how many realise that the local subspecies (schillingsi) of klipspringer has been excellently portrayed as a result? and and


The following seems to illustrate the fact that some females, as well as all males, grow horns in subspecies schillingsi of the Serengeti:


The auricular flag in klipspringers is precocial ( The conspicuous pattern is already present in juveniles, and the ear pinnae are already fully grown when the horns are still short: and

In the Cape klipspringer, the ear pinnae are similarly precocial in size, but there is no auricular flag in either adults or juveniles: This would be one of the main reasons to reclassify the Cape klipspringer as a separate species, not just a subspecies.


Everyone knows that klipspringers are more-or-less monogamous, and some may know that they 'kiss' with their preorbital glands. But how many realise that the married partners do not groom each other?

Instead, klipspringers have an odd relationship with starlings (belonging to the same family as oxpeckers), which remove ticks from the head: and and and and[Augrabies%20Falls%20National%20Park]/2/.

Animals as small-bodied as klipspringers are not attractive to oxpeckers, and it is surprising that klipspringers are attractive to Onychognathus spp. ( Perhaps this reflects the peculiar nature of the fur (see below) in some way (

Even a bird as different from oxpeckers as the familiar chat ( participates in the de-ticking of klipspringers:


Everyone knows that the tail is hardly noticeable in klipspringers, but how many realise that it is proportionately longer than in most ruminants adapted to the cold parts of the Northern Hemisphere (e.g. chamois, ibex, wild sheep, moose, wapiti, caribou, roe deer, pronghorn)?

In klipspringers, the tail is not rudimentary, it just lacks a tassel ( And its colouration is inconspicuous - which is consistent with a shift of function from the caudal flagging so common among ruminants to the auricular flagging seen in the saltatrixoides-group of Oreotragus.


Everyone knows that the fur of klipspringers is oddly stiff and brittle, but how many realise that the colour of the hairs is restricted to the tips?

The following individual of subspecies schillingsi, in the Serengeti, was photographed consecutively as it walked among plant stems too flimsy to be visible but stiff enough to ruffle the fur in passing: and

When klipspringers have had a 'close shave' with a predator, and the brittle fur has been partly sheared in the scramble to escape, this is how it looks: and


In antilopin bovids of similar body size to klipspringers, such as the steenbok ( and oribis (, the juvenile suckles by splaying the fore legs. By contrast, in klipspringers a kneeling position seems to be adopted:

Posted on October 05, 2021 00:28 by milewski milewski | 10 comments | Leave a comment

October 01, 2021

The bambis, part 4: a new species of klipspringer in southern Africa?

In previous Posts, I have pointed out that naturalists in southern Africa have overlooked certain wild species or subspecies of large mammal, indigenous to the subcontinent. The first was the western wildebeest (Connochaetes taurinus mattosi) and the second was the Cape warthog (Phacochoerus aethiopicus aethiopicus).

Here is a third case, which happens to be a bambi.

Unlike the case of the warthog, extinction does not explain any low profile. On the contrary, this species remains as common as it was when Europeans first set foot on the subcontinent - and its profile is literally high.

Whereas the desert warthog might not be particularly photogenic, this time the overlooked species goes beyond photogenic because of its picturesque surroundings ( and and and and and and and many others shown in the fourth comment below).

Although klipspringers are unusually attractive at a distance, the crucial observation is close-up ( What nobody seems previously to have noticed is the variation in the form and colouration of the ear pinnae.

Is the dichotomy explained below not sufficient basis for different species, rather than just subspecies?

One reason why taxonomists have overlooked the diagnostic value of the ear pinnae is that this part of museum specimens tends to be distorted in the tanned skins. It is only when one examines photos that the true variation becomes clear. And, as I explained in several Posts about the western wildebeest (July 13, 14, 17 and 22), even experts can miss the obvious in the absence of a search-image.

As in the case of the western wildebeest, I discussed klipspringers at length several years ago with the late Colin Groves (see pages 287-292 in, and he acknowledged that he had simply never noticed this dichotomy in the ear pinnae among klipspringers.

Northern/eastern klipspringers comprise many subspecies ranging from Ethiopia southwards to northwestern Namibia in the west and Zululand in the east ( Although these vary in certain ways (e.g. females have horns in East African subspecies), their ear pinnae have a consistent appearance, as follows.

The front-of-ear looks angular ( and and and its anterior surface is furry (extremely so in these juveniles and and marked relatively boldly in dark and pale ( and and and and and and and and and

The colouration of the ear pinnae remains conspicuous even when they are turned partly backwards ( and and, plus many other photos in the first comment below).

By contrast, in klipspringers from the western parts of South Africa, plus southern and central Namibia, the front-of-ear is oblong ( and and and short-furred, with camouflage-colouration ( and and and

The ranges of these two basic types of klipspringer are largely disjunct within South Africa ( However, they meet in northwestern Namibia, where the subspecies (tyleri) is phenotypically similar to the eastern type despite occurring far to the west ( and and

In Damaraland (, the ear pinna seems intermediate:

Even if intergradation in Damaraland shows that the two species have not achieved reproductive isolation, the overall pattern dispels any notion that the oblong, inconspicuous ear pinna of the southwestern type (i.e. Cape klipspringer) is just an arid/semi-arid ecotype. This is because the southwestern type extends into a rainy climate in Western Cape province, while the northern/eastern type extends into a semi-arid climate in both northwestern Namibia and the Horn of Africa (e.g. see subspecies somalicus, where the ear pinnae remain true to form regardless of climate.

Although Groves and Grubb (2011) boldly elevated many subspecies of klipspringers to species-level, they completely overlooked the basic dichotomy in the ear pinnae. So, even if one keeps most klipspringers as mere subspecies, there is still reason to distinguish the Cape klipspringer as a species in its own right.

In terms of adaptive colouration: whereas the southwestern type of klipspringer (i.e. the Cape klipspringer) is thoroughly inconspicuous, the northern/eastern type has a front-of-ear arguably conspicuous enough to qualify as an auricular flag.

The following show evidence for an auricular flag in various subspecies of the northern/eastern type:

Ethiopia scroll down to two photos in
Central Kenya
Central Kenya
Eastern Kenya
Eastern Kenya
Eastern Kenya
Malawi/eastern Zambia
Malawi/eastern Zambia
South Africa several photos in
South Africa
South Africa
South Africa
South Africa
South Africa
South Africa
Locations unknown

The following show the lack of any auricular flag in the Cape klipspringer (i.e. the southwestern type):
Scroll one forward in

Posted on October 01, 2021 06:51 by milewski milewski | 9 comments | Leave a comment

October 04, 2021

Correcting the misidentification of klipspringer subspecies tyleri in iNaturalist

@alanhorstmann @jeremygilmore @colin25 @michalsloviak @chewitt1 @jwidness @alexdreyer @tonyrebelo @henrydelange @johnnybirder @kevinatbrakputs @calebcam @jakob

It has become habitual, in certain circles in southern Africa, to call the klipspringer of southern and central Namibia by the subspecies name tyleri, and the common name 'Namibian klipspringer'.

This habit has arisen in error and is contrary to the literature. It can therefore be corrected without any new peer-reviewed publication appearing.

The name tyleri was originally published on the basis of a specimen from near Benguela, and the common name is Angolan klipspringer. Therefore, any application of the name to Namibia should be in line with the features described in tyleri in the first place. Please note that the original location is not only in Angola, but deep in that country: 400 km from Namibia.

Groves and Grubb (2011,, revising all subspecies of klipspringers by examining the museum specimens, described tyleri and its distribution as follows on page 288: "underparts conspicuously, broadly, uniformly white...Females larger than the males...The Kaokoveld and S Angola".

Whiteness on the underparts, and females being larger-bodied than males, are both typical for klipspringers of eastern Africa (e.g. and and and and

The presence of white on the underparts persists to some extent in subspecies transvaalensis in eastern South Africa (e.g. and and and and

This is in contrast to the Cape klipspringer, in which the underparts are not white ( and and and and females are not larger-bodied than males.

The Kaokoveld ( includes only a small part of Namibia, in the extreme northwest of the country.

Based on the literature, then, the following is completely incorrect for Namibia: What is particularly incorrect is that the distribution of subspecies tyleri has slid all the way down to southern Namibia - where all photographs instead consistently show the Cape klipspringer (

This is how I think the misunderstanding has arisen.

Subspecies tyleri is Angolan but does extend some way into Namibia.

Klipspringers are widespread in Namibia but there have been no museum specimens collected from most of this country. Hence there has been assumption/extrapolation, and a gap in actual documentation has been filled in by pulling tyleri southwards.

This mistake has been inadvertently favourable to the hunting industry because it makes it look like the klipspringers on offer for trophies over much of Namibia are something other than just the Cape klipspringer. This unscientific bias has unwittingly crept beyond the hunting world, into iNaturalist.

In order to correct this problem, and to determine just how far south tyleri really extends, identifiers in iNaturalist should not nominate tyleri in Namibia unless the minimum requirement is met that the photo shows white underparts. And if any locations other than the extreme northwest of the country are involved, iNaturalists please be aware that you are claiming range-extensions which would ultimately have to be verified by specimens/publications in order to be scientific.

The onus falls on anyone identifying tyleri in iNaturalist to make the appropriate justification - which in the case of photos means at least for the underparts to be noticeably paler than in the Cape klipspringer.

To refresh your search-image for the real tyleri, please see This is so similar in colouration to some individuals of the subspecies in the Serengeti (schillingsi, that, were it not for the fact that females of the latter subspecies often grow horns, one might not be able to tell them apart.

Posted on October 04, 2021 21:50 by milewski milewski | 10 comments | Leave a comment

October 03, 2021

The bambis, part 5: possible new species-names for klipspringers in southern Africa

In my last Post I pointed out differences in the shape, pelage and colouration of the ear pinnae ( which suggest that the klipspringer currently called Oreotragus oreotragus oreotragus ( may deserve to be elevated in status from subspecies to species.

Another way in which O. o. oreotragus differs from other klipspringers, as previously pointed out by Groves and Grubb (2011), is in the direction of sexual dimorphism.

Most subspecies of klipspringers have females larger-bodied than males (e.g. transvaalensis and and and and and and and

However, in O. o. oreotragus it is males which are larger-bodied than females ( and and and and

Klipspringers have been investigated genetically ( There are indeed considerable genetic differences between the southwestern and northern/eastern klipspringers. On page 63, Le Roex (2008) states that "the level of differentiation between the S/SW and N/NE in particular is extremely high, it is comparable to some of the highest levels of intraspecific variation previously reported in bovids".

What this all means is that both the phenotypic and the genotypic evidence suggests that there are two, not one, species of klipspringers in southern Africa.

If so, what should we call them?

I am not a taxonomist, but this is my provisional understanding.

The first specimen formally named was in 1783, near Cape Town, by Zimmerman. The specific epithet was oreotragus.

As far as I know, the next specimen named was in 1853, in Ethiopia, by Temminck. The specific epithet was saltatrixoides.

Specimens from West and East Africa were named in 1899 (aceratos), 1902 (somalicus and schillingsi), 1911 (porteousi), and 1913 (aureus).

All names, besides the original oreotragus, applicable to southern Africa were relatively late: for example, transvaalensis 1917, tyleri in 1921, and stevensoni in 1946.

Although tyleri has come to be associated with Namibia, the first specimen was collected in Angola and tyleri actually occurs in only a limited part of Namibia.

Splitting klipspringers into two species would mean that the earliest name for the southwestern type is oreotragus (Zimmermann, 1783) and the earliest name for the northern/eastern type is saltatrixoides (Temminck, 1853).

Accordingly, the revised names in southern Africa would be as follows.

Oreotragus oreotragus would be the Cape klipspringer.

This occurs in Western Cape, Eastern Cape and Northern Cape provinces of South Africa, plus Namibia south of Damaraland. No subspecies have been named. However, there is noticeable variation from south (short) to north (long) in the length of the ear pinna (compare and with, which may be merely ecotypic or may possibly indicate a subspecies.

Oreotragus saltatrixoides would be the common klipspringer.

This occurs widely from Free State and Kwazulu-Natal provinces of South Africa to north of the equator. The subspecies in southern Africa are transvaalensis (southernmost, including southeastern Botswana and Lesotho), stevensoni (Zimbabwe and eastern Botswana), and tyleri (Angola plus northern Namibia).

The only zone of intergradation between these two species seems to be in Damaraland in north-central Namibia, where the phenotype seems intermediate between Oreotragus oreotragus and Oreotragus saltatrixoides tyleri (

The following photos illustrate each of these forms:

Oreotragus oreotragus and and and

Oreotragus saltatrixoides transvaalensis and and and

Oreotragus saltatrixoides stevensoni and and and

Oreotragus saltatrixoides tyleri and and and

Posted on October 03, 2021 02:39 by milewski milewski | 4 comments | Leave a comment

October 29, 2021

Why even the jaguar fears a mere anteater

The giant anteater ( and and its small relatives the tamanduas ( seem surprisingly nonchalant, for small-brained, toothless mammals with such slow metabolism that they cannot outdistance most predators.

This confidence may be based on a 'superpower' unique to the anteaters of central and South America.

The triceps ( is a major muscle on the upper fore limb which straightens the limb (think of pushups). It is particularly well-developed in the Myrmecophagidae. These anteaters find food by scratching into hard surfaces with their fore limbs, which are twice as muscular as their hind limbs.

However, the giant anteater and tamanduas are unusual among mammals in that the triceps is attached not only in the usual way to the ulna, but also by means of an extended tendon to the main claw-bearing digits ( and and and and and

The apparent result is that:

  • the muscular power whereby these animals squeeze-impale attackers with their claws is that of not only the 'forearm' but also the 'upper arm', and
  • maximum force can be applied by the claws while the fore limb is stretched out, keeping the opponent safely at arm's length.

The unusual development of this flexion mechanism (which facilitates both breaking into termitaria/wood and talon-like stabbing) helps to explain why the giant anteater can sometimes stare down even the jaguar (Panthera onca), and why tamanduas choose to stand confidently with fore legs spread when approached.

Effectively the giant anteater has substitutes for canine teeth, longer than the teeth of the jaguar, and these are powered by muscles and tendons superior to the jaw muscles of the jaguar.

It is this largely unapparent weaponry that seems to be the basis for the warning colouration on the forequarters, and most distinctly on the fore foot of the giant anteater.

The aposematic pattern of the giant anteater includes a dark bar on the pale fore feet, as if to draw particular attention to the hazard hidden there ( and and and and

In tamanduas, the dark band on the otherwise pale shoulders does not emphasise the fore limbs particularly (see video in However, the defensive posture displays the claws and the brawniness of the fore limbs ( and

When juveniles ride the mothers, the banding on the shoulders is reinforced rather than disrupted, suggesting self-advertisement rather than camouflage.


These anteaters differ from unambivalently aposematic mammals such as skunks because their conspicuous features of colouration remain partial/subtle enough to allow the animals to blend in when stationary. In the case of the giant anteater, the plain-coloured tail balances the functions of the bold markings. It can alternately cover and disguise the sleeping body, or expand in profile to exaggerate the body size of the animal in defensive display.

In the case of tamanduas the conspicuous pattern is absent in many individuals in a complex system which includes plain, all-pale and all-dark colour-morphs within a given population, plus geographic variation among populations.

However, warning colouration is well-developed enough, overall, in these anteaters to give pause to relatively big-brained carnivores such as felids and canids. In tamanduas the aposematism may be based largely on the noxious secretions of the anal glands, but in the giant anteater it is surely based on claws, the power of which is not self-evident.

Posted on October 29, 2021 11:56 by milewski milewski | 6 comments | Leave a comment

October 10, 2021

Diet of the feral camel in Australia, part 2

The most recent wild ancestor of the dromedary (Camelus dromedarius) lived in what is now Dubai ( and on a remote coastal plain which is hard to relate to the directions of the compass but forms a 'horn' of the Arabian subcontinent in the same way that the Horn of Africa relates to the African continent.

Given this origin, it might be informative to refer the favourite food-plants of the dromedary, in its feral state, in Australia to the flora of Arabia. In particular, which of the genera preferred in Australia are also indigenous to Arabia, albeit as different species?

A principle to bear in mind is that, in general, the leaves and shoots of stem-spinescent or hedge-forming plants are more palatable and nutritious than those of plants lacking these structural defences. Leaf-spinescent plants (other than thistles,,and%20camels%20are%20the%20answer. and tend to follow the opposite trend. Their foliage tends to be nutrient-poor, epitomised by the distinctively Australian hummock grasses (Triodia, see

In comparing Australia with Arabia, we can start with the amaranths and other halophytes (

Atriplex, a cosmopolitan genus of sodic-adapted shrubs and herbaceous plants, is locally conspicuous in semi-arid Australia (,staple%20diet%20of%20many%20animals.), and inconspicuous in Arabia (

Wherever it occurs, Atriplex is a fairly nutritious plant for herbivores ( and However, its food-value tends to be limited because its concentraction of sodium is not necessarily matched by other useful elements.

Probably more important in the diet of the dromedary in Arabia is the related genus Caroxylon, which does not occur in Australia and is associated with nutrient-rich soils rather than merely sodic ones. The branching stems and diminutive leaves (e.g. see and provide antiherbivore defences lacking in Atriplex and most of the other amaranths in Australia. This suggests that Caroxylon is more palatable than Atriplex to the dromedary.

One way to view the various halophytic amaranths (Atriplex, Chenopodium, Enchylaena, Maireana, Sclerolaena, Tecticornia) eaten by the feral dromedary in Australia is as nutrient-poor counterparts - which were relatively exempt from herbivory in Australia before the arrival of domestic livestock - to Caroxylon.

The amaranth Ptilotus ( is non-halophytic but conforms to this pattern in being common but not nutritious enough to be under pressure from herbivores. This is true notwithstanding the phosphorus-richness of certain species of Ptilotus (

Zygophyllaceae are unrelated to amaranths phylogenetically, but show a similar relationship to sodicity and herbivory. Although Zygophyllum occurs in Arabia and in Australia, the closely related genus Tetraena - absent from Australia - has a growth-form convergent with Caroxylon in its adaptation for intense herbivory ( and

The zygophylls also contain Tribulus, which is not halophytic. This is a favourite food of the dromedary ( and indigenous to both Australia and Arabia, although the commonest species has probably been introduced anthropogenically (

Portulaca is yet another genus indigenous to both Australia and Arabia, and likely to be a favourite food-plant of the dromedary in both regions.

Acacias occur in both Australia and Arabia, but in the form of different genera. Whereas the species eaten by the feral dromedary in Australia belong to the genus Acacia and have phyllodes instead of leaves, those likely to have been eaten in Arabia belong to the genus Vachellia, have bipinnately compound leaves, and are extremely spinescent ( and

Carissa and Capparis nowhere dominate the vegetation, but exemplify preferred species shared between Australia and Arabia. Not only is the dromedary likely to eat these plants (which are variably spinescent depending on pressure from herbivory) in both regions, but the same species is indigenous in both cases ( and

The feral dromedary in Australia coexists in places with kangaroos. However, there is little competition for food, for several reasons.

Firstly, all species of kangaroos prefer grasses, which are generally not preferred by the feral dromedary. Secondly, kangaroos do not generally eat acacias, eucalypts or eremophilas. Thirdly, the dromedary can reach twice - and perhaps threefold ( - as high as kangaroos can. And fourthly, much of the range of the feral dromedary is in the Australian Empty Quarter, where all kangaroos were scarce at the time of European arrival and remain scarce today.

It is noteworthy that the feral camel accepts eucalypts and proteas to a greater extent than hummock grasses.

I can summarise as follows.

Although the vegetation differs greatly between semi-arid Australia and Arabia, the dromedary is mobile and versatile enough to find equivalent, and in many cases closely related, plants to eat in both regions. Among comparable genera of favourite food plants, Australian species tend to be less spinescent or hedged than Arabian species, which may allow the dromedary to forage more efficiently - but not necessarily more sustainably - in its adopted than in its original habitat.

Posted on October 10, 2021 22:44 by milewski milewski | 9 comments | Leave a comment

Diet of the feral camel in Australia, part 1

Camelus dromedarius ( is unusual among the feral animals in Australia.

Firstly, among all the domestic species of mammals, the dromedary is least closely associated with any known wild ancestor - despite domestication having occurred as recently as four thousand years ago.

Secondly, this is the only feral ungulate successful in the extensive nutrient-desert that I have called the Australian Empty Quarter (see my last Post and

Thirdly, the dromedary has such slow metabolism, growth and reproduction, relative to most other artiodactyls, that it seems somewhat convergent with extinct large marsupials (e.g. of the Pleistocene in Australia (none of which is known to have occurred in the Australian Empty Quarter).

Given how odd the dromedary is for a domestic herbivore - resembling a wild animal 'pre-adapted' for the Australian semi-arid zone - its diet in its adopted habitat ( and and is of obvious interest.

What can we say about the ecological nature of those genera and species of plants most preferred by the dromedary in its feral state in Australia?

The overall finding is hardly surprising. The preferred plants tend to belong to:

  • cosmopolitan genera and weedy species
  • nutritional categories which boost palatability (e.g. nutrient-parasitism and symbiotic nitrogen-fixation)
  • genera and species restricted to the patches of relatively nutrient-rich soils (by Australian standards), and
  • regeneration after wildfires.

The plant species preferred by the dromedary in Australia are generally not the dominant/commonest ones, and this is particularly so in the Australian Empty Quarter. Instead, they tend to belong to families such as the Amaranthaceae, possessing soft foliage and growing on the least acidic soils or as temporary flushes dependent on ash.

Favourite food-plants of the feral dromedary, in the category of symbiotic nitrogen-fixers, belong to the Mimosaceae and Fabaceae.

In the former family are Acacia oswaldii ( and and several other species in the same genus, some of which are spinescent ( and

In the latter family are Erythrina (, Crotalaria, Indigofera, Rhynchosia, and Swainsona (

Favourite food-plants in the category of parasites (including both mistletoes and free-standing shrubs which parasitise the roots of other plants) are Amyema, Anthobolus, Cassytha, Cuscuta, Lysiana ( and Santalum spp. (

Other favourite food-plants tend to belong to genera occurring naturally on several continents, some of which can be called cosmopolitan.

These are (in alphabetical order):

Kali (

The following genera are restricted to Australia but associated with sodic soils: Enchylaena, Lawrencia, Maireana, Sclerolaena and Tecticornia.

This brings us to what are perhaps the most interesting of the favourite food-plants, i.e. those belonging to typically Australian families/genera.

These are (in no particular order) as follows:

Eucalyptus gammophylla (
Grevillea juncifolia ( and G. eriostachya (
Codonocarpus cotinifolius (
Eremophila longifolia ( and
Brachychiton gregorii (
Lechenaultia divaricata (
Ptilotus spp. ( and
Calotis hispidula (
Rhodanthe floribunda (
Scaevola parvifolia (
Stylobasium spathulatum (

Atalaya hemiglauca ( belongs to a mainly Australian genus with one species in southern Africa.

What does the vegetation look like when/where the favourite food-plants of the feral dromedary are so common that they dominate the scene? Here are some glimpses.

Regeneration after wildfire:

Prominence of phyllodinous acacias:

Prominence of 'saltbush' and other amaranths adapted to sodic soils:

to be continued...

Posted on October 10, 2021 08:45 by milewski milewski | 3 comments | Leave a comment

October 08, 2021

The bambis, part 7: why do certain genera show tropical hues?

Tropical organisms often seem more colourful than organisms from the non-tropical latitudes ( Think of coral reefs and Amazonian parrots.

We would not expect this trend to apply to ungulates, because neither the hoofed mammals nor the carnivores which hunt them can see hues such as red and green. For these animals, even browns may be effectively just shades of grey.

In the visual systems of ungulates and carnivores, the main sensitivity is to movement, not colour. And hues would be indiscernible at night anyway - even to the most light-sensitive eyes of nocturnal animals.

So it is puzzling that two types of small antelopes in Africa seem more colourful in the tropical than in the non-tropical parts of their ranges, and that the patterns are convergent.

Bush duikers (Sylvicapra, and klipspringers (Oreotragus, are not particularly closely related to each other, but both range widely across sub-Saharan Africa. In both cases the fur is uniformly brownish at high latitudes in southern Africa, but differentiated into yellowish/reddish hues vs greyish in the tropics.

And in both cases the richer hues occur on the forequarters, whereas the greyish occurs on the hindquarters.



Not only have Sylvicapra and Oreotragus converged with each other in this differentiation, but both have converged somewhat with a third, unrelated genus, namely Madoqua, which is restricted to the tropics.


The hues seen in these antelopes are dull compared with other tropical organisms, but raise a puzzle nonetheless.

In all three genera, the overall colouration is adaptively inconspicuous, allowing the figures to blend into their environments.

In which ways does differentiation of reddish at the anterior of the figure vs greyish at the posterior of the figure help to disguise small antelopes - particularly in the bright light of the tropics?

One possibility is that certain birds - which see all the hues - are important predators for bambis.

I refer in particular to the martial eagle (Polemaetus bellicosus,

See and and and and and and and and and and and and and

Posted on October 08, 2021 10:12 by milewski milewski | 1 comment | Leave a comment

October 09, 2021

The Australian Empty Quarter: epitome of a nutrient-desert

Everyone knows that Australia is the driest continent. However, how many know that 'desert' in Australia refers less to a lack of water than to a lack of nutrients?

On most maps of land use in Australia, a large-scale pattern is obvious but does not seem to have been pointed out as such. This is a broad vertical band across the western half of the continent, centred just west of the border between Western Australia ( and South Australia/Northern Territory. The climate varies from tropical in the north to temperate in the south.

In this broad band there is, to this day, negligible farming or other utilisation of the land (see and and and and and and and

This feature needs a name, and I suggest we call it the Australian Empty Quarter.

What is most surprising about the Australian Empty Quarter is how densely-vegetated it is with evergreen perennial plants ( and and and and and and

The driest part of Australia, which has sparse vegetation, occurs far to the east and is a different geographical feature ( and

The Australian Empty Quarter, despite looking far more luxuriant than the conventional image of desert, is even poorer in large animals than the rest of the continent. The emu (Dromaius novaehollandiae, and and kangaroos (mainly Osphranter rufus, and and are largely absent.

Various other species of animals show a similar gap in their distributions ( and

The most significant plants in the Australian Empty Quarter are hummock grasses belonging to the genus Triodia ( These are adapted to nutrient-poverty and fire to the degree that they have minimal value for herbivores ( Their leaves are woody, resinous and unpalatable.

The ultimate environmental reason for the Australian Empty Quarter is a combination of extreme flatness and underlying bedrock of nutrient-poor sediments such as sandstone. This land has been geologically stable since the time of dinosaurs, so that the soils, sandy and poor to start with, have become profoundly depleted of phosphorus and zinc in particular.

This limits herbivory so much that vegetation is left to grow until wildfire returns, and combustion has replaced digestion as the most important recycler of nutrients.

The Australian Empty Quarter is best understood as a nutrient-desert rather than a rainfall-desert because, even if it were well-watered, it would remain largely devoid of large animals. Although this zone is semi-arid, it is ecologically aligned with the African Empty Quarter (see my Post of July 18, 2021) rather than the conventional concept of a desert.

As an example of a nutrient-desert, the Australian Empty Quarter is far more extreme than the Kalahari-derived sand-sheet, covered with miombo woodland (, in Angola - in which the incidence of large animals is minimal by African standards but categorically greater than in any part of Australia.

One of the principles illustrated is this:

There are some climates just too dry for the vegetation to maintain cover over the land, and this is the conventional concept of desert. However, no soils on this Earth are so nutrient-poor that woody plants cannot grow on them, albeit slowly. Thus arises the combination we see in the Australian Empty Quarter: a vegetated plain effectively useless to man and beast.

Except, that is, for a camel...

Posted on October 09, 2021 06:08 by milewski milewski | 4 comments | Leave a comment

October 13, 2021

Bird-beak hakea epitomises plants dedicated to combustion

Bird-beak hakea (Hakea orthorrhyncha, and and and has the 'perfect resume' as an example of adaptation to an ecological syndrome which is seen at its most extreme in Western Australia.

It is one of those plants that 'says it all' in its combination of the various adaptive features of organisms to a particular regime in the natural environment.

Australia - and particularly Western Australia - has the poorest soils in the world: extensive deep sands exhausted of most nutrients by eons of weathering and leaching on a flat landscape.

On such soils, plants are not worth eating, which means that they tend to be consumed and recycled by combustion instead of digestion.

Plants well-suited to such environments, with their periodic wildfires, include multi-stemmed shrubs. They have foliage which is flammable even when green, and the means to regenerate new foliage rapidly from the ashes.

In the case of bird-beak hakea this means a woody burl just below ground-level, which survives even if all the stems of the plant are killed by the heat. This lignotuber ( produces new shoots without having to start again from seed.

And a crucial point to understand about plants is that - if appropriately adapted and living in sunny climates - they can make plenty of carbohydrate even on poor soils. This is partly because the enzymes of photosynthesis depend on metals, particularly magnesium and iron, which remain sufficient even where the core nutrients (particularly phosphorus and zinc) have become vanishingly scarce.

Carbohydrate is what sugar, plant fibre and wood are made of, depending on the degree of polymerisation. Because carbohydrate is the one product that nutrient-poor plants are affluent in, they use it in various ways to offset all the other disadvantages in their environments.

This is why bird-beak hakea has recruited birds to transport its pollen. Instead of settling for bees, it has the nectar to attract far larger, more energetic pollinators. Red is a hue invisible to bees but conspicuous to birds (!lightbox-uid-0), and it signifies a font of sugar as well as hinting at the flames that propagate the plant in the longer term.

So bird-beak hakea is both 'pyrophilic' (loving fire) and 'ornithophilic' (loving honeyaters and other pollinating birds).

Bird-beak hakea uses its carbohydrates to fortify its leaves with lignin, making them stiff, spinescent and nearly as flammable as cardboard. And it also converts its roots into a dense, cardboard-like mat, protected from fire by being just below the sand (see This mat absorbs, before they are lost, any nutrients that land in the form of dust and ash, thus providing the means for regrowth.

Furthermore, this species uses its carbohydrates in a remarkable way to protect its seeds. The seed-capsule is fortified into a lump of wood, 2 cm by 4 cm, which remains sealed and alive for years until the next fire arrives.

This makes bird-beak hakea both 'bradysporous' (storing the seed on the plant instead of in the ground, and woody-fruited (protecting the seed from parrots and other seed-eating animals).

Various flammable plants on other continents show one or two of the above features, but none beyond Australia combines them all in one species. This is largely because nutrient-poverty is not as extensive and extreme, and wildfire does not replace herbivory as thoroughly, on other continents.

For example, in the Mediterranean Basin there are several types of shrub which possess lignotubers ( and and Others have evergreen, spinescent leaves ( But none of these plants is ornithophilous or bradysporous, and all lack cluster roots.

In South Africa there are proteas, belonging to the same family as bird-beak hakea, that have lignotubers, cluster roots, bird-pollinated flowers, and even bradyspory (e.g. But they lack leaf-spinescence and woody fruits.

In North America there are 'closed-cone pines (see and with what amount to woody fruits. However, these lack all the other features of the syndrome, including a shrubby growth-form.

Plants such as bird-beak hakea ( and and and and and and nowhere dominate the vegetation, even on the coastal sandplains of southwestern Australia (

But the fact that any such species exists is testimony to the ecological peculiarity of Australia among the continents. In its own way, bird-beak hakea is as odd, by global standards, as the kangaroos which exert a minimal effect in its habitat (

Posted on October 13, 2021 20:36 by milewski milewski | 4 comments | Leave a comment