Archivos de diario de octubre 2021

01 de octubre de 2021

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


...continued from

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

to be continued in

Publicado el octubre 1, 2021 06:51 MAÑANA por milewski milewski | 9 comentarios | Deja un comentario

03 de octubre de 2021

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

...continued from

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

to be continued in

Publicado el octubre 3, 2021 02:39 MAÑANA por milewski milewski | 4 comentarios | Deja un comentario

04 de octubre de 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.

Publicado el octubre 4, 2021 09:50 TARDE por milewski milewski | 10 comentarios | Deja un comentario

05 de octubre de 2021

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

...continued from

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:

to be continued in

Publicado el octubre 5, 2021 12:28 MAÑANA por milewski milewski | 10 comentarios | Deja un comentario

08 de octubre de 2021

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

@tonyrebelo @jeremygilmore @botswanabugs @paradoxornithidae @matthewinabinett @capracornelius @tandala

...continued from

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 that 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 mammals.

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

My hypothesis is that the patchwork of hues shown above acts as an element of disruptive colouration, reducing the conspicuousness of bambis to eagles.

to be continued in

Publicado el octubre 8, 2021 10:12 MAÑANA por milewski milewski | 3 comentarios | Deja un comentario

09 de octubre de 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 certain large-scale pattern is obvious. However, it does not seem to have been pointed out as a distinctive geographical feature of Australia.

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 longitudinal 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 truly does has sparse vegetation, occurs far to the east. It constitutes a different geographical feature, viz.

The Australian Empty Quarter, despite looking far more luxuriant than the conventional image of desert, is poor habitat for the largest-bodied Australian animals.

This is illustrated by the scarcity/absence of

Various other familiar species of animals show a similar gap in their distributions, e.g.

(It is noteworthy that feral populations of the dromedary, Camelus dromedarius, have fared well in the Australian Empty Quarter,

The converse pattern applies to certain slow-metabolising forms, e.g.

The most significant plants in the Australian Empty Quarter are hummock grasses belonging to the genus Triodia ( These are adapted so extremely to nutrient-poverty and fire 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. Thus, the soils - sandy and poor to start with - have become monotonously depleted of phosphorus and zinc in particular.

This poverty limits herbivory so much that vegetation is left to grow until wildfire returns (,that%20are%20less%20fire%2Dadapted.). 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 (, 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 the latter, the incidence of large animals is minimal by African standards, but categorically greater than in any part of Australia.

One of the principles illustrated by these 'Empty Quarters' is as follows:

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 (indigenous) beast.

Publicado el octubre 9, 2021 06:08 MAÑANA por milewski milewski | 4 comentarios | Deja un comentario

10 de octubre de 2021

Diet of the feral dromedary (Camelus dromedarius) 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 in

Publicado el octubre 10, 2021 08:45 MAÑANA por milewski milewski | 4 comentarios | Deja un comentario

Diet of the feral dromedary (Camelus dromedarius) in Australia, part 2

....continued from

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.

Publicado el octubre 10, 2021 10:44 TARDE por milewski milewski | 9 comentarios | Deja un comentario

13 de octubre de 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 (

Publicado el octubre 13, 2021 08:36 TARDE por milewski milewski | 4 comentarios | Deja un comentario

14 de octubre de 2021

Why Eucalyptus erythrocorys tends to self-amputate in cultivation

Eucalyptus erythrocorys ( and and and and has large blooms: bright yellow and with exotic-looking red opercula (

This makes for a cheerful - even spectacular - appearance as summer becomes autumn in the mediterranean-type climate.

So it is unsurprising that this species has become a horticultural favourite as a large shrub or small tree ( It is planted in gardens and along streets in Australia (particularly in the west) and in the similar climate of southern California.

However, cultivating the species in this way ( and brings the practical disadvantage that the several boles of each individual plant tend to grow at angles, not upright.

As a result of this leaning tendency, top-heaviness often results in partial collapse. One of the boles suddenly breaks, felling that part of the crown and its growing foliage in what looks like spontaneous auto-amputation.

Now, everyone knows that various species of eucalypts, which grow naturally as large trees, have a disconcerting habit of suddenly dropping large branches ( and It is understandable that tall trees would benefit from getting rid of redundant lower branches and dead sticks, but what is noteworthy about eucalypts is that the branches are usually shed with the foliage still growing.

The fact that various species of eucalypts spontaneously - and dangerously - jettison branches in a state of apparent vitality has led to the term 'self-pruning' (

Seen in this context, the proneness of cultivated E. erythrocorys to partial collapse seems incongruous. This is because, on this relatively small plant, such a large proportion of the stem system is 'shed' that the action resembles not self-pruning as much as an unsuccessful attempt at suicide.

Curious about this apparently maladaptive behaviour, I visited the plant in its natural habitat near the coast south of Dongara in southwestern Western Australia ( and,_Western_Australia and Here E. erythrocorys is locally dominant on ridges of coastal limestone, with a heathy understorey (see photo no. 12 in

What I noticed immediately is that, in its natural state, E. erythrocorys is more like a mallee ( than it appears to be in the suburbs or in photos singling out the more statuesque specimens in the wild (e.g. In nature, each individual usually has more than six stems emerging at ground-level even if the lignotuber, so typical of mallees, is not particularly well-developed.

This brought me to the realization that the growth-form encouraged in cultivation is different from the wild, multi-stemmed one. Gardeners, ignorant of the natural shape of the plant, understandably tend to cull the stems to a few which resemble boles of a (small) tree.

Closer examination distinguished E. erythrocorys from all the other species of mallees with which I am familiar in the wild. The stems, although initially growing upwards as expected, sprawl down to the become prostrate in their distal sections. The result is a growth-form similar to mallee but with much of the outer foliage trailing along the ground.

Why does E. erythrocorys differ from other multi-stemmed, wildfire-tolerant eucalypts in having this oddly recurved growth-form?

One possible reason is its tenuous relationship with fire in a type of vegetation which is not easily classified as either typical mallee ( or typical kwongan (

Most species of mallee are not only tolerant of wildfire, but intimately adapted to a regime of periodic combustion in which all their stems die by scorching, and growth resumes from ground level. Usually the vegetation is dense enough that the flames engulf all including the crowns of the mallees. However, eucalypts tend to exclude flammable shrubs from the patch directly under the crown, which means that, if the stand is sparse, there is a chance that the fire will fail to ignite the foliage of the upper storey, simply burning through the heathy understorey and leaving the eucalypts partly unburnt.

In the case of E. erythrocorys, the vegetation is indeed relatively sparse, partly because the surface is so stony. The heathy understorey looks barely dense enough to carry the flames across the empty patches under the mallees.

What E. erythrocorys seems to arrange, by having its outermost foliage trailing back down to the ground, is a ladder whereby the flames can climb up into the crown. This would ensure the desired combustion of the foliage, which as in other mallees rejuvenates the plant and self-fertilises it with its own ash.

The problem in cultivation is that no gardener or arborist, private or municipal, wants an untidy sprawl-mallee. So the natural shape of the plant is modified in the sapling. However, this cannot correct the leaning which is 'hardwired' in the remaining few boles. This inclination of the foliage towards the ground, now made dysfunctional, results sooner or later in partial collapse.

In summary, my finding is that the auto-amputation of the stem-system of E. erythrocorys is not a case of the sort of self-pruning so well-known in tree eucalypts. Instead it is a result of artificial distortion of the natural shape of the plant.

Horticulturally desirable though this species is, its natural adaptations are such that growing it as a tree is unlikely to be achieved without selective breeding.

Publicado el octubre 14, 2021 10:25 TARDE por milewski milewski | 3 comentarios | Deja un comentario