Diet of the sable antelope, part 2: Hippotragus niger niger, with particular reference to basaltic soils in Zambezi National Park

@troos @wynand_uys @richardgill @bartwursten @dejong @simontonge @tonyrebelo @jeremygilmore @jwidness @jakob @adriaan_grobler @reubenheydenrych @andrew_hankey

...continued from https://www.inaturalist.org/journal/milewski/87034-diet-of-the-sable-antelope-part-1-hippotragus-niger-roosevelti-with-special-mention-of-osteophagy#

My reference (xeroxed) is:
Richard D Estes and Runhild K Estes (1970) The sable in Rhodesia. Second progress report. National Geographic Society, hippotragine antelope study.

As in part 1, my reason for making this electronic record is that the valuable information in this report, now more than half a century old, risks permanent loss otherwise.

More particularly, the main location, in what is now Zambezi National Park (https://en.wikipedia.org/wiki/Zambezi_National_Park), seems never to have been subsequently visited by naturalists. It happens inadvertently to be shown in https://www.inaturalist.org/observations/191489840, which is not an actual plotting of the observation.

Estes' main study area, 26 km upriver from Victoria Falls, now approximates merely to a remote picnic site. I refer to Chamunzi, as shown in https://www.4x4community.co.za/forum/attachment.php?attachmentid=387193&d=1453821503.

I assume that this obsolescence is because the original Victoria Falls National Park was reconfigured with the gazetting of the adjacent Zambezi National Park in 1979 (a decade after the fieldwork reported here). The 'Chundu Loop' (https://geographic.org/geographic_names/name.php?uni=-3187334&fid=6791&c=zimbabwe and https://geoyp.com/17/chundu-loop-2136431/ and https://mapcarta.com/14131676) around Chundu Vlei, consisting of tracks routinely accessible to visitors to Victoria Falls National Park in 1969, seem to have been excised from the tourist circuit in Zambezi National Park. This permanently closed the area to the public, except for 4X4 adventurers.

The fact that Estes' report refers to a now-forgotten patch of basaltic terrain makes the information all the more worthy of securing in the public record.

Fieldwork was conducted in June-July 1969.

Description of relevant vegetation on basaltic soils northwest of Chundu Vlei in what was, at the time, Victoria Falls National Park (page 4):

(as in part 1, I have brought all the scientific names up to date)

EXCERPTS

"The grasses...are mostly small and sparse annuals, that turn almost white in the dry season. Aristida spp. predominate in many places. On heavy clay soils, a low annual, Moorochloa eruciformis, tended to be dominant, while Andropogon fastigiatus was often common on rocky ground. Taller, tufted perennials occurring in scattered clumps, especially along dry watercourses and on hillsides, included Andropogon gayanus mainly, followed by Cymbopogon caesius, and Hyparrhenia spp., with occasional Sorghum versicolor and Bothriochloa pertusa [sic]. The seasonally waterlogged vlei grasslands are dominated by tufted perennials. The leaf table averaged about two feet high in June/July, with flowering stalks making a thin screen of up to 6 ft. On one meadow (Chundu Loop) that was sampled for dominant species, Ischaemum afrum and Andropogon gayanus appeared co-dominant, followed by Cymbopogon caesius, Hyparrhenia filipendula (?), Heteropogon contortus, Bothriochloa pertusa [sic], Dicanthium annulatum and tall Aristida spp., with Moorochloa eruciformis and Andropogon fastigiatus on the edge of the bordering mopane scrub. The vlei grasslands had a reddish brown colour, though green stool shoots were still being produced by some plants late in July, especially Cymbopogon caesius (Pepper grass)[https://pza.sanbi.org/cymbopogon-caesius]."

Description of relevant vegetation on deep siliceous sand in what was, at the time, Victoria Falls National Park (page 4):

"The grass cover here is better and richer in species than in the basalt zone, consisting mainly of tufted perennials...The leaf table averaged about one foot and all grasses and already ceased growing, apparently before the end of June...Chamabonda Vlei, a drainage line grassland some 12 miles long..., has a somewhat different species composition than vleis of the basalt soils. The grass cover tended to be thicker and taller, dominated by Hyparrhenia spp., with abundant Heteropogon contortus, Digitaria sp., and Eragrostis superba, with an understorey of Cynodon dactylon and Panicum repens, which formed a lush sward on the site of a dried-up pan."

The following shows Hippotragus niger niger in Chamabonda Vlei, which now falls within Zambezi National Park:

https://www.inaturalist.org/observations/45158270

The following shows a dried-up pan and dense grass in the same area:

https://www.inaturalist.org/observations/86521961

In the following dietary list, I have updated the species-names, several of which have been revised/synonymised, since 1969.

V = Victoria Falls National Park (now Zambezi National Park)
C = Chobe National Park
H = Hwange National Park (Robins Camp)
M = Matobos National Park

GRAMINOIDS

*Asterisked spp. are those heavily utilised by H. niger niger in this study

1 = good forage value, 2 = average forage value, 3 = poor forage value, x = occurring in disturbed areas (Rattray J M 1960 The habit, distribution, habitat, forage value and veld indicator value of the commoner Southern Rhodesian grasses. Rhod. Agr. J. 57(5): 424).

Poaceae:

*Andropogon gayanus 1 V H
https://www.inaturalist.org/taxa/208518-Andropogon-gayanus

Andropogon chinensis 2 V
https://www.inaturalist.org/observations?taxon_id=506830

*Andropogon fastigiatus 2 V
https://www.inaturalist.org/taxa/279544-Andropogon-fastigiatus

Andropogon schirensis 2 V
https://www.inaturalist.org/taxa/506838-Andropogon-schirensis

Aristida adscensionis H
https://www.inaturalist.org/taxa/75559-Aristida-adscensionis

Bothriochloa insculpta 1 H M
https://www.inaturalist.org/taxa/279566-Bothriochloa-insculpta

Chloris gayana 1 H
https://www.inaturalist.org/taxa/76292-Chloris-gayana

Chloris virgata 1 x H
https://www.inaturalist.org/taxa/62918-Chloris-virgata

Cynodon dactylon 1 x C
https://www.inaturalist.org/taxa/58371-Cynodon-dactylon

Dactyloctenium giganteum 1 C
https://www.inaturalist.org/taxa/583418-Dactyloctenium-giganteum

Dicanthium annulatum 2 H
https://en.wikipedia.org/wiki/Dichanthium_annulatum

*Digitaria eriantha (incl. setivalva) 1 C M
https://www.inaturalist.org/taxa/161903-Digitaria-eriantha

*Digitaria milanjiana 1 H
https://www.inaturalist.org/taxa/161911-Digitaria-milanjiana

Eragrostis rigidior 2 x C
https://www.inaturalist.org/taxa/584582-Eragrostis-rigidior

Eragrostis superba 2 V H
https://www.inaturalist.org/taxa/162412-Eragrostis-superba

*Heteropogon contortus 2 V H M
https://www.inaturalist.org/taxa/77394-Heteropogon-contortus

Hyparrhenia filipendula 2 H M
https://www.inaturalist.org/taxa/587635-Hyparrhenia-filipendula

*Ischaemum afrum V H
https://www.inaturalist.org/taxa/587952-Ischaemum-afrum

*Megathyrsus maximus 1 H M
https://www.inaturalist.org/taxa/1064938-Megathyrsus-maximus

*Moorochloa eruciformis 2 x V
https://www.inaturalist.org/taxa/969680-Moorochloa-eruciformis

Panicum coloratum 1 H
https://www.inaturalist.org/taxa/166075-Panicum-coloratum

Pogonarthria fleckii C
https://www.inaturalist.org/taxa/592295-Pogonarthria-fleckii

Pogonarthria squarrosa x M
https://www.inaturalist.org/taxa/461689-Pogonarthria-squarrosa

Rottboellia exaltata 1 x V
https://www.inaturalist.org/taxa/410498-Rottboellia-exaltata

Schizachyrium sanguineum 3 V
https://www.inaturalist.org/taxa/168601-Schizachyrium-sanguineum

Schmidtia pappophoroides 1 V C
https://www.inaturalist.org/taxa/336805-Schmidtia-pappophoroides

Setaria sphacelata 2 V
https://www.inaturalist.org/taxa/60312-Setaria-sphacelata

Sorghum versicolor 2 V
https://www.inaturalist.org/taxa/594607-Sorghum-versicolor

Sporobolus ioclados M
https://www.inaturalist.org/taxa/343100-Sporobolus-ioclados

Sporobolus panicoides 3 V

https://www.inaturalist.org/taxa/594679-Sporobolus-panicoides

*Themeda triandra 2 M
https://www.inaturalist.org/taxa/208571-Themeda-triandra

Urochloa brachyura 1 x C H
https://www.inaturalist.org/taxa/595884-Urochloa-brachyura

Urochloa brizantha 1 x H
https://www.inaturalist.org/taxa/279501-Urochloa-brizantha

Urochloa trichopus x H
https://www.inaturalist.org/taxa/595887-Urochloa-trichopus

HERBACEOUS DICOTYLEDONOUS PLANTS

Acanthaceae:

Blepharis bainesii V
https://www.inaturalist.org/taxa/581151-Blepharis-bainesii

WOODY PLANTS

Combretaceae:

Combretum apiculatum C
https://www.inaturalist.org/taxa/340059-Combretum-apiculatum

Euphorbiaceae:

Croton megalobotrys C
https://www.inaturalist.org/taxa/340314-Croton-megalobotrys

Apocynaceae:

Diplorhynchus condylocarpon V
https://www.inaturalist.org/taxa/340194-Diplorhynchus-condylocarpon

Tiliaceae:

Grewia monticola V
https://www.inaturalist.org/taxa/469315-Grewia-monticola

Asteraceae:

Tarchonanthus camphoratus M
https://www.inaturalist.org/taxa/474039-Tarchonanthus-camphoratus

Fabaceae: Faboideae:

Philenoptera nelsii C
https://www.inaturalist.org/taxa/546325-Philenoptera-nelsii

Philenoptera violacea V
https://www.inaturalist.org/taxa/340211-Philenoptera-violacea

Fabaceae: Caesalpinioideae:

Bauhinia petersiana V
https://www.inaturalist.org/taxa/68227-Bauhinia-petersiana

Malvaceae:
Thespesia garckeana V
https://www.inaturalist.org/taxa/1417064-Thespesia-garckeana

The following is another excerpt from the text in Estes and Estes (1970), relevant to diet.

EXCERPT

Pages 13-15:

"In general, dry grasses were selected [during the dry season, when observations were made], even when green shoots of species sable are known to eat at other times were present. Having previously noted that in other areas they invariably selected the tenderest and greenest grasses, the sight of sable subsisting on standing hay came as a surprise. It apparently marked a definite change-over in diet coinciding with the period when preferred grasses cease active growth. In fact, they continued to select many of the same species that we had seen sable feeding on in the rainy season...The fact that the shift took place while green shoots could still be found may indicate that the effort required to gain a fill of green grass outweighed its nutritional advantage over cured grass. In Victoria Falls National Park, the grazing preferences and behaviour of herds living in the mopane/mixed deciduous savanna [on basaltic soils] both differed considerably from the other sable we observed. Throughout June and July, the diet of the Big Herd [on basaltic soils], for instance, consisted largely of two small annuals: Moorochloa eruciformis and Andropogon fastigiatus. The former was particularly abundant in the mopane/Combretum scrub grassland where the herd spent most of its time. Such common constituents of vlei grasses as Andropogon schirensis and Andropogon gayanus, Sorghum versicolor, Cymbopogon caesius and Heteropogon contortus, present in scattered clumps, were grazed to a limited degree only, while Hyparrhenia spp., even though still producing green stool shoots in July, appeared untouched. The two annuals were not only completely dry but also lay on the ground as litter in many places. The Big Herd was harvesting the Moorochloa and A. fastigiatus like cattle feeding on loose hay. Each part of the pasture where the herd fed was worked over in minute detail. Often the sable spent several days in succession within an area of a few hundred square yards. Grazing animals progressed so slowly that a movement of no more than a few yards in half an hour was not exceptional. For example, a yearling was seen to stand without moving a single yard for 10 minutes, eating the whole time, gathering in large mouthfuls of the hay before pausing to chew and swallow. The heavy black cotton soils preferred by this Moorochloa crack deeply and become highly friable after drying and trampling. Consequently annuals were regularly pulled up by the roots, often with a clod of earth attached. The sable spent considerable time in discarding the clods, shaking their heads vigorously to break them off, gaping and pushing with their tongues to eject clods that got into their mouths. Roan and zebra feeding on the same type of pasture near the Salt Pan at Robins Camp were also seen to pull up many plants by the roots. By the time the herd had finished working over an area the ground was stripped bare in many places; in others unpalatable Aristida spp. concealed the extent of bare earth. Such a pattern of utilisation would create havoc in perennial grassland, but in a pasture consisting largely of annuals, it may be asserted that the sable were fully exploiting their food resources with a minimum of damage. Litter would have mulched and helped protect the soil against drying and excessive insolation. On the other hand, aside from fertilising the soil, the trampling of the sable made it more friable, helping to prevent 'capping' - a very common occurrence in Rhodesia due to understocking (Savory, pers. comm.) - which by preventing rain from penetrating the soil drastically reduces rainfall effectiveness. In any case, the real damage to such pasture in Victoria Falls National Park was done long ago...The same animals displayed another still more unusual feeding habit: they consumed quantities of a prostrate perennial herb, Blepharis bainesii, that resembled and was as prickly as a thistle. It grew abundantly in the same places as their favourite annual grasses, a small ball of spiny leaves surrounding blue flowers at the end of a thin, wiry stem. A sable would gingerly close its mouth over one, grip the stem with its lips, and pluck it. Then, standing with head outstretched and tilted to one side, mouth gaping, it would proceed to ensalivate the ball until it was soft enough to chew and swallow. Since it was impossible for us to pull up or hold one without pricking our fingers, sable apparently have pretty tough gums. Apart from the herds along the Zambezi, most of the other sable we observed followed what we had come to consider the normal grazing pattern for the species: they kept moving while grazing, from tuft to tuft of preferred perennial grasses, and usually shifted their ground from day to day. Andropogon gayanus, Ischaemum afrum, Heteropogon contortus, Digitaria eriantha, Bothriochloa pertusa [sic, https://www.inaturalist.org/taxa/159322-Bothriochloa-pertusa] and Dicanthium annulatum were heavily utilised in most areas. These are the same genera and many of the same species that sable prefer in Zambia, Tanzania and Angola; only Heteropogon contortus, commonly and unaffectionately known as spear grass because of its sharp, clinging seeds, is less common in regions of higher rainfall. Generally speaking, these and other preferred grasses were found growing most luxuriantly in the ecotone between woodland and vlei - i.e. on the 'edge'. The grasses commonly dominant in the lower and wetter parts of the vleis (Hyparrhenia spp., Tristachya superba, Setaria and other Digitaria spp.), taller and also greener, were largely unutilised in June and July. Perhaps in years when the vleis remained unburned, sable work their way toward the centre as the dry season advances and end up feeding on these other grasses. In Victoria Falls National Park, as already noted, a herd of bachelor males was more or less resident on the Chundu Loop vlei at the beginning of June (although feeding on the same grasses as sable that stayed on the edge). Not until July fifth was a nursey herd seen grazing out on this meadow. This and other observations suggested that sable do feed out in the vleis later in the dry season, with adult males in the vanguard. But in Wankie [Hwange] National Park and wherever roan occur together with sable, the former is seen feeding out in the middle of the vleis far more often than the latter. Their habitat and food preferences overlap, more or less, according to season and other factors, but the overlap occurs mainly on the edge, from which the two orient in opposite directions: sable toward the woodland and roan toward the grassland."

The following illustrate Blepharis bainesii:
https://www.inaturalist.org/observations/35404783
https://www.inaturalist.org/observations/116656787
https://www.inaturalist.org/observations/116656538
https://www.inaturalist.org/observations/111493238
https://www.inaturalist.org/observations/109524201
https://www.inaturalist.org/observations/109446512

to be continued in https://www.inaturalist.org/journal/milewski/87363-diet-of-the-sable-antelope-part-3-hippotragus-niger-variani-with-special-mention-of-geophagy#...

Publicado el 02 de diciembre de 2023 a las 06:59 AM por milewski