Diet of the sable antelope, part 1: Hippotragus niger roosevelti, with special mention of osteophagy

@paradoxornithidae @dejong @matthewinabinett @jakob @jwidness @simontonge @tandala @ldacosta

In the late 'sixties, the late Richard Estes (https://en.wikipedia.org/wiki/Richard_Despard_Estes) spent 10 weeks in the Shimba Hills in coastal Kenya. The dates were 17 Oct.-8 Dec. 1968 and 1-14 March 1969.

His purpose was to study a rare and threatened subspecies of large bovid, namely the eastern sable antelope (Hippotragus niger roosevelti, https://www.inaturalist.org/observations?taxon_id=698276).

Richard Estes was, at the time, an authority on the western white-bearded wildebeest (Connochaetes mearnsi), and he went on to become the global authority on the sable antelope.

The eastern sable antelope was originally restricted to a limited strip of coastal East Africa, straddling the border between Kenya and Tanzania.

Its habitat was the northernmost, attenuated form of miombo woodland (https://en.wikipedia.org/wiki/Miombo), in which only one species of Brachystegia persists under the equatorial regime of bimodal seasonal rainfall.

Estes undertook this study nearly 60 years ago. At that time, the eastern sable antelope still remained in small numbers on the coastal plain in Kenya, in attenuated woodland of Brachystegia spiciformis (https://www.inaturalist.org/taxa/340265-Brachystegia-spiciformis) and Afzelia quanzensis (https://www.inaturalist.org/taxa/340236-Afzelia-quanzensis), and at the edges of fire-free forest containing Manilkara and Diospyros. These populations at low altitudes, which Estes did not field-study, have since been exterminated.

The species has survived in Kenya only in the Shimba Hills. Here, the vegetation (https://www.inaturalist.org/journal/milewski/87074-flora-and-vegetation-of-shimba-hills-national-reserve-in-coastal-kenya-including-a-description-1969-by-richard-estes#) is a picturesque forest/savanna mosaic, only vaguely related to the northernmost miombo woodland.

The Shimba Hills were protected, before Estes' study, mainly for the purposes of watershed and forestry (with part of the area cleared for plantation of Pinus). The National Reserve was designated in 1968 (https://en.wikipedia.org/wiki/Shimba_Hills_National_Reserve and https://www.kws.go.ke/content/shimba-hills-national-reserve).

The main purpose of this Post is to record, electronically, previously unpublished information that risks being lost to Science with the passage of time.

In this, part 1, the topic is the diet of the eastern sable antelope in the Shimba Hills.

My reference (xeroxed) is:

*Richard D Estes and Runhild K Estes (1969) The Shimba Hills sable population. First progress report. National Geographic Society, hippotragine antelope study.

The above report includes data from:

+Table 15 in Glover P E (1969) Report on an ecological survey of the proposed Shimba Hills National Reserve. East African Wildlife Society. 148 pages (as referred to in the above report). This study was made in March through May 1968.

In the following dietary list (as well more generally as in all three parts of this series of Posts), I have updated the species-names, several of which have been revised/synonymised since 1969.

GRAMINOIDS

Cyperaceae:

*Cyperus hemisphaericus
https://www.inaturalist.org/taxa/939340-Cyperus-hemisphaericus

Poaceae:

*+Andropogon schirensis
https://www.inaturalist.org/taxa/506838-Andropogon-schirensis
eaten intensively in October and March

*+Ctenium concinnum
https://www.inaturalist.org/taxa/131655-Ctenium-concinnum

+Cymbopogon caesius
https://www.inaturalist.org/taxa/461690-Cymbopogon-caesius

*+Digitaria milanjiana
https://www.inaturalist.org/taxa/161911-Digitaria-milanjiana
eaten intensively in October and November

*+Diheteropogon amplectens
https://www.inaturalist.org/taxa/506862-Diheteropogon-amplectens

*Eragrostis perbella
https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:401411-1

+Eragrostis racemosa
https://www.inaturalist.org/taxa/584580-Eragrostis-racemosa

*Hylebates chlorochloe
https://plants.jstor.org/stable/10.5555/al.ap.flora.ftea008800

*+Hyparrhenia filipendula
https://www.inaturalist.org/taxa/587635-Hyparrhenia-filipendula
eaten intensively in October and November

*+Hyperthelia dissoluta
https://www.inaturalist.org/taxa/208799-Hyperthelia-dissoluta

+Megathyrsus infestus
https://www.inaturalist.org/observations/175707529

*+Megathyrsus maximus
https://www.inaturalist.org/taxa/1064938-Megathyrsus-maximus
eaten intensively in November and March

*+Panicum trichocladum
https://www.inaturalist.org/taxa/1154367-Panicum-trichocladum

*Paspalum orbiculare
https://www.inaturalist.org/taxa/404650-Paspalum-orbiculare

*Setaria parviflora
https://www.inaturalist.org/taxa/79068-Setaria-parviflora

*Setaria sphacelata
https://www.inaturalist.org/taxa/60312-Setaria-sphacelata
eaten intensively in March

*+Setaria trinervia (possibly synonymous with sphacelata)
https://plants.jstor.org/stable/10.5555/al.ap.flora.flota016251

+Sporobolus pyramidalis
https://www.inaturalist.org/taxa/369647-Sporobolus-pyramidalis

*Sporobolus sp.

*+Urochloa brizantha
https://www.inaturalist.org/taxa/279501-Urochloa-brizantha
eaten intensively in November and March

*unidentified grass, possibly Pennisetum sp.
eaten intensively in November

HERBACEOUS DICOTYLEDONOUS PLANTS

Acanthaceae:

*Justicia sp.
https://www.inaturalist.org/observations?place_id=12329&subview=map&taxon_id=50152&view=species

Faboideae:

*Crotalaria emarginata
https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:488087-1

*Galactia argentifolia
https://en.wikipedia.org/wiki/Galactia

WOODY PLANTS

Connaraceae:

*Rourea coccinea ssp. boiviniana
https://www.inaturalist.org/taxa/505872-Rourea-coccinea

Mimosoideae:

+Albizia adianthifolia
https://www.inaturalist.org/taxa/128969-Albizia-adianthifolia

+Albizia gummifera
https://www.inaturalist.org/taxa/132903-Albizia-gummifera

Polygalaceae:

*+Securidaca longipedunculata
https://www.inaturalist.org/taxa/593974-Securidaca-longepedunculata

Santalaceae:

+Ximenia caffra
https://www.inaturalist.org/taxa/340166-Ximenia-caffra

The following excerpts from the text in Estes and Estes (1969) are relevant to diet.

EXCERPTS

Pages 9-10:

"The sable is primarily a grazer on grasses of medium height, preferring the greenest and tenderest available plants. The Longo Magandi herd often specialised on one or two common grasses for a few days while the plants were at the preferred stage of growth, changing to others when the first ones became a little taller and coarser. Plants were usually not grazed shorter than about four inches. Two areas that were burnt in November and December were unutilised by sable until the leaf table exceeded six inches, although tall unburnt grassland was the only alternative. However, the unburnt grassland offered an understorey of green grass. The usual grazing method is to gather in a clump of blades with dexterous lip movements, then to bite off and chew a length of up to a foot...Generally speaking, the sable grazed most intensively around the edges of the copses, in hollows and on termite mounds in open grassland - i.e. in the places where the lushest, tenderest grasses grow...[several] of the grasses, which grow most abundantly in these situations but are not among the commonest grasses, were heavily grazed by sable so long as they were green and young: Megathyrsus maximus, Digitaria milanjiana, and Urochloa brizantha. An unusual habit of Shimba Hills sable is bone-chewing. It was observed on 30 different occasions, and appeared to be a practice indulged in by all herd members. It was usual for an animal to spend up to half an hour chewing a bone, meanwhile frothing at the mouth, and even to transport small pieces from one place to another when the herd moved. The sites of an elephant and of a buffalo skeleton were among the places most frequently visited by the Longo Magandi herd. At those places animals were seen apparently seeking pieces of bone to chew. Long bones were evidently preferred, but probably because few remained at these sites, sable were also seen to chew pieces of pelvis and even vertebrae. Glover also comments upon bone-chewing behaviour. The pronounced deficiency of calcium and phosphorus in Shimba Hills soils is a probable explanation. Yet the sable and other wildlife had failed to discover salt and bone meal put out on a cleared piece of ground the previous November by the following March. Although it was sited near a route not infrequently used by the sable, apparently it remained undetected. The obvious solution would be to establish a lick at one of their 'bone yards'."

Page 6:

"The grassland consists mainly of tufted perennials, separated by bare ground; basal cover averages probably less than 5 percent. While there are many species, tall stalks of Hyparrhenia filipendula and Hyperthelia dissoluta appear dominant following the long rains unless burnt off during the dry season. Andropogon spp., especially A. dummeri and A. schirensis, are co-dominant and may actually be more plentiful though less conspicuous. In Makin's (p. 14) view, Andropogon is an 'unpalatable and poorly nutritious grass which characterises burnt-over and infertile soils.' This genus is nevertheless heavily utilised by sable in most of the areas we have investigated. A far more unpalatable grass, which grows in widely separated clumps and dominates on gravelly slopes, is Trachypogon spicatus [https://www.inaturalist.org/taxa/169858-Trachypogon-spicatus]; neither it nor Cymbopogon caesius https://www.inaturalist.org/taxa/461690-Cymbopogon-caesius was ever seen to have been grazed."

For the crucial role of mineral nutrients in the diet and drinking water of the sable antelope, please also see https://www.jstor.org/stable/3830391.

to be continued in https://www.inaturalist.org/journal/milewski/87182-diet-of-the-sable-antelope-part-2-hippotragus-niger-niger#...

Posted on November 25, 2023 04:50 PM by milewski